[sdiy] iec connector confusion

[Dave Magnuson]

----- Original Message ----- 
From: "Eric Brombaugh" <ebrombaugh1 at cox.net>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, October 28, 2008 12:58 PM
Subject: Re: [sdiy] iec connector confusion


> Graham Atkins wrote:
>> I would be careful here. It is my understanding that in the US, your Live 
>> &
>> Neutral are split 50/50 with respect of earth. so your potential ideally 
>> on either leg would be no more than 55V in theory.
>
> This is not true - in the US, the neutral leg of a standard 3-prong 
> single-phase 120V circuit is supposed to be near ground potential, 
> although it may drift from that due to resistive effects between the load 
> and the main distribution point (breaker box) where the ground/neutral tie 
> is. The live leg carries the full 120V.
>
> We also have 240V circuits usually used for heavy load devices like water 
> heaters, stoves, etc. These are essentially two back-to-back 120V 
> circuits, so both legs are 120V from ground. You're probably not trying to 
> use your synth power supply with that.
>
> Eric (in the US, and just _measured_ an outlet to be sure)
>
>

Eric is correct.  In the USA, 120V single phase has a neutral at (or near) 
ground.   If you look inside your breaker panel, you'll see that the neutral 
and ground tie to the same buss bar.

BUT!!!  always treat the neutral with the same caution as a hot.   An 
electrician could easily make a mistake and reverse the wires at the 
outlet... and "hot chassis"  may result.

NEVER tie the neutral to ground in your equipment.  This should only be done 
at the breaker panel.

Dan:   Use a multimeter and verify your pinout.   Measure your outlet first 
(to be certain it's wired correctly)
- The slightly larger flat blade is neutral and approx 0V to ground.
- The smaller flat blade is hot and 120V to ground

After verifying your outlet, plug in an IEC cord and check which pin is 
which at the female end.

Dave Magnuson