My equipment has a LEMO multi-pin receptacle and I need the mating plug. How do I determine the LEMO part number I need?


Before LEMO can assist with a mating plug part number, we must first identify the LEMO receptacle.

First, check your equipment documentation to see if the LEMO part number is included.
If not, check the equipment manufacturer's web site to determine if they reference this information.
If the first two steps do not yield a LEMO part number download a Receptacle Identification Guide for more assistance.

Are LEMO connector design trademark registered?

Yes. LEMO's distinctive "chocolate plate" connector design is a registered trademark US Reg 2'703'464 and Europe Registration 798'106

The mark consists "...of truncated pyramidal projections formed on an outer surface of a connector, and with each truncated pyramidal projection having a square based on a square top"

Can I distinguish a full part number from partial data on my LEMO plug or receptacle?

The 5th letter of a LEMO part number is an indication of the connector series. Other information needed to determine a full part number is as follows: How many contacts (pins) are in the insert of the connector? Is the shell soft chrome plated brass shell? Are the terminations solder or crimp? What is the diameter of the cable entering the rear of the connector (in millimetres if possible)? Is there a bend relief (strain relief) at the transition between the connector and the cable? What is the colour of the connector?

See Part Numbers Explained for more information about LEMO's part numbering system.

How does LEMO determine the maximum recommended operating voltage?
LEMO takes pride in strictly following the IEC Standard.
LEMO always has the safety of the user in mind when LEMO publishes specs or make recommendations. 

LEMO determines its published Operating Voltage V(signal) specifications as follows:

Per IEC 60512-2 Test 4a Standard:

 V(test) = 0.75 x V(breakdown) 
 V(signal) < 1/3 x V(test)
V(breakdown) = Mean breakdown voltage 
V(test) = Test Voltage 
Substituting V(test) in equation (2) through V(test) 
from equation (1) yields equation (3): 
 V(signal) = 1/3 x 0.75 x V(breakdown) = 1/4V(breakdown)


Can I download PDF drawings of LEMO connector from this web site?
No, however, in the near future this feature will be added. In the meantime, you can contact LEMO engineering for CAD files.


My equipment has a LEMO receptacle with a concentric contact, how do I determine the part number?
The Concentric Contact Guide should enable you to re-create the LEMO part number for most concentric connectors.
You can also refer to Part Numbers Explained for more information.
You may need to contact LEMO for identification assistance with the following different types of concentric electrical contact connectors:
•Coax contact
•Triax contact
•Unipole contact
•High Voltage contact
When contacting LEMO please mention that you estimated or re-created this part number so that Customer Service can double-check the information.
Does LEMO have BNC adaptors?
Yes, you can find several BNC adapters referenced in the NIM-CAMAC 00 series Catalog.


What is a cable group?
LEMO's coaxial contacts are designed to accept a range of coaxial cables.
A LEMO cable group describes the group of cables that are compatible with a particular contact.
For example, the 2B.802 can work with cable group 1 (RG.174 A/U, RG.188 A/U, RG.316 /U), group 2 (RG.178 B/U, RG.196 A/U) and group 3 (RG.179 B/U, RG.187 A/U).
For more information, contact


What type of thread lock material may I use on REDEL® connectors?
LEMO recommends cleaning the connector with Isopropyl Alcohol prior to thread lock adhesive.
We have a specific formulation of Vibra-Tite® for the PSU (Polysulfone) and PEI (Polyetherimide) used by LEMO, VTCS-6. For more detail, view the assembly instructions.


How do I know if I have a LEMO Connector?

A LEMO plug is typically marked with the LEMO name and the first 5 characters of the part number, which represent the model, size, and series.For more information, download a detailed Plug Identification Guide A LEMO receptacle is typically marked with the LEMO name and the first 5 characters of the part number, which represent the model, size, and series.For more information, download a detailed Receptacle Identification Guide

Does LEMO offer customer specific stocking programs?
LEMO entities in the U.S.A., Germany, United Kingdom, and in other countries hold large inventories in order to meet expected demand of products or parts.
This helps to ensure that standard parts are available within a short lead-time. For customers with significant large-volume business, LEMO offers discounts and safety stocks.
A safety stock is an amount of inventory reserved for a customer according to an existing contract.
Please contact LEMO to discuss forecasts, delivery, and safety stock needs, and to negotiate an individual agreement.


How do I order my plug with a bend relief?
Bend reliefs are ordered separately from plugs.
They come in various colours, and with different inside diameters.
When ordering a plug, add the variant letter "Z" to the end of the part number to specify a rear collet nut with a lip to accept the bend relief.
See Part Numbers Explained for more information about LEMO's part numbering system.


I have a wireless microphone module and the connector on it appears to be a LEMO connector. How do I determine the LEMO part number to order these connectors?
 Please download LEMO's Audio Connectors for Microphone Applications Datasheet


What is the meaning of the letters Y or W at the end of a part number?
The letters "Y" and in some cases "W" have been used for special designs.
In general they indicate that a catalog item has been modified in order to meet a specific need in a particular application.
Common specials can be looked-up using the Search By Part Number.
Otherwise, contact to get details about what is unique in your specific part number.


What is the meaning of the letter "Z" at the end of a part number?
A "Z" at the end of a part number usually indicates that something is missing. For example, if you add a "Z" to the part number of a free plug (FGG, FFA) then the plug will be equipped with a nut for fitting a bend relief. The bend relief itself must then be ordered separately. A "Z" at the end of a part number for a panel-mount receptacle (EGG, ERA) often removes the washer and nut from the product so that you can use your own hardware.


How does the AC Current specifications relate to the DC Current specifications?
In general heat generation and dissipation limits the maximum current for a contact.
Because an AC (rms) current of the same amount as a DC current causes the same power loss for a given contact resistance, the maximum current specification is the value for DC and AC (rms).


