[TZ] Curious about 3 phase power

[Tom Spencer]

Maybe, maybe not. (The pin arrangement does denote the current rating, 
though)

http://en.wikipedia.org/wiki/NEMA_connector

NEMA 5-20 (North American 20 A/125 V grounded)

This is a 20 amperes receptacle; type 5-20 A has a T-slot for the 
neutral blade which allows either 15 amperes parallel-blade plugs or 20 
amperes plugs to be used.

a 240v socket will be a four-wire plug, usually. Not always, though - 
but a 240 3-wire plug and socket are made so you cannot get a 120V plug 
in one.... theoretically.

All NEMA 6 devices are three-wire grounding devices (hot-hot-ground) 
used for 208 V and 240 V circuits and rated for 250 V maximum, with the 
6-15, 6-20 and 6-30 being grounding versions of the 2-15, 2-20 and 2-30, 
respectively. The 6-15 resembles the 5-15, but with collinear horizontal 
pins, spaced 23/32 in (18.256 mm) center-to-center. The 20 A plug has a 
blade rotated 90°, and the 6-20R receptacle may have a T-shaped hole, to 
accept both 6-15P and 6-20P plugs.

NEMA 5-15 hot and neutral | |

NEMA 5-20 hot and neutral -- |
Ground>>>>>>>>>>>>>>>> o

NEMA 6-15 hot and hot -- --

Ground >>>>>>>>>>>>> o
NEMA 6-20 hot and hot -- |

Note that standard practice is to mount a 120V socket with the ground 
pin down, and the 240V socket with the ground pin UP; but that 
particular standard may or may not have been followed if the installer 
was a DIY type...

So, check with trusty VOM before plugging something in, OK?

Chester Leediker wrote:
> It is a "220" plug and the pin arrangement represents the current handling capability.
>
> -Chester Leediker
>
> --- steve at theengineeringbureau.com wrote:
>
> From: Steve Lewis <steve at theengineeringbureau.com>
>
> I think you've explained the situation, perhaps the plug for the air
> conditioner will solve any lingering mysteries.  3 wires plugging into an
> outlet that is similar to but not the same as a normal outlet.  The ground
> prong (I'm guessing it's a ground prong) is a little larger than normal, the
> left hand slot is a T shape, and the right hand slot I don't recall.  After
> pulling the plug out of the wall (while laying on the floor) it was a
> problem to get it reinserted.  Does that sound like a 208 receptacle?

-- 
Tom Spencer