[TZ] Curious about 3 phase power

[Chester Leediker]

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?

This old motel dates back to at least the 70's which is why I got such a
good deal on an extended room stay.  Folks in the other two motels
(including a Radisson) were probably more unhappy than I was.

-----Original Message-----

If there is 240 supplied, then the power feed is a delta, and both 120 and 
240 are supplied from the secondary of one transformer. Thus, if there is 3 
phase being supplied, there is/was something that required 3phase. Judging 
by what you say, not likely a delta in this case.

On the other hand, if 3 phase is supplied and there is/was no 3phase 
equipment to use it, the service is likely a Y*, supplying 3 legs of 120 
volts-to-neutral and 208 volts between any two of the three 120 volt "hots".

[No 240 here.]
Thus, if one primary phase is tripped/blown, one leg of 120 is out and two 
legs of 208 are out,.
Your idea is perfectly plausible, or the xfmr may be bad...(No, that never 
happens,,,,noooooo.)
M
*There will be 3 xfmrs on the pole, or one large all-in-one cabinet unit on 
the ground.