How does the AC Voltage specifications relate to the DC voltage specifications?
In general the AC voltage assumes a 50-60 Hz sinusoidal waveform and is the RMS (root mean squared) value.
The DC Voltage ratings are the AC voltage values times 1.41 (usually rounded).


What is an NEMA rating, and how do I cross-reference with an IP rating?
Two widely accepted rating systems are the NEMA and the IP codes. NEMA, short for National Electric Manufacturers' Association, is commonly specified at installations in the U.S.A. IP, which is an abbreviation for International Protection, is derived from the IEC.
IP and IEC are more common in Europe and Asia.
NEMA Definitions

Here are the NEMA 250 classifications:

1 Intended for use primarily to provide a degree of protection against limited amounts of falling dirt.
3 Outdoor protection against rain, sleet, windblown dust, and damage from external ice formation.
3R Outdoor, protection against rain, sleet, and damage from external ice formation.
3S Outdoor, protection against rain, sleet, windblown dust, and to provide for operation of external mechanisms when ice laden.
4 Indoor/Outdoor, protection against windblown dust and rain, splashing water, hose-directed water & damage from external ice formation.
4X Indoor/Outdoor, protection against corrosion, windblown dust and rain, splashing water, hose-directed water & damage from external ice formation.
6 Indoor/Outdoor, protection against hose-directed water, the entry of water during occasional temporary submersion at a limited depth & damage from external ice formation.
6P Indoor/Outdoor, protection against hose-directed water, the entry of water during prolonged submersion at a limited depth & damage from external ice formation.
12 Indoor, protection against circulating dust, falling dirt and dripping non-corrosive liquids.
12K Type 12 with knockouts

A Brief Comparison of NEMA 250 and IEC 60529

NEMA Enclosure IEC Enclosure
1 IP10
3 IP54
3R IP14
3S IP54
4 & 4X IP56
6 & 6P IP67
12 & 12K IP52


What is an IP rating?
IP stands for Ingress Protection.

International Electrotechnical Commission - IEC 60529 "Degrees of protection provided by enclosures (IP Code).". NEMA offers a similar rating system.

Definition of degree of protection (IP code)
IEC 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion of foreign bodies (e.g., tools, dust, fingers, and moisture) into the equipment. This classification system utilizes the letters IP (Ingress Protection) followed by two digits.


Degree of protection - First digit
The first digit of the IP code indicates the degree that the connector is protected against contact with moving parts, as well as the degree to which equipment is protected against solid foreign bodies intruding into an enclosure:
0 No special protection. 
1 Protection from a large part of the body such as hand or from solid objects greater than 50 mm in diameter. 
2 Protection against objects not greater than 80 mm in length and 12 mm in diameter. 
3 Protection from entry by tools, wires, etc., with a diameter or thickness greater than 2.5 mm. 
4 Protection from entry by solid objects with a diameter or thickness greater than 1.0 mm. 
5 Protection from the amount of dust that would interfere with the operation of the equipment. 
6 Dust-tight.

Degree of protection - Second digit
The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g., dripping, spraying, submersion, etc.).
0 No special protection. 
1 Protection from vertically dripping water. 
2 Protection from dripping water when tilted up to 15°. 
3 Protection from sprayed water. 
4 Protection from splashed water. 
5 Protection from water projected from a nozzle. 
6 Protection against heavy seas, or powerful jets of water. 
7 Protection against temporary immersion. 
8 Protection against complete continuous submersion in water (up to 1 meter deep for 15 minutes).

What is LEMO's position in regards to the requirements of RoHS (Restriction of Hazardous Substances) legislation?
LEMO Connectors and Accessories
LEMO certifies that its connectors and accessories marketed, manufactured, and shipped after January 1, 2006 are in full compliance with the requirements of Directive 2002/95/EC of the European Parliament and of the Council dated 27th January 2003 regarding the presence of: mercury, cadmium, lead, hexavalent chromium, polybromide biphenyl (PBB) or polybromide diphenyl ether (PBDE), including DecaBDE.
The Directive (EU Directive 2002/95/EC) specifies restriction of the use of certain hazardous substances in electrical and electronic equipment by July 1, 2006 and is known as the RoHS Directive
All part numbers will remain unchanged. The vast majority of all LEMO products require no adjustment for RoHS compliance. The few items that have internal solder connections have moved to lead-free solder. There are a few connectors with an optional aluminum-alloy shell that contains lead in that alloy. For that shell option LEMO will switch to a RoHS compliant aluminum alloy by January 1, 2006.
Contacts Designed for Solder Connection
All LEMO connectors with solder-style contacts are fully compatible with lead-free solder and the required higher temperatures. LEMO insulators are made of high temperature material and the standard connecting surfaces are made of an Au/Ni plating. In addition, LEMO has conducted verification testing of contacts and cable assemblies with lead-free solder.
Cable and Product Assemblies by LEMO 
Standard cable and product assemblies from LEMO use lead-free solder. Cable assemblies and other value added products that require RoHS declarations of compliance will be available by June 1, 2006. Call us if you need help with certification earlier. LEMO also continues to offer custom services to meet customer specific requirements for both material and process (such as with solder selection) in cable and other product assemblies. Lead based or lead-free soldering processes are available.


