Adding a Disconnect Before the Meter for an Existing Service

[Urchinhead]

I have done some work to correct various code violations at a four-unit building. The 4 units are split between two meters/two panels, and the only gec path is from one of the meters to a water pipe directly above it.

The owner would like me to add a grounding system for the existing service, and leave the two meter/two panel set-up for the time being. My only thought is that I can add a fused disconnect before the meter enclosures, and bond the service at the disconnect. I will then remove existing bonding at the meters, and run my gec path from the disconnect. This will also allow me to add a bank of four meters and panels in the future, without re-splicing the utility connection.

Many older buildings have a set-up just as this, where all bonding is performed at the main disconnect, before the meter banks. Is there anything that I should be concerned with, or is there a better solution that someone has in mind? By local code, the GEC must be protected, so I will run 1/2" EMT from the disconnect to the grounding rods and cold-water pipe.

 

[augie47]

Heavy work for an "apprentice"....
1. You could add grounding from the 2nd existing meter or POCOs point of termination and not need the switch.
2. I would run it by POCO before doing anything. Some POCOs don;t like switches ahead of their meters, or, they at least want their locks on them.
3. Grounding electrode conductors in EMT require a lot of bonding that would not be required in PVC.

 

[George Stolz]

The owner would like me to add a grounding system for the existing service...

Why such a specific request, and why that particular request? :?

Seems like you're making the task more work than requested. If additional grounding is requested, for whatever purpose, it shouldn't necessitate changing enclosures at all. Run GECs to the service disconnects and walk away - what am I missing?

 

[Urchinhead]

PVC is only allowed to be used for underground/slab installations in San Francisco, unless it is a stub-up, 8" or less, inside an enclosure.

It would be easier for me to just pipe out of the panels, but I would like to keep things simple, rather than adding multiple pipes to the two small panels that are fed by the meters. This is an Edwardian building that was built with limited electric outlets, and gas lighting. There is already a mess of plumbing and electrical pipes on the wall of the building where the meters are now.

It sounds like you suggest that I bond at each panel, and jumper the GEC wire between them, piping out of one panel. Is this what you have in mind?

Less work (i.e less bends, etc) is always the sign of a skilled electrician, but I don't want to further screw-up 100 years of poor wiring. A disconnect will make it easier for me to replace the meter bank later, but less work and less money now will make the customer happy.

 

[kwired]

The two meters are probably fed from same service drop or lateral. Run your GEC to that point.

250.64(D)(3) permits this.

 

[Urchinhead]

There is a service drop in 1 1/4" Rigid (That has been illegally finished in 1 1/4" EMT) which feeds the two-meter enclosure, which is spliced inside to the two meter sockets. From the meter sockets are two different panels, one 8"x8" Square D, and the other, a 9" x 12" Challenger.

Can I bring my GEC from the meter enclosure, with the enclosure and the the panels being bonded with the same two wires? I should also replace the 1 1/4" EMT with Rigid, and use a Myers Hub, or at least a bonding bushing. Does this sound like it will fulfill code requirements? I have been looking everywhere in section 250, and have read through the Illustrated Code Book, but there is nothing too specific that I can find . . .

Thank you for all of the help so far.

 

[jaggedben]

Many older buildings have a set-up just as this, where all bonding is performed at the main disconnect, before the meter banks.

Yes, that actually describes my building in SF. Somehow, though, I don't think that if you go through the proper channels you'll be allowed these days to put a disconnect ahead of the meters. What's to stop someone from installing unmetered electrical service between the disconnect and the meters, without notifying PG&E? (Put another way, how will they know that your planned addition of 'a bank of four meters and panels' will actually include the meters?) I think PG&E will not like that.

Where the service for such buildings is more modern, it consists of equipment that integrates the meters, and the section where the service is connected to the meters is either inaccessible as manufactured, or it gets tagged or locked by the utility, or some combo thereof.

I think Kwired is right, you find the common point where the two meters are fed from and ground from there.

By the way, we have passed jobs in SF using a #4 bare GEC with no pipe. Not that a proper pipe job isn't prettier.

EDIT: Started typing before you made your last post. Yes, I think you want to run your ground from the meter enclosure. I'm guessing you'll have to find a suitable listed lug that you can install there, to which (or through which) you can run the grounded conductor and then also connect your GEC.

 

[Urchinhead]

I think that is what I will ultimately do. I will plan to install lugs (depending on what is existing) where I can bond in the enclosure.

In San Francisco, you can run a bare or insulated ground, as long is it is protected, but different inspectors will have different opinions upon what constitutes protection. A locked electrical closet is, "protected," or "guarded."

 

[kwired]

There is a service drop in 1 1/4" Rigid (That has been illegally finished in 1 1/4" EMT) which feeds the two-meter enclosure, which is spliced inside to the two meter sockets. From the meter sockets are two different panels, one 8"x8" Square D, and the other, a 9" x 12" Challenger.

Can I bring my GEC from the meter enclosure, with the enclosure and the the panels being bonded with the same two wires? I should also replace the 1 1/4" EMT with Rigid, and use a Myers Hub, or at least a bonding bushing. Does this sound like it will fulfill code requirements? I have been looking everywhere in section 250, and have read through the Illustrated Code Book, but there is nothing too specific that I can find . . .

Thank you for all of the help so far.

If the two meters are in same enclosure you have it easy. For the grounded conductor there is likely a line lug, two load lugs and an additional lug that typically is used for GEC.

Another reference is to look at 250.24(A)(1) You can connect the grounding electrode conductor to any point between the service drop or lateral and the service disconnect. This is actually has the wording I had in mind and I wanted to mention in previous post but did not find it before.