Electrical Sub-Panel question

[LarryD]

I gotta go with VA Joe on this one Shimon. Even though Washington code requires a seperate "grounding conductor" in the service, it should be bonded to another ground rod.

Isolate the nuetral/ground bus from each other and you will not have to worry about future questions regarding your service, except maybe why ther isn't a permit recorded.

I try to discourage non-permitted work like this simply due to poperty sale that may reveal the violation. A permit only costs about $50 and the inspector can be very helpful. Another aspect to consider is a fire. If your structure burns to the ground due to an electrical short and the insurance company discovers there was never a permit issued...I'm not sure I could afford to replace everything in my garage that I've paid for over many years.

With that said, you're not the only person I know who's added/modified/increased a service without going through channels. Just try to follow code and theroretically you shouldn't have any problems. Ask questions.

 

[CTyler]

Are the codes different in other state with regard to grounding and/or bonding?

I ask because I see conflicting information on the grounding. When we were building our house and shop I had several talks with our electricians on the grounding.

 

[Inspector507]

<font color="blue"> If you run 4 wires a ground rod should be installed and connected to the 4th wire and then no connection to the neutral. </font>

Last sentence in my post. Yes you should still use a ground rod even with 4 wires. Local codes may differ from my area.

 

[Inspector507]

Yes they most certainly are different in other cities/states. My responses are limited to how it is done here. Sorry, I should have clarified that.

 

[SPIKER]

as inspector stated a seperate ground rod for each building is required... as the "seperate building has to have it's OWN ground rod" then the SUB-PANEL requires it to have the ground and Neutral bus bars sepperated inside the sub-panel. then you can run 3 wires or 4 wires either way the ground and Neutral MUST be sepperated in the sub-panel per NEC. most times the 3 wire is all that is ran because you already have to have a speerate ground rod, as required because the seperate building. if it was in same building sub-panel still HAS to have the Ground & neutral bus's sepperated & you HAVE to run 4 wires to feed the sub a ground wire....

ok

Mark M

 

[VA_Joe]

If you only run three wires then the neutral has to be bonded to the detached building's ground rod.

Joe

 

[hitekcountry]

This subject seems to generate such confusion

Spiker

<font color="red"> then you can run 3 wires or 4 wires either way the ground and Neutral MUST be sepperated in the sub-panel per NEC. </font>

That is not what NEC says.

From the main to the sub you run 4 conductors one which is the grounding conductor. You must not bond Ground and Neutral at the sub.
See... NEC 250.32 (B) (1)

From the main to the sub you run 3 conductors . In this case you do bond Ground and Neutral at the sub.
See... NEC 250.32 (B) (2)


Either case you must drive a ground rod at the separate building.

Fred

 

[VA_Joe]

Hitekcountry,

Thanks for pulling out the rule book. Just wanted to add some additional info to your post.

The neutral needs to be bonded to ground in the second building only if both of the following two conditions apply:

1. There is no continuous path (such as a metal water pipe) between the first building and the second

2. There is no equipment grounding conductor between the two buildings.

Typically - for a garage installation - a three wire install requires the ground and neutral to be bonded (with driven ground stake).
If you run copper water pipe between the two buildings then the copper pipe needs to be bonded to the ground lugs in both buildings (the buried copper pipe eliminates the need for a ground stake - although I would still run one). If this is the case - you do not bond the neutral to the second buildings ground.

Joe

 

[_RaT_]

In California, we can no longer use water pipe as a ground in any way since the possibility in the future of that path for ground can be compromised because of non conductive pipe replacing it. We still bond any metal pipe to ground. As you mentioned earlier Joe, my understanding of grounding still does not allow two separate grounds isolated from each other due to a voltage potential. Out West here, it is not uncommon for a 8' 5/8" copper coated metal rod to have enough resitance so as not to be able to trip a 20 amp breaker. The soil can get that dry especially in areas like Arizona, Utah, Nevada, etc. It is why for the most part, a ufer ground is our first ground for new construction. A ufer typically is a 20' piece of #4 (1/2") rebar buried in the bottom 3" of a concrete footing. I admit, grounding can get complicated

 

[Shimon]

Thanks again for the posts. I am getting a permit for this job but I want to have all my ducks in a row before I start.