Electrical Engineering - Connecting a 30 amps generator to a 20 amps transfer switch

Author

Connecting a 30 amps generator to a 20 amps transfer switch

denisruc@gmail.com

2007-09-17, 3:25 am

I bought my house from an electrician who had redone the entire
wiring. In particular he'd put a transfer switch for a generator. It's
an EmerGen switch from Connecticut Electric and it looks like it's
rated 20A (There's a L14 male plug with a big "20" above it. I bought
an L14-20 female connector and it seems to fit)

I didn't think I'd ever need it but sure enough last winter our region
experienced its worst wind storm in almost 15 years. We were without
power for 7 days! I was able to secure a generator on the 3rd day but
everybody was out of the L14-xx cords so we had to use regular
extension cords and creative wiring (we hotwired the furnace's blower
and such... nothing horribly dangerous but I'd rather not repeat that
if
I can).

Anyway, this year I vowed to get ready. I checked the generator and
realized that it is rated 30 amps. The front panel has an L14-30
female plug. So I want to hook up my generator, which is rated 30A to
my transfer switch, which is rated 20A. I have an L1420 female
connector for the panel, an L1430 male connector for the generator,
and enough wire (rated 30 amps) to go in between. I can theoretically
build my own cable and hook the generator to the panel

My question is: is it safe?

I believe it should be. However I am also enclined to doubt myself
(the memory of those EE classes in college and the dismal grades
that ensued helps).

I believe that, should my appliances draw more than 20A, the
breakers on the panel will trip. The generator _can_ deliver *up to*
30A but that doesn't mean it will. It only does if the appliances on
the other end actually require that much current. As long as I don't
overload my circuits everything should be fine. I the appliances were
to draw more than 20A then the circuit breakers on the transfer panel
would trip.

Does anybody see any issue with my reasoning? Can I proceed with my
plan or should I replace the transfer switch with one that is rated
30A?

Thanks for your help!

Tim Perry

2007-09-17, 9:25 am

<denisruc@gmail.com> wrote in message
news:1189999123.340314.54540@22g2000hsm.googlegroups.com...
>
> I bought my house from an electrician who had redone the entire
> wiring. In particular he'd put a transfer switch for a generator. It's
> an EmerGen switch from Connecticut Electric and it looks like it's
> rated 20A (There's a L14 male plug with a big "20" above it. I bought
> an L14-20 female connector and it seems to fit)
>
> I didn't think I'd ever need it but sure enough last winter our region
> experienced its worst wind storm in almost 15 years. We were without
> power for 7 days! I was able to secure a generator on the 3rd day but
> everybody was out of the L14-xx cords so we had to use regular
> extension cords and creative wiring (we hotwired the furnace's blower
> and such... nothing horribly dangerous but I'd rather not repeat that
> if
> I can).
>
> Anyway, this year I vowed to get ready. I checked the generator and
> realized that it is rated 30 amps. The front panel has an L14-30
> female plug. So I want to hook up my generator, which is rated 30A to
> my transfer switch, which is rated 20A. I have an L1420 female
> connector for the panel, an L1430 male connector for the generator,
> and enough wire (rated 30 amps) to go in between. I can theoretically
> build my own cable and hook the generator to the panel
>
> My question is: is it safe?
>
> I believe it should be. However I am also enclined to doubt myself
> (the memory of those EE classes in college and the dismal grades
> that ensued helps).
>
> I believe that, should my appliances draw more than 20A, the
> breakers on the panel will trip. The generator _can_ deliver *up to*
> 30A but that doesn't mean it will. It only does if the appliances on
> the other end actually require that much current. As long as I don't
> overload my circuits everything should be fine. I the appliances were
> to draw more than 20A then the circuit breakers on the transfer panel
> would trip.
>
> Does anybody see any issue with my reasoning? Can I proceed with my
> plan or should I replace the transfer switch with one that is rated
> 30A?
>
>
> Thanks for your help!
>

Apparently this is what you have.
http://www.connecticut-electric.com...EGSCutSheet.pdf

Install a 20A breaker between the generator and the switch.

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