Need an equipment ground?

[JoeNorm]

Working on a residence which had a meter attached to the transformer about 40 feet from the house. First means of disconnect is at the main panel in the house.
From the meter to the house is a three wire without an equipment ground.

We just installed a new meter/main with overcurrent protection next to the the transformer to replace old meter. First means of disconnect is now at the new meter/main therefore we plan to separate grounds and neutrals at the main panel in the house and make the ground-neutral bond in the new meter/main.

What I am wondering about is if the three-wire feeder to the house without a ground is Ok? Or do we now need to pull in an equipment ground?

thanks

 

[bwat]

Definitely need an egc. That’s now a feeder since it’s downstream from the service disconnect.

 

[JoeNorm]

And there would be no other way to trip the breaker in the meter/main in a ground fault situation without the EGC? Correct?

 

[JoeNorm]

How bout NEC 250.32(B)(1) exceptions?

 

[jaggedben]

How bout NEC 250.32(B)(1) exceptions?

That's a possibility. In my experience it's good to have permitting records of the original installation to prove the part about it being compliant when it was installed. This may be highly dependent upon your AHJ's willingness to agree that the exception applies.

 

[jaggedben]

And there would be no other way to trip the breaker in the meter/main in a ground fault situation without the EGC? Correct?

Not really. If you don't run an EGC, then you keep the existing neutral-ground connection at the house, and the breaker still trips. The most dangerous thing is to not have one or the other, i.e. neither an EGC between structures nor a N-G bond at the down stream structure. Having both is not really so dangerous but is a code violation because normal operating neutral current would run on the EGC and they don't want that.

 

[bwat]

This may be highly dependent upon your AHJ's willingness to agree that the exception applies.

I can’t see many agreeing that the exception applies. Because it’s not so much that the installation was compliant to a previous code cycle and is now not compliant to current code, it’s that the installation changed and what used to be a service is now a feeder.

I’d be interested to hear if anyone here has tried to use this exception for your type of scenario and had success.

 

[JoeNorm]

As important: does the new installation present any more of a danger than the previous?

 

[bwat]

If you keep the N-G bond at the house, then you’re right, it’s a decent question to ask: regardless of code, what’s the difference?

But that’s not the way the exception seems to be worded. It’s a decent idea though and you may get a favorable answer from your AHJ.

On a related note, I do sometimes find it odd how differently services and feeders like yours are treated in the code. For things like this I wonder if I’m trying to put too much logic into the code that just isn’t actually there, or if there are things I’m failing to consider that the CMP has correctly considered. I tend to hope for the later and that there are good reasons for why the code is what it is.

 

[LarryFine]

First means of disconnect is now at the new meter/main therefore we plan to separate grounds and neutrals at the main panel in the house and make the ground-neutral bond in the new meter/main.

What I am wondering about is if the three-wire feeder to the house without a ground is Ok? Or do we now need to pull in an equipment ground?

How and why would you separate grounds and neutrals in the house if you only have a 3-wire feeder?

 

[JoeNorm]

The "how" part seems easy enough. The "why" is another story. I don't know, that's why I am asking questions on this forum. Turns out that I am not going to separate them unless I end up pulling an equipment ground with the 3-wire.

 

[LarryFine]

Agreed. (When I said "how" I meant electrically, not physically.)

There is another thread going on now that mentioned certain instances where a disconnect at the meter may not have to be followed by a 4-wire feeder.

 

[JoeNorm]

So if I leave the G-N bond in the main panel, should it be removed in the new Meter/main?

 

[bwat]

Something that may be a factor is that you actually have an ocpd and not just a disconnect. If I’m thinking of the same thread that Larry is mentioning, that seems to make a difference.

I’m not saying I agree with it, but that seems to be the case.

 

[JoeNorm]

Can you link that thread? Thanks

 

[JoeNorm]

update: I called my AHJ to ask directly about this and he said as long as we have not altered the existing 3-wire or panel inside the house we are permitted to add the meter/main without having to pull the EGC.

Adding the meter/main does not count as "altering" the wires in this case.

 

[bwat]

That’s great news. Thanks for updating on the result.