Does LEMO have MIL-SPEC connectors?
All LEMO connectors are tested to MIL standard test requirements (see table below).
LEMO's F Series connectors meet or exceed performance requirements of military standards but are not "MIL-SPEC" connectors.
Examples of LEMO's B and F series testing include:
Tests MIL Method
Electrical Tests
Test Voltage rms 1344A 3001.1
Rated Voltage rms 1344A 3001.1
Contact Resistance 202 307
Shell Electrical Continuity 1344A 3007
Insulation Resistance 1344A 3003.1
VSWR f (Ghz) 1344A 3005
Mating Force 1344A 2013.1
Unmating Force 1344A 2013.1
Latching Force 1344A 2010.1
Straight Pull force on Cable 1344A 2009.1
Insertion Force on Contacts 1344A 2014
Retention Force on Contacts 1344A 2007.1
Lifetime 1344A 2016
Vibration 202 204C
Environmental Tests
Vacuum Test (if applicable) 1344A 1008
Hydrostatic Pressure Resistance (if applicable) 1344A 1006.1
Humidity Dependence of Working Voltage 1344A 1002.1


Are any of the LEMO connectors built to a specific connector standard?
Yes, two product series are built to standards, the LEMO NIM-CAMAC 00 Series, and the LEMO 3K.93C HDTV Camera Connector (see for the standards).
NIM modules (Nuclear Instrumentation Methods) are used to collect scientific data in nuclear particle research.
The NIM-CAMAC 00 Series front panel connectors are defined in this standard, NBS-549. View the NIM-CAMAC 00 Series.
LEMO HTDV Camera Connector – 3K.93C Series
The 3K.93C Series is used in the High Definition Television (HDTV) industry.
The standard is the ANSI/SMPTE 304M-1998 "Television - Broadcast Cameras - Hybrid Electrical and Fiber optic Connector."
The associated UL safety standard is UL1419 "Professional Video and Audio Equipment."
Does LEMO have ISO certification?
LEMO worldwide is ISO 9001 certified.
 Download the certificate


Do LEMO connectors have UL / CSA recognition?

Yes, many LEMO connectors have Underwriters Laboratories (UL) recognition and UL for Canada recognition.

For further details go directly to the UL web site and search by the file number:E119802.


The web site displays product details different than the LEMO catalog. Which one is right?
Despite extra care, changes or typographical and other errors may occur after the catalog is printed.
Please report a discrepancy by contacting
LEMO will correct the information in the catalogs, and update the web site.
Also, please be advised that specifications, drawings, and other technical information are subject to change at any time and without notice.
If you depend on particular features, properties, or performance characteristics, then please contact LEMO to discuss your individual needs.


What do the following terms mean in the connector SEARCH?
Low voltage contact
A low voltage contact has no additional protection, such as an insulating sleeve, and is intended to run low voltages.
However, depending on the distance to other contacts and the shell, its breakdown voltage under laboratory conditions can still be hundreds, or even a few thousand volts.
LEMO recommends applying only operating voltages low enough to be considered safe in the target application.

 Download the Concentric Contact Identification Guide for illustrative comparisons.


High voltage contact
A high voltage contact has an additional insulating sleeve that provides longer creepage distances.
It allows high voltages over a wide range of temperatures, humidity, and altitudes. In general, its breakdown voltage tends to be higher compared to low voltage contacts.
The additional insulator can also reduce the risk of touching a dangerous voltage (LEMO recommends to always turn off power before disconnecting any type of connector).

 Download the Concentric Contact Identification Guide for illustrative comparisons.


Coaxial contact
A coaxial contact is a concentric mechanical design to achieve a given electrical impedance.
Electrical impedance is the ratio of the electrical field and the magnetic field of a wave traveling in a cable or through a connector and should not be confused with the contact resistance (typically a very small fraction of one ohm).
Typical electrical impedances are 75 ohm for audio and video signals (analog radio and television) and 50 ohm for most other applications.

 Download the Concentric Contact Identification Guide for illustrative comparisons.


Triax contact
A triaxial contact is a coaxial contact with an additional shielding.
Triaxial cables and contacts provide better electromagnetic compatibility (EMC) and cause less radio-frequency interference (RFI).
Because they are most common in the broadcast industry, they usually have 75 ohm impedance.

Quadrax contact
A quadrax connector design has a center contact plus three concentric contacts, allowing connection of four wires.
Because you can rotate the connector in any direction it provides convenience. Quadrax designs often are used for audio (stereo) applications.

Thermocouple contact
A thermocouple is an electric temperature sensor consisting of two different metals.
In order to reduce measurement errors due to temperature differences in a connector, it is important that connector contact materials match the metals used to make the temperature sensor.
LEMO's thermocouple connectors have pairs of thermocouple contacts (enter number of contacts = 2, 4, 6, etc. in "Thermocouple" on the Advanced Search page).
To specify a thermocouple connector with a grounding contact, enter 2 in "Thermocouple" and 1 in "Low Voltage".

Fluidic/pneumatic contact
Fluidic contacts for medical, dental and industrial applications allow you to connect single or multiple tubes and hybrid electrical/fluidic cables. They can also be used for air.

Fiber Optic
LEMO offers a variety of ceramic and metal ferrules that can accept different fibers.
These ferrules are grouped into four categories.
Each category has been designed for a certain number of contacts (type F1/F2: multiple fiber optic or electrical/optical hybrids, type F3/F4: connectors with just one fiber optic contact) and ferrule hole sizes (type F2/F4: 125 to 140 um, type F1/F3: 140 to 1650 um).

Shell Style
Shell Style is a way of grouping connectors into categories. The most common shell styles are free (straight or elbow) plugs and fixed (front/rear mount) receptacles.
"Front mount" indicates that the connector normally is mounted from the outside (front side) of a panel. "Rear mount" indicates that the connector normally is mounted from the inside (rear side) of a panel. Printed circuit board connectors in general belong to the "rear mount" style because most of them are soldered in place before the board gets mounted inside a chassis.

Insert Style
Insert Style groups various contact configurations, such as single contact, multiple contact, coaxial, fiber optic, hybrid, etc.

Termination Style
Termination Style describes how you connect your cable or printed circuit board to the connector.
Solder: soldered to a stranded or solid wire.
Crimp: used for stranded wires.
Printed Circuit Board: has straight leads.
Elbow-PCB: has 90 degree elbow leads to a through-hole printed circuit board.
Fiber optic terminates, optical fiber, and Fluidic/Pneumatic: intended for tubes.
Thermocouple: special solder contacts for sensors based on the thermoelectric effect.

Explanation of frequently-used acronyms seen in searching connectors:
Low Voltage contact(s)
High Voltage contact(s)
Coaxial contact(s)
Triaxial contact(s)
Quadraxial contact(s)
Fiber optic contact(s)
Thermocouple contact(s)
Fluidic/pneumatic contact(s)
Coaxial or triaxial impedance (50 or 75 Ohm)
Diameter in mm (unless specified otherwise)
Printed Circuit Board
Elbow (90 degree) design for printed circuit board


SEARCH did not find a connector based on my entry. How should I modify my entry to increase the likelihood?
It depends on which search you use. Here are some of the more common scenarios:
Part Number Search:
Common typographical errors include: 
Using the digit "5" instead of the letter "S" and vice-versa 
Using the letter "I" instead of the digit "1" 
Using the letter "7" instead of the letter "Z" and vice-versa 
If you cannot resolve this issue, please contact us at for further assistance.
Advanced (or occasionally basic) Search: 
Check your color requirement. Your connector of choice might be in the database in other colors (contact LEMO to get your color). 
Clear the Cable Ø fields and repeat the search. 
Do not specify a connector diameter or length unless it is absolutely critical. 
Try the S Series instead of B and vice versa (same for E and K). 
Choose a different Shell Style. 
Try both solder and crimp termination, or printed circuit board (PCB). 
You can also use the Connector Design Connector Quote Form for further assistance from LEMO (typically takes one business day).
Product Details Page:
Change the sequence if you want to modify more than one parameter, or go to the advanced search page and start over.
The "modify" choices at the end of the product details page include only "adjacent" values (i.e., the search engine looks for parts like the current one, except that they differ in the one aspect you are trying to modify.
For example, if you are looking at an F Series connector, then you will see different numbers of low-voltage contact configurations.
However, you will not see all the insert styles that LEMO offers in other series.


How does the advanced SEARCH apply Volts and Amps to hybrid connectors or those with different pin sizes?
In general, the search engine makes sure that at least one contact meets or exceeds required "Volts" entry, and at least one meets or exceeds the "Amps" criterion.

For example, the 2B.708 insert has one high voltage contact (8,000 Volts, 4 Amps) and eight low voltage contacts (750-1,500 Volts, 10 Amps).

The software will compare your voltage criterion with the best-case voltage specification (in this case, high voltage contact) and the best-case current specification (in this case, low voltage contact).
In some hybrids, the same contact exceeds both criteria; in some others, like the example above, two different contacts qualify. For more information, please refer to the pdf catalog document.


What does Readily Available Parts mean on the LEMO web site?
Non-standard parts have unique features to meet specific applications, and typically take 6-12 weeks to deliver.
Because it takes only one non-standard component to make a product no longer readily available, the less specific you are in the advanced search, the wider the range of search results.
The search engine tends to default to readily available parts whenever possible.


Which of the LEMO F Series panel mount receptacle have seals and which do not?
The EH_, HE_ and ED_ have a front panel seal. The EG_, EC_, EE_, PE_ and PB_ do not.


How can I achieve an IP68 Rating with LEMO's K&E Environmentally sealed connectors?
LEMO publishes a rating of IP66/68 for LEMO K&E Series connectors.
There are 3 sealing points on a typical mated pair.
  1. Seal between the plug and receptacle
  2. Seal between the receptacle and the panel
  3. Seal between the plug and the cable

IP68 is achieved for points 1 and 2. The connector to cable seal is highly dependant on the shape of the cable, therefore it can range from IP66 to IP68.

 For complete details, please see LEMOs IP66-68 Rating Reference Guide for K&E Series Connectors.


In LEMO fiber optic connectors, what is a "T-adapter"?
The "T-adapter" is a component supplied with the LEMO K series fiber optic connectors that facilitates the secure attachment of the cable jacket to the rear of the connector, and permits an epoxy type moisture seal, preventing moisture ingress in to the cable from that junction.
For further details see "Cable Fixing" in the Technical Library.


What does the letter Z signify as a contact code in LEMO fiber optic connectors?
A "Z" usualy designates no electric contacts. If the connector configuration calls for only fiber optic contacts, the letter "Z" must be entered in the contact code location to ensure proper encoding of the part number.

Example: the FGG.3K.03A.CLZC65 is a straight plug with a cable collet and two holes for fiberoptic contacts . Note that you must order the two fiber optic contacts separately.


What is the significance of the "W" keyway code in the 3K.93C HDTV fiber optic connector part numbers?
In order to ensure safety to the system and users, the "W" five-key system is assigned exclusively to the HDTV broadcast camera connectors (see ANSI/SMPTE 304M-1998/311M-1998, ARIB BTA S-1005B or EBU R100-1999).
In other cases select a different key code (for example, "G" or "A" or "J").


I plan to terminate LEMO fiber optic connectors at my site. What are the tools I would need to complete the task?
The type of connector chosen (single or multi-fiber, hybrid, sealed or not sealed), determines the tools required to terminate LEMO fiber optic connectors.
For your convenience, LEMO has gathered the most common tools and accessories for 125 mm fiber connector assembly into a single kit, complete with a carrying case. 

For advice on terminating the various types of LEMO fibre optic connectors please contact your local LEMO supplier.

Instructions include the following guide lines


  • 900um Buffered Fibre 
  • Tight Jacket Cable 
  • Multiway Optical Cable 
  • Multiway Hybrid Cable 
  • Hand Polishing Instructions 
  • Machine Polishing Instructions 



Does LEMO have remote handling or telemanipulator connectors for low power manipulators?
Yes, the "Y" type units on the LEMO N Series have a lever to assist with mating and unmating.


Does LEMO have gamma radiation tolerant (rad-hardened) connectors?
Yes, LEMO has several connector series that have optional Stainless Steel shells, PEEK inserts, and for wet environments the sealed versions have optional EPDM seals.
(Note: EDPM seals are standard on the N Series).


Does LEMO have connectors to facilitate robotic connections using robot telemanipulator action?
Yes. The LEMO N Series Connector was designed specifically for robotics use in telemanipulator applications.
In addition, LEMO has several models in LEMO B Series, S Series, K Series, and E Series connectors, which are also suitable.


