A 3PDT switch is needed if the neutral and ground are connected at the
generator. The neutral needs to be switched along with the hot legs.
If the neutral is NOT connected to ground at the generator then a DPTD
switch can be use just switching the two hot lines and not the neutral. But
the neutral and ground also need to be not tied together in the transfer
switch box in this case. The only place neutral and ground are common is in
the main breaker box. 4 wires need to be run from the generator. The
generator needs to be bonded to the transfer box and main panel.
A note on ground fault interrupters: they do NOT need any ground connection
to operate properly. They measure the difference in current between neutral
and hot. If any difference they trip indicating a current path between hot
and something other than the neutral lead.
73
Gary K4FMX
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Roger
> Sent: Monday, August 10, 2009 3:37 AM
> Cc: amps@contesting.com
> Subject: Re: [Amps] I need transfer switch information
>
> But what's with the 3PDT switch? I simply ganged two main circuit
> breakers and fed the inputs to the outputs. That's the same way the
> commercial one was built I looked at. I basically switch the whole house.
> I switch both sides of the 220. the ground and neutral normally tie to
> the same spot in the service box and that is the only place they tie
> together. Otherwise ground faults wouldn't work.
>
>
> Charles Harpole wrote:
> > Hey, watch out... u will be powering the
> > whole grid if not careful.
> > Seriously, what about using an automatic
> > change over that also starts the generator.
> > I have seen nice units that do this and
> > cost can not be a factor if you really
> > want to do this.
> >
> > Charles Harpole
> > k4vud@hotmail.com
> >
> >
> >
> >
> >
> >
> >> From: kenw2dtc@comcast.net
> >> To: amps@contesting.com
> >> Date: Mon, 10 Aug 2009 01:37:19 -0400
> >> Subject: [Amps] I need transfer switch information
> >>
> >> I would like to switch out two circuits from my main panel to an
> emergency generator with a manual transfer switch or a contactor. I've
> sketched out a circuit that will do this even when the main panel is live
> and I will need a 3PDT switch.
> >>
> >> Lots of information on the internet about transfer switches except
> what's inside the box. Does anyone know the model number of a transfer
> switch that is a 3PDT ?
> >>
> >> 73,
> >> Ken W2DTC
> >>
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> >>
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> >
> >
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