# Ground Question



## LarryHomeowner (May 20, 2018)

Hi All. Question about grounding. No, not the Teenagers 

For about 15 years I've had a Craftsman 6300/9200 watt Generator that has, and still does, work awesome. Since I did not have a transfer switch I of course had extension cords running all over the **** place, and also used a single car jump-start cable to ground the generator to a nearby water pipe.

Since I don't get around so well these days, running cords all over the house was out of the question so I bought a new DuraMax 9500/12000 watt generator and had a new power panel installed (it was due for that anyway) and had a Transfer switch put it. It's actually a Generac combo unit and the switch can be used as automatic if I ever decide to go full standby.

Anyway, now that I have the new panel/transfer switch and will be running a single 50 amp cable from the generator to the panel, do I still need to run a separate ground to the genny, or will the setup pull the ground from inside the panel?

Also, this genny has a 120/240 voltage selector switch. Should i run that in the 240 position so it simulates the power coming in from the power company? The Duramax manual is kinda poopie and doesn't explain this switch well.


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## HarryN (Jun 2, 2018)

There are a couple of ways that these things can be wired, and it depends a little bit on the exact equipment models.

Do you happen to know the model number of the generac transfer switch?

As far as the generator itself:

I am assuming that it is the DuroMax XP12000E

https://www.factoryauthorizedoutlet.com/duromax-xp12000e-12000-watt-18-hp-portable-gas-generator

The way that these are normally wired is similar to your home wiring, some people call it split phase, some times it is referred to as 2 phase. Regardless of the name, the usual configuration is:

- Common neutral
- 2 hot wires out of phase with each other

Similar to how a class A RV is wired:
- 50 amps x 240 vac across the 2 hot wires

In a home, this is similar, but the amperage coming in is higher 100 - 200 amps is common.

_____________________

Just like in a home

- If 120 vac is needed, each 50 amp "leg" is split up

First 50 amps is supplied on each side (hot to neutral)

On the outlets, this 50 amps is further sub divided into a 30 amp x 120 vac and a 20 amp x 120 vac





- 120 vac x about 30 amps on each leg - (hence the 30 amp RV plugs on it)
- 240 vac x


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## HarryN (Jun 2, 2018)

There are some errors in my post above, but I am not quite sure how to edit on this forum to remove the errors. Just ignore the last 2 lines above.

In a home, the ground - neutral bond is provided in the electrical box.

In a generator, usually the ground - neutral bond is the generator frame, but this is not always true - for example small generators often just leave it floating.

Most transfer switches that I have seen deal with this ground-neutral bonding / switching as needed during the installation. You can ask your electrician to be sure.

I would definitely run the 240 vac (2 hots, neutral and ground) from the generator to the transfer switch unless otherwise advised.

If you can, use a neutral just as large as the hot wires, and some locations require the ground to be sized to carry the entire load, not sure if this applies to a generator or not. For 50 amps, might be worth hard wiring it.


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