Glossary A - E



Alloy: A combination of two or more metal elements.
Alternating Current (A-C): Current in which the charge-flow periodically and regularly reverses in a cyclic manner.
American Society for Testing Materials (ASTM): An organization that tests materials and attempts to set standards on various materials for industry.
Ampere (A): The unit expressing the rate of flow of an electrical current. One ampere is the current flowing through one ohm of resistance at one volt potential.
Annealing: The process of heating to and holding at a suitable temperature and then cooling at a suitable rate, for such purposes as reducing hardness, improving machinability, facilitating cold working, producing a desired micro-structure or obtaining desired physical, mechanical or other properties.
Anodizing: An electrolytic process for producing a protective or decorative film on certain metals chiefly aluminum and magnesium.
ARIB: An acronym for Association of Radio Industry Broadcasters, a standards organization in Japan.
AWG: Abbreviation for American Wire Gauge, a measure of the size or diameter of a wire or conductor.
Back Reflection (Fiber Optic): A measure of the percentage of power reflected back by a discontinuity in a fiber optic line. It is expressed in dB.
Bandwidth: The frequency range over which the connector or device can operate without degradation of performance. Also the information carrying capacity of digital systems.
Base Metal: The metal from which the connector, contact or other metal accessory is made and on which one or more metals or coatings may be deposited.
Bend Radius: The maximum amount fiber or cable that can be bent without causing damage. Also called minimum safe bending radius.
Braid: The covering formed from textile yarn. Braids provide mechanical and thermal protection to plastic insulation, separate cable segments in multi-conductor cables and act as components in flame retardant cables. See also Shield.
Breakdown Voltage: The voltage at which the insulation between two conductors will break down.
Bundle (Fiber Optic): A number of fibers grouped together (rigid or flexible), usually carrying a common signal (or an image, or a conduit for transfer of light power).
Cable: An insulated conductor or group of individually insulated conductors in twisted or parallel configurations.
Cable Assembly: A completed cable and its associated hardware.
Center Conductor: The inner conductive member in a coaxial structure, such as center contacts.
Cladding (Fiber Optic): A layer of glass (or other material) surrounding the core of a fiber, forming the conduit that carries the light through the fiber. It has a refractive index slightly lower than the core.
Coaxial Line: A transmission line consisting of a center conductor suspended in a hollow cylindrical tube with or without a dielectric support. The hollow cylindrical tube is called the outer conductor.
Concentric: A central core surrounded by one or more layers of materials, all sharing a common central axis.
Conductor: A wire or combination of wires not insulated from one another, suitable for carrying electric current.
Connector: Used generally to describe all devices used to provide rapid connect/disconnect service for wires, cables, and fibers.
Contact Engaging & Separating Force: The force needed to either engage or separate pin and socket contacts when they are in and out of connector inserts.
Contact Inspection Hole: A hole in the cylindrical rear portion of contact used to check the depth to which a wire has been inserted.
Contact Plating: Plated-on metal coating applied to the basic contact metal to provide the required contact resistance and/or wear resistance.
Contact Resistance: The maximum permitted electrical resistance of pin and socket contacts when assembled in a connector under typical service use.
Contact Retention: Defines minimum axial load in either direction that a captive contact must withstand while remaining firmly fixed in its normal position within an insert.
Continuity Check: A test performed on a length of finished wire or cable to determine if the electrical current flows continuously throughout the length. Conductors may also be checked against each other to ascertain that there are no shorts between adjacent members.
Contacts: The conducting members of a connecting device that are designed to provide a separable through connection in a cable-to-cable, cable-to-box or a box-to-box situation.
Core: (1) In cables, a term used to express a component or assembly of components over which other materials are applied, such as additional components, shield, sheath, or armor; (2) In fiber optics, the transparent glass or plastic section with a high refractive index through which the light travels by internal reflections.
Corrosion: Corrosion is the slow destruction of materials by chemical agents and electrochemical reactions. The most common kind of corrosion is that of rusting.
Coupler: An intermediate device to provide for attaching special accessories or to provide special mounting means. the method for connecting two connectors that cannot intermate.
Creepage Path: The path electricity must travel across the surface of a dielectric between two conductors. Lengthening the creepage path reduces the possibility of arc damage or tracking.
Crimp Termination: A connection in which a metal sleeve is secured to a conductor by mechanically crimping the sleeve with pliers, presses or automated crimping machines. Splices, terminals and multi-contact connectors are typical terminating devices attached by crimping. Suitable for all wire types.
Current (I): The rate of transfer of electricity, usually expressed in amperes.
Current Rating: The maximum continuous electrical flow of current recommended for a given wire in a given situation. Expressed in amperes (AMPS).
Cycle: The complete sequence including reversal of the flow of an alternating electric current.
dB: (1) Abbreviation for decibel; (2) The loss of a signal in a conductor expressed in decibels, denoting the ratio of the power input to output; (3) One tenth of a bel.
Delay Line: A cable made to provide a very low velocity of propagation with a long electrical delay for transmitted signals.
Derating Factor: A factor used to reduce a current-carrying capacity of a wire when used in environments other than that for which the value was established.
Dielectric: (1) Any insulating medium that intervenes between two conductors and permits electrostatic attraction and repulsion to take place across it; (2) A non-conductive insulator. An "insert" material.
Dielectric Constant (K): That property of a dielectric that determines the electrostatic energy stored per unit volume for unit potential gradient. Also called permittivity and specific inductive capacity.
Dielectric Strength: The voltage which an insulating material can withstand before breakdown occurs, usually expressed as a voltage gradient (such as volts per mil).
Direct Current (D-C): An electric current that flows in only one direction, substantially constant in value.
Durometer: A measurement used to denote the hardness of a substance, usually an elastomer.
Eccentricity: A measure of the center of a conductor's location with respect to the circular cross-section of the insulation surrounding it, expressed as a percentage of center displacement of one circle within the other.
Elastomer: A material which at room temperature, stretches under low stress to at least twice its length and snaps back to original length upon release of stress. Example: rubber.
Electroplating: The electrode position of an adherent metal coating on a conductive object for protection, decoration, or other purposes.
Engaging and Separating Force: The amount of force needed to engage and/or separate contact elements in mating connectors. See "Contact Pressure."
Environmentally Sealed: A connector provided with gaskets, seals, potting, or other devices to keep out moisture, dirt, air, or dust which might lower its performance.
Epoxy Resin: Plastic materials that become hard, infusible solids upon the addition of a hardening agent. Epoxy resins have excellent adhesive action, high chemical, solvent, and thermal resistance, and low shrinkage on curing.
Extraction Tool: A small, hand-held tool used to extract contacts from a connector.
Glossary F - K


