15Kw generator on 7.5Kw transfer switch

daybreak1998 · Oct 12, 2013

Howdy,
The same thing applies when you have a 8000watt generator and you plug in something to the standard 120 duplex receptacle on the generator. Just because it can handle 8000 watts, doesn't mean that item plugged in is gonna get it all.

Existing setup has only 7500watts of circuit breakers for those items only. Whether the generator is 5000w or 25,000w.

Hopefully there generator has a 30 amp 120/240 volt L14-30r outlet. Then, they are good to go.

cqaigy2 · Oct 12, 2013

grsthegreat said:
well..not legally true. the wiring for the transfer switch is rated 30 amps...being fed by a device that can supply 62 amps. so there IS a problem. then again, im an electrician so i HAVE to follow the code. An owner doesnt. I have no idea what the actual connected load to the transfer switch is. so im just guessing

That's interesting, seems if the same logic held for your regular main power, you'd need a bazillion <---I made that number up,

amp service/wire because you could theoretically pull more from it. And ditto on all the other circuits and extension cords.

Midniteoyl · Oct 12, 2013

Wow... lotta idiotic thinking here... But, go ahead, let him do it and if something happens, explain to the insurance company how you took non-electrician advice from a tractor forum :confused2:

grsthegreat · Oct 12, 2013

cqaigy2 said:
That's interesting, seems if the same logic held for your regular main power, you'd need a bazillion <---I made that number up, amp service/wire because you could theoretically pull more from it. And ditto on all the other circuits and extension cords.

thats not what im trying to describe. What i was saying was i have NO IDEA what his connected load is on the system. He may have a 7500 watt transfer rated switch hooked up to 6 15 amp circuits...or they might be hooked up to 20 - 20 amp circuits. I simply dont have enough information.

As for the wire size, i didnt make up the NEC reg book, but i have to live by it. I am required to size my feeder wires to the generator. the inspectors dont care what the load is. If i have a 20KW gen set installed, my wires HAVE to be sized to the 20KW rating.

Just cause you can drive 75 in a 35 zone, doesnt make it legal.

grsthegreat · Oct 12, 2013

Midniteoyl said:
Wow... lotta idiotic thinking here... But, go ahead, let him do it and if something happens, explain to the insurance company how you took non-electrician advice from a tractor forum :confused2:

good one.

Coyote machine · Oct 13, 2013

I'm not taking anyone's advice except for the company that makes the transfer switch. Here is what their answer is regarding using a generator rated to higher output then the transfer switch.
I did want to hear people's feedback on my question; that does NOT mean I'm doing electrical decision making based on a tractor forum. Stop assuming what I'm going to be doing- I'll be the one who decides what, AND the answer should send a lot of misinformation to the curb for others looking for the answer to this question.

FROM: Gentran Corporation: Generator Transfer switches for home & business

Can I use a generator whose wattage exceeds the wattage on the Transfer Switch?
NO. While it might be possible to connect a larger generator to the transfer switch, this is an unsafe and dangerous practice. Supplying more than the rated wattage through the transfer switch could damage the wattmeters, damage the neutral wire, and could overheat the main wiring in the transfer switch, which could cause a fire.

The above statement by the company who manufacturers the transfer switch is what the tenant will comply with.

Thanks again to all who contributed. This is basically what I told my tenant at the outset- generator MUST be 7500 watts or less.

Case closed.

CM - out.

Midniteoyl · Oct 13, 2013

Not assuming anything, and that statement wasnt exactly for you..

grsthegreat · Oct 13, 2013

Coyote machine said:
FROM: Gentran Corporation: Generator Transfer switches for home & business

Can I use a generator whose wattage exceeds the wattage on the Transfer Switch?
NO. While it might be possible to connect a larger generator to the transfer switch, this is an unsafe and dangerous practice. Supplying more than the rated wattage through the transfer switch could damage the wattmeters, damage the neutral wire, and could overheat the main wiring in the transfer switch, which could cause a fire.

The above statement by the company who manufacturers the transfer switch is what the tenant will comply with.

Thanks again to all who contributed. This is basically what I told my tenant at the outset- generator MUST be 7500 watts or less.

Case closed.

CM - out.

yup...what i said...i feel vindicated.

but seriously, i was just stating what i know after 30 years of electrical work....installing gensets in homes and even in a 4 story hospital. generator has to size to the transfer switch.

At any rate, glad you got a definitive answer.

Coyote machine · Oct 13, 2013

Midniteoyl said:
Not assuming anything, and that statement wasnt exactly for you..

That's fine, but it wasn't exactly clear which idiots you were referencing. Which 'you' were you referring to in your statement?

Coyote machine · Oct 13, 2013

grsthegreat said:
yup...what i said...i feel vindicated.

but seriously, i was just stating what i know after 30 years of electrical work....installing gensets in homes and even in a 4 story hospital. generator has to size to the transfer switch.

At any rate, glad you got a definitive answer.

Agreed- that's why I posted the definitive answer off their website; don't know why I didn't look for one earlier. I happened to see it on a more recent envelope than the switches vintage, when I was referencing the manual last night.
Yes, I'm pleased to have what both you and I concluded already- rated for up to 7500 watts doesn't mean hook up whatever happens to be nearby!:thumbsup: