In the USA we generally only have GFIs on convenience outlets outdoors, in
the kitchen and bathroom, and anywhere there is a concrete pad (or dirt)
floor.

Outlets for specific equipment (refrigerator, stove) and outlets in other
parts of the house generally are not GFI protected.

We do have a rule that extension cords used on construction job sites must
have integral GFI protection.

Also, IIRC, hair dryers must have a GFI built right into the plug.

Bob Ammerman


----- Original Message -----
From: "Peter L. Peres" <plp@ACTCOM.CO.IL>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Saturday, November 02, 2002 5:01 AM
Subject: Re: [PIC]: Direct LED connection?


> On Sat, 2 Nov 2002, Sean Alcorn - Avion Sydney wrote:
>
> *>But seriously though, if the US is running at 7mA and we use 30mA and
> *>still see trips on refrigeration equipment, does it come down to our
> *>dirty power that Roman already pointed out? Or is this simply due to
> *>inherent operating characteristics of refrigeration equipment? I am
> *>curious if they run refrigeration compressors through protected
> *>circuits without nuisance trips in the US.
>
> Not from the US but really dirty power can trip GFIs. A common mode AC
> filter before the panel (!) will cure this. Refrigeration equipment has
> on/off cycles of compressors (with lots of turn-on current), contact
> arcing and all the rest, like condensation bridging insulation
> temporarily. If a particular piece of equipment on a circuit causes all
> the faults then it could have bad insulation. GFI trip current is between
> 15 and 30mA in most parts of the world. 30mA is not supposed to go
> directly through someone's heart, it's the total fault current. I can
> witness that up to 150mA will not start fibrillation, although it can be
> very painful afterwards ;-) Maybe in the US the liability issues are
> larger (i.e. someone once injured his spine by tripping on a marmalade jar
> while being electrocuted with 7.2 mA of mains from a partly dismantled
> electric knife with which he was trying to cut off his left ear, and sued
> successfully - so the authorities decided GFI current will be 7.0mA).
>
> Incidentally the resistance required to pass 7mA peak at 120V is about
> 24k, 30mA peak at 240V is under 11k. The 'hand to hand' resistance of a
> normal man is usually over 50k when not wet etc. So you can't fib from
> touching with both hands (at least in theory). Right now I measured 200k
> between left and right hand.
>
> Otoh there are noGFI interrupters on high voltage power supplies and
> inside valved equipment ;-)
>
> Peter
>
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>

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