Feed-Thru: A connector or terminal block usually having double-ended terminals which permit simple distribution and bussing of electrical circuits. Also used to describe a bushing in a wall or bulkhead separating compartments at different pressure levels with terminations on both sides.

Ferrule: A short tube used to make solder-less connections to shielded or coaxial cable. In fiber optics, a tube with a central hole that holds the fiber in a connector.

Fiber (fiber Optic): A short tube used to make solder-less connections to shielded or coaxial cable. In fiber optics, a tube with a central hole that holds the fiber in a connector.

Fiber Optics (F.O.): A general term describing a lightwave or optical communications system. In such a system, electrical information is converted to light energy, transmitted to another location through optical fibers and is there converted back into electrical information.

Flange: A mechanical shoulder on the outside housing, enabling attachment to a panel; can also allow for seals with gaskets or o-rings.

Flexible: That quality of a cable or cable component which allows for bending under the influence of outside force, as opposed to limpness, which is bending that occurs due to the cable's own weight.

Fluorinated Ethylene Propylene (FEP): FEP is similar to polytetrafluoroethylene (PTPE) but has a melting point of about 50° C lower and slightly different physical properties.

Frequency: The number of times an alternating current repeats its cycle in one second, expressed in cycles per second, or Hertz (Hz).

Front Mounted: A connector is front mounted when it is attached to the outside or mating side of a panel. A front mounted connector can only be installed or removed from the outside of the equipment.



Gasket: A component made from an elastomer, such as rubber, to provide an environmental seal in the interface of a connector pair. Also called a "grommet".

Giga: A numerical prefix denoting one billion (109)

Graded Index Fiber (Fiber Optic): A multimode fiber whose core refractive index increases in controlled fashion outward from the axis and matches the cladding refractive index at the core-clad interface. Has greater bandwidth than step index fiber, but less bandwidth than single mode fiber.

Ground (GRD): An electrical term meaning to connect to the earth or other large conducting body to serve as an earth, thus making a complete electrical circuit. Sometimes at zero potential or voltage.



Hard Clad Silica (Fiber Optic): Abbreviated HCS, it is a structure in fibers where the cladding around the glass core is a hard plastic, as opposed to a "PCS," which is a soft plastic cladding.

Heat Shrinkable: The term describing tubes, sleeves, caps, boots, films, or other forms of plastic which shrink to encapsulate, protect or insulate connections, splices, terminations, and other configurations.

Hermetic: Permanently sealed by fusion, soldering, or other means to prevent the transmission of air, moisture vapor, and all other gases. Hermeticity is usually expressed as the rate of leakage volume of tracer gas (such as helium) per second in time.

Hertz (Hz): Unit of frequency equal to one cycle per second.

High Definition Television: Abbreviated as HDTV, a recent form of broadcast of television signals in a significantly higher resolution providing images of superior quality. HDTV signals in the studios and arenas are normally carried over optical fibers due to the high bandwidths required for the digitized signal data.

Hi-pot: A test designed to determine the highest potential that can be applied to a conductor without breaking through the insulation.

High Voltage: Generally, a wire or cable with an operating voltage of over 600 volts.

Holding Strength: The ability of a connector to remain assembled to a cable when under tension.

Housing: The main or largest portion of a connector to which other portions are attached or enclosed.



Impedance (Z): The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, expressed in ohms and designated by Z.

Infrared (Fiber Optic): Light with wavelengths 700-1000 nm, invisible to the eye, and felt as heat.

Inner Conductor: The central conductive member in a coaxial structure, such as the center contact in a coaxial connector.

Insert: That part which holds the contacts in their proper arrangements and electrically insulates them from each other and from the shell. Also called dielectric, insulator, or dielectric support.

Insert Retention: The axial load in either direction that an insert must withstand without being dislocated from its normal position in the connector shell.

Insertion Loss: The loss in load power resulting from the insertion of a cable, component, or device. It is expressed in decibels as the ratio of power received at the load before insertion to the power received at the load after insertion.

Insertion Tool: A small, hand-held tool used to insert contacts into a connector.

Insulation: A material which offers high electrical resistance, making it suitable for covering components, terminals, and wires. This prevents the possible future contact of adjacent conductors resulting in a short circuit.

Insulation Resistance: The ratio of the applied voltage to the total current between two electrodes in contact with a specific insulator.

Interface: (1) A shared boundary;(2) The two surfaces on the contact side of both halves of a multiple-contact connector that face each other when the connector is assembled; (3) In fiber optics, the surface where two materials meet, as in core-cladding interface, or fiber-to-fiber interface in a connector.

ISO: Abbreviation for International Organization for Standardization.



Jacket: An outer non-metallic protective covering applied over an insulated wire or cable.



Key: A short pin or other projection which slides in a mating slot or groove to guide two parts being assembled. Generally used in round, shell-enclosed connectors to prevent mating wrong connectors and to assist in polarization.

Keyway: The slot or groove in which a key slides.

Kilo: A numerical prefix denoting 1000 (10³)

Glossary L - Q

Laser (Fiber Optics): An acronym for "light amplification by stimulated emission of radiation," a device that generates intensified light, usually very directional and over a narrow range of wavelengths. Often a source of light in fiber optic systems.

