Electrical Plug Type

If you are in charge of building or expanding a data center, the charts below may help you get the right vocabulary to talk to electricians effectively.

The connectors are designated Male and Female depending on whether they have the plunges sticking out or holes on them, respectively. These names are now changed to the more politically correct Plug and Receptacle. In some literature, receptacles are also called outlets.

Table 1: Most commonly used Receptacles in Data Center.
(NEMA) 5-15P 115 V, 15 AMP, Plug
Standard US 3 plunge household connector.
(NEMA) 5-15R 115 V, 15 AMP, Receptacle (Socket)  
(NEMA) 5-20P 115 V, 20 AMP, Plug
Variation of std US 3 plunge plug, with one "horizontal" connector
(NEMA) 5-20R 115 V, 20 AMP, Receptacle
(NEMA) L5-20P Twist Lock, 115 V, 20 AMP, Plug
(NEMA) L5-20R Twist Lock, 115 V, 20 AMP, Receptacle
(NEMA) L6-20P Twist Lock, 220 V, 20 AMP, Plug
(NEMA) L6-20R Twist Lock, 220 V, 20 AMP, Receptacle
(NEMA) L6-30P Lock, 220 V, 30 AMP, Plug
(NEMA) L6-30R Lock, 220 V, 30 AMP, Receptacle
All the NEMA twist lock presented have essentially the same shape. Their main difference is the diameter of circle, with L5-20 having the smallest diameter, L6-20 being in the middle, and L6-30 is the largest. When checking connector type, it is best to read the engravings on them to see which exact connector it is!

Table 2: Common plug types for Servers.
In IEC scheme, odd numbers are receptors, even are plugs (the ones with the pin out). In a politically incorrect mnemonics, females are odd, males are even.

115V or 220V, 10 Amp.

Standard computer power cord. This plug connects to C13.

A power cord would have a plug on it (left picture).
A socket/receptacle version is used on the surge bars (right picture).


Counterpart of C13.

Standard computer power supply AC inlet socket, or for cord in new cabinet power distribution bar.
A cord with IEC C13 on one end and IEC C14 on the other can be plugged in end to end and work as an extension cord. This is an international standard server power cord, works on 115V or 220V.

The back panel of equipment would have a socket/receptacle/inlet on it (left picture).
Whereas on a power cord, it would be called a plug (right picture).

IEC C15 Slightly diff than C13 in that it has a notch. e.g. used by HP-UX rack servers. This one can plug into C14, but specific C16 socket require this plug connector.
IEC C16 Socket for C15.
IEC C19 Typically used in large servers and chassis for modular/blade server
IEC C20 Male counterpart of C19

Table 3: Other computer plugs.
IEC C5 and IEC C6 Compact 3 plonges connector. e.g. Dell laptop power supply AC input
IEC C7 and IEC C8 Compact 2 plonges connector. e.g. Dell laptop power supply AC input.  


Table 2: Misc.
Sun DB25 serial to RJ45 console port wiring

Recommended Gears

Megger (SMF) MMC850 Multi / single core a.c. clampmeter. Manage a Data Center? Get this "amp meter" and take the guest work out of whether you are overdrawing the circuit! Cost is about $250.

Fluke EtherScope

Ideal power distribution bar for Data Center Cabinet:
Bay Tech PDU21A-30 w/ 12 outlets. Vertical mount. $119
Another model with 24 outlet for $159.

Geist/Flexiduct VRELN080-103C13TL6 8 outlet, rack mount or vertical. $179

Bay Tech Remote Power Control L6-30P w/ 20 IEC C13 receptables, at $563 though.
This allow one to telnet to the power strip and turn on/off an individual receptacle. Also has a build in ampmeter to tell the amount of current draw.


A useful NEMA chart.
Wikipedia IEC Connector
BuyPower.com This site has lots of NEMA and IEC plug/socket drawing and cables, so you can be sure of what you are buying :)
InterPower Another web site selling cables with lot of nice pictures.
Chan's Pinouts Page Very detailed info about many computer plugs pinouts.

Electrical Unit Conversion(formulas for converting between W and VA).

[Doc URL: tiny.cc/plugs]
[Doc URL: http://dl.dropbox.com/u/31360775/psg/plug/plug.html]
[Obsolete Doc URL: http://www.cs.fiu.edu/~tho01/psg/plug/plug.html]
(cc) Tin Ho. See main page for copyright info.

"LYS on the outside, LKS in the inside"
"AUHAUH on the outside, LAPPLAPP in the inside"