Garage grounding and bonding

17 years ago

Hello again,

In going over my power supply I developed another grounding question.

The power from the meter on the outside of the house goes into a box or panel just under the meter. It has a 200 amp breaker/disconnect for the 2 hots and the third wire (ground or neutral) just passes through. On the bottom side of the breaker the wires go into my house (200 amp panel) and another set is tapped off to go to my detached garage (100 amp panel). Hence the house and garage power are both supplied separately from that 200 amp breaker panel under the meter. The garage is not a subpanel of the house.

One of the garage breakers (60 amps) runs to another building (woodworking shop) which has a subpanel installed. There are 4 wires between the garage and woodshop (2 hots a neutral and ground).

This 200 amp switch just below the meter is nice since I can completely disconnect all my buildings from the utility with that one switch (at least the 2 hot wires).

My question is: Should the garage panel be neutral bonded to ground (which it is already) and have the 2 ground rods installed (which it does not) just as the house panel is? I assume yes but wanted to check here first.

Also I know the subpanel should not be bonded (which it now is) but does that also need the ground rods installed (presently there are none)?

Thanks again.

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Comments (3)

normel
17 years ago
Each detached building must have a ground rod(s) if it is served by more than one circuit. Each panel served past the service disconnect (200A) is a subpanel. The panel in the house should be served by 4 wires. The garage may be served by three wires if there are no metallic paths between the house and garage. If fed by 3 wires, the neutral and ground are bonded. If it is fed by 4 wires, the neutral is isolated. This is true for both of the subpanels.
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samneric
17 years ago
The power from the meter on the outside of the house goes into a box or panel just under the meter. It has a 200 amp breaker/disconnect for the 2 hots and the third wire (ground or neutral) just passes through. ... This 200 amp switch just below the meter is nice since I can completely disconnect all my buildings from the utility with that one switch (at least the 2 hot wires).

Normel's post about bonding is correct. Just one point - I realize that you didn't ask about this breaker box on your house, but this breaker is supposed to be your main service disconnect regardless of whether or not your house panel has a main breaker. This is also where the house ground rods need to be connected to the neutral and an equipment ground established - not at your house panel. The neutral must be bonded to the disconnect enclosure and must also be disconnectable from the utility at this same point. The usual means to do this is by loosening a setscrew and removing the neutral wire from a lug or bar located in the box. How you are picking up a neutral for the garage panel feeds at this point from a neutral that "just passes through" is unclear.
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welderdaddy
Original Author
17 years ago
The box just below the meter only has a 200 amp breaker. It is not a normal breaker box that you have in your house. It is merely a breaker as a service disconnect rather than a knife type switch. This way both the house and garage can be disconnected with one switch rather than going to each box seperately. It also provided a place to tap into in order to run power to the detached garage.

House panel in the basement has a 200 amp main breaker with the normal circuit breakers below it. Garage has a 100 amp main breaker with 6 circuits below it.

The neutral for the garage is tapped off the neutral line in the box under the meter just as the 2 hots are. Hence 2 hots and a neutral into the house and 2 hots and a neutral into the garage.

So it seems the service disconnect box under the meter should be neutral bonded and grounded by rods, etc according to the above post? That would require a bunch of rewiring. Supposing I don't want to do that could/should I put 2 ground rods off the garage box as a next best solution since I did this for the house already? Hence treating the house and garage as seperate entities both fed by the same meter.

The house (log cabin) was built in 1989 and I got it 3 years ago. I don't want to rewire everything right now to bring it up to current code, I just want it grounded in an acceptable/safe manner as it currently wasn't grounded at all until I added the ground rods off the house box.
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Garage grounding and bonding

Comments (3)

normel

samneric

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welderdaddy
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Garage grounding and bonding

Comments (3)

normel

samneric

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welderdaddyOriginal Author

COMPANY

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GET HELP

CONNECT WITH US

welderdaddy
Original Author