Light (Fiber Optic): An electromagnetic radiation in the wavelength range including infrared, visible, ultraviolet, and X rays, usually the range visible to the human eye, i.e., the energy that enables vision. Light travels in a vacuum at 300,000 km/sec. (186,281 miles per second).

Lightguide (Fiber Optic): A fiber or a flexible bundle of fibers used to transmit light.

Loose Buffer (Fiber Optic): Also called "loose tube," a protective tube loosely surrounding a cabled fiber, often filled with a gel.

Loss: Energy dissipated without accomplishing useful work, attenuation, usually expressed in dB.

Lug: A mechanical termination, usually crimped or soldered to the conductor, with provision for threading on to a terminal; hardware.



Mate: To join two connector halves in a normal engaging mode.

Mega: A numerical prefix denoting one million (106).

Meter: Unit of length, equal to 39.37 inches.

Micro: A numerical prefix denoting one-millionth (10-6).

Micrometer: One millionth (10-6) of a meter, a unit of length. Used to specify wavelengths.

Micron: (Short for the preferred form "micrometer"): a measure of length equal to 10-6. Used to specify wavelength, it is equal to 1000 nanometers, the preferred term.

Mil: (0.001"): A unit used in measuring the diameter of wire or thickness of insulation over a conductor.

Milli: A numerical prefix denoting one thousandth (10-3).

Mode (Fiber Optic): One of the components of a general configuration of a propagating wave front. Mode is characterized by a particular geometrical pattern and propagation constant.

Moisture Resistance: The ability of a material to resist absorption of moisture.

Multimode Fiber (Fiber Optic): A fiber that transmits many modes.



Nano: A numerical prefix denoting one-billionth (10-9).

Near Infrared: The part of the infrared electromagnetic spectrum near visible wavelengths, in the range of 700 to 1500/2000 nm.



O-Ring: An elastomer gasket enabling a moisture seal, having a circular cross section. See Rubber.

Ohm: Unit of electrical resistance. Resistance of a circuit in which a potential difference of one volt produces a current of one ampere.

Outer Conductor: The external conductive member in a coaxial structure, such as the housing in a coaxial connector.

Overall Diameter: Finished diameter over wire or cable.

Oxidation: Oxidation can be considered the simple addition of oxygen to a metal, e.g., the addition of atmospheric oxygen to iron to form familiar rust. See Corrosion.



PTFE: Abbreviation for polytetrafluoroethylene, commonly known as Teflon.

Phosphor Bronze: This strong and relatively hard alloy is used to fabricate metal parts and springs. Phosphor bronze is resistant to corrosion.

Photon: A quantum of electromagnetic radiation, a unit of light. Light can be viewed as a series of photons.

Physical Contact (Fiber Optic): Abbreviated as PC, this is a design feature of fiber optic connectors, where the mating contacts' faces are in contact and under pressure provided by springs, resulting in lower loss.

Pico: A numerical prefix denoting one-millionth of one-millionth (10-12).

Pin Contact: A male-type contact, usually designed to mate with a socket or female contact. It is normally connected to the "dead" side of a circuit.

Pinholes: Small holes visible on the surface of soldered joints, which generally indicate the presence of a larger void within the joint. Typically caused by the generation of gas during solidification due to presence of salts and water. Sometimes called blowholes.

Plastic Clad Silica (Fiber Optic): A fiber structure where the cladding around the core is a soft plastic, abbreviated PCS.

Plastic Fiber: An optical fiber made of plastic alone.

Plating: The overlaying of a thin coating of noble metal on metallic components to improve conductivity, provide for easy soldering or prevent rusting or corrosion.

Plug: The part of the two mating halves of a connector that is free to move when not fastened to the other mating half. The plug is usually thought of as the male portion of the connector. The plug may have female contacts if it is the "free to move" member.

Polarization: The arrangement of mating connectors such that the connectors can be mated in only one orientation.

Polarizing Pin, Key, or Keyway: A device incorporated in a connector to accomplish polarization.

Polishing (Fiber Optic): The act of smoothing ends of fibers to an "optically smooth" finish, generally using abrasives. Optically smooth surfaces allow maximum transmission of light between fibers at connections, and minimize coupling loss.

Polyethylene: A thermoplastic with toughness, flexibility at low temperatures, resistance to chemicals and moisture, processability, and relatively low price.

Polytetrafluoroethylene (PTFE): This is the most thermally stable and chemically resistant of all carbonaceous insulating compounds. It is unaffected by sunlight, moisture, and practically all chemicals. Temperature range is -90° to 250° C and electrical properties are very constant over the temperature range and a wide range of frequencies.

Potting: The sealing of a cable termination or other part with a liquid composition that hardens into an elastomer or solid plastic material.

Pre-Tinned Solder Cup: Solder cups whose inner surfaces have been pre-coated a small amount of tin lead solder.

Press-fit Contact: An electrical contact that can be pressed into a hole in an insulator, printed board (with or without plated-through holes), or a metal plate.

Printed Circuit: This term is in common use with at least two meanings: 1) A generic term to describe a printed board produced by any of a number of techniques used to fabricate electrical interconnect systems. 2) A circuit obtained by printing and comprising printed components.



Quadrax: An abbreviation of quadraxial, a concentric cable having a center conductor, two intermediate conductors, and an outer shield, all separated by insulation.

Quick Disconnect: A type of connector shell that permits rapid locking and unlocking of two connector halves.

Glossary R - W

Radio Frequency (RF): The frequency range is technically broad, from about 25 kHz to 100 GHz, but the term is normally used to define the low range band of frequencies used for broadcast radio signals (including broadcast television) and extends from about 500 kHz to a few hundred megahertz.

Rear Mounted: A connector is rear mounted when it is insta1led from the inside of a box onto a panel. It can only be removed from the inside of the equipment. See Back Mounted.

Receptacle: Usually the fixed or stationary half of a two-piece multiple contact connector. Also the connector half usually mounted on a panel and containing socket contacts.

Reflection Loss (Fiber Optic): Energy reflected back toward a cable source. The reflections occur because the signal strikes a non-uniformity in the shield or conductor.

Resistance: A measure of the difficulty in moving electrical current through a medium when voltage is applied. It is expressed in ohms.

Return Loss: A measure of the percentage of the incident power that is reflected back down the transmission line. Return loss is the percentage reflected power expressed in dB notation.

RG/U: Abbreviation for Radio Guide, Universal. RG is the military designation for coaxial cable.

RMS or rms: Abbreviation for root-mean-square. When the term is applied to alternating voltage and current, it means the effective value; i.e., it produces the same heating effect as a direct current or voltage of the same magnitude. It is also a means of expressing a-c voltage in terms of d-c, usually approximately 70% of the a-c peak voltage.

Rubber: An elastic (natural or synthetic) material (e.g. silicone) used to provide waterproofing or moisture resistance. See O-ring.

Sheath: The outer covering or jacket of a multi-conductor cable.

Shield: In cables, a metallic layer placed around a conductor or group of conductors to prevent electrostatic or electromagnetic interference between the enclosed wire and external fields. See Braid.

Shield Effectiveness: The ability of a shield to screen out undesirable signals and prevent leakage.

SI: The standard international system of metric units of measurement.

Silica Glass (Fiber Optic): Glass made mostly from silica (silicon dioxide, SiO2) used to make fibers.

Simplex Cable (Fiber Optic): A single fiber cable.

Single Mode Fiber (Fiber Optic): Abbreviated as SMF, a fiber having a small core diameter (approximately 9 microns) with a cladding having a refractive index very close to that of the core. Will transmit light in a single mode that enters at a narrow angle but will transmit over very wide bandwidths.

SMPTE: An acronym for "Society of Motion Picture & Television Engineers," a USA standards organization.

Socket Contact: A female contact designed to mate with a male contact. It is normally connected to the "live" side of a circuit.

Solder: A metal or metal alloy, usually having a low melting point, used to join other metals having higher melting points than the solder.

Solder Cup: A tubular end of a terminal in which a conductor is inserted prior to being soldered. It is also the hollow cylinder at the rear of a solder contact where a wire is inserted and soldered in place.

Solid Conductor: A conductor consisting of a single wire.

Spring Finger Action: Design of a contact as used in a printed circuit connector or a socket contact, permitting easy, stress-free spring action to provide contact pressure and/or retention.

Step Index Fiber (Fiber Optic): A multimode fiber consisting of a core of uniform refractive index surrounded by cladding of a slightly lower refractive index. Accepts light rays over wider angle, but has smaller bandwidth than single mode fiber. See also Graded Index Fiber and Single Mode Fiber.

Stranded Conductor: A conductor composed of groups of wires twisted together.

Surface Mounting: The electrical connection of components to the surface of a conductive pattern without utilizing component holes in a circuit board.

Temperature Rating: The maximum temperature at which a material may be used in continuous operation without a loss of its basic properties.

Temper: (1)The hardness and strength produced by mechanical or thermal treatment or both. It is characterized by a certain structure, mechanical properties or reduction in area during cold working. (2)A measurement of the degree of hardness or lack of ductility in a metal.

Threaded Coupling: A means of coupling mating connectors by engaging threads in a coupling ring with threads on a receptacle shell.

Tight Buffer (Fiber Optic): A material surrounding a fiber in a cable, holding it firmly in place.

Tinning: Coating of a terminal, lead or conductive pattern with tin or solder alloy to improve or maintain solderability or to aid in the soldering operation.

Total Internal Reflection (Fiber Optic): The phenomenon of light rays reflecting at the core-clad boundary of an optical fiber, allowing transmission along the length of the fiber. It occurs when the angle of incidence is lower than the critical angle.

Transceiver: A device that combines both a transmitter and a receiver.

Transmission: The transfer of electric energy from one location to another through conductors or by radiation or induction fields.

Triaxial: Refers to a three conductor cable with one conductor in the center, a second circular conductor shield concentric with the first, and the third circular conductor shield insulated from and concentric with the first and second, usually with insulation.

Tubing: A tube of extruded non-supported material.

Twisted Pair: A pair of wires twisted together, usually standard low-speed communications wire cables.

UG: The two-letter designation that precedes the number on connectors for coaxial cable. It is an abbreviation for Universal Government.

UL: Mark of approval issued by Underwriters Laboratories, Inc.

Ultraviolet (Fiber Optic): A range of electromagnetic waves in the non-visible spectrum, with wavelengths from 10 to 400 nm (shorter than visible light).

UPC (Fiber Optic): A term describing a specific fiber optic contact polishing protocol (process), yielding improved return loss.

Volt (V): Unit of electromotive force. It is the difference of potential required to make a current of one ampere flow through a resistance of one ohm.

Voltage: The term most often used in place of electromotive force, potential, potential difference or voltage drop, to designate electric pressure that exists between two points and is capable of producing a flow of current when a closed circuit is connected between the two points.

Voltage Breakdown: A test to determine maximum voltage across an insulated wire before electrical current leakage occurs through the insulation.

Voltage Rating: The highest voltage that may be continuously applied to a wire or cord in conformance with standards or specifications.

Voltage Standing Wave Ratio (VSWR): The ratio of the maximum effective voltage to the minimum effective voltage measured along the length of a mismatched radio frequency transmission line.

Watt (W): Unit of power or work done at rate of one joule per second or rate of work represented by current of one ampere under a pressure of one volt (volt-ampere).

Wavelength: The distance measured in the direction of propagation of a repetitive electrical pulse or waveform between two successive points that are characterized by the same phase of vibration (one cycle).

Wiping Action: The action that occurs when contacts are mated with a sliding action. Wiping has the effect of removing small amounts of contamination from the contact surfaces, thus establishing better conductivity.