grounding at emergency disconnect

P

pipe_bender

Senior Member
Location
Boston
Occupation
Electrician
I have a job coming up where I'll be changing out the service to a very old duplex, installing meter pack (two meters two main breakers) and re-feeding a interior panel. Its a duplex and right now it has a
single riser to a double meterbase outside and a main service panel in each basement fed with a SE cable (3-wire).

There is a ground rod and metal water pipe in the basement of each duplex.
Yes I dont know how they drove ground rods in basements here but not the first time I have seen it.
There are plans to add a PV system to each roof if that affects your opinions on anything.
Is there any way i can keep the SE cable and service disconnects in the basement and call the meter pack a EM disconnect?
I rather not mess with the existing panels.
Thanks
 
It will make the solar easier if you have the service disconnect outside, with the MBJ and GECs all terminate outside. I would also add a gutter or box out of each service disconnect before you refeed the panel so that the solar guy can tap there and just needs to install a fused D/C outside for each.

I would put in a GEC ground bar in the basement to terminate the existing electrodes and then one PVC piped through to the outside to a box and the PVC piped separately to each service disconnect.

If you don't want to mess with the existing panels then you might need to do something like the enhanced content of 250.28(D) in the 2020 NEC (handbook or NFPA link). You will bond the neutral to the EM's case and to the conduit entry (if metal per blah 250.82 or something). That conductor is called the SSBJ. And don't forget the stickers or the solar guy(s) will just think that is the service equipment. All the GECs will need to be bonded to the neutral in the same location to avoid objectionable current. I always suggest installing a GEC ground bar to avoid just that. Then all you need to do is run your GECs from that bar to the service disconnect neutral bar. You will need to remove the green screw in the meter pack. Well, sort of. It is a little discrepancy of 250.102 & 250.28. Where the main bonding jumper and system bonding jumper are a screw it needs to be green. But a SSBJ is not required to be green and it doesn't say that it can't be green. But people usually take the green screw to mean MBJ and you wouldn't want that.
 
pipe_bender said:
...Is there any way i can keep the SE cable and service disconnects in the basement and call the meter pack a EM disconnect?
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You could do it that way. The solar company may hate it. Be nice and ask them what they prefer and work it out with the customer. Without being able to see from here how much if a pain it would be to replace the SE cable with 4-wire, or to run the PV to the existing panels, it's hard to say what is most prudent.

I could see calling the breaker at the meter the emergency disconnect which would allow a tap on its load side to be a supply side connection for the PV, with PV service disco on the outside. Weird way to take advantage of 230.85 but as far as I can tell totally legit. One problem is the PV disco grounding would have to be taken to the existing rods (and that also creates a parallel neutral path which is arguably allowed but ... not great.)

Elect117 said:
It will make the solar easier if you have the service disconnect outside, ...
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I disagree that we can say from here without more info.
 
As we discussed in the recent thread a EM disconnect and a service disconnect make it a building fall under 250.64(D) even a single family dwelling (SFD)
While I like this idea a common ground bar outside the panel:
Elect117 said:
I would put in a GEC ground bar in the basement to terminate the existing electrodes and then one PVC piped through to the outside to a box and the PVC piped separately to each service disconnect.
Click to expand...
How would that work with 250.64(D) 1-3?
 
WD40 said:
As we discussed in the recent thread a EM disconnect and a service disconnect make it a building fall under 250.64(D) even a single family dwelling (SFD)
While I like this idea a common ground bar outside the panel:

How would that work with 250.64(D) 1-3?
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250.64(D)(1)(3)? and 250.64(F)(3)
 
I think the only thing that would not allow you to call the disconnects at the meter center "emergency disconnect, not service equipment would be if the meter center is listed as suitable only for use as service equipment. 230.85(B)(2) or (3).
 
Elect117 said:
250.64(D)(1)(3)? and 250.64(F)(3)
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Thanks so doing it that way there is a common ground bar mounted the basement, not in any panel, the various GEC's land there, then the main GEC from that ground bar goes out to the emergency disconnects (one meterpack)
Then in the existing basement service panels there are no bonding jumpers or grounding electrodes landed, and the equipment ground bar and panel is bonded only to the existing neutral in the SE cable.

Deltaforce said:
It AHJ call, see 230.70(A)
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230.70(A) is met.
kwired said:
I think the only thing that would not allow you to call the disconnects at the meter center "emergency disconnect, not service equipment would be if the meter center is listed as suitable only for use as service equipment. 230.85(B)(2) or (3).
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That section is very weird, I am not sure if its followed by other EC's around here, but your absolutely correct its printed in ink.
My boss was ignoring it, or thinking he would re-label it, or just AHJ would not notice or care, I'll ask him.
Also its very hard to find that info looking in PDF catalogs or online is a meter pack "suitable only for use as service equipment" or "suitable for use as service equipment". Even calls to tech support they get confused, I did open one up at the supply house and it does have that "only" on there.
 
pipe_bender said:
Thanks so doing it that way there is a common ground bar mounted the basement, not in any panel, the various GEC's land there, then the main GEC from that ground bar goes out to the emergency disconnects (one meterpack)
Then in the existing basement service panels there are no bonding jumpers or grounding electrodes landed, and the equipment ground bar and panel is bonded only to the existing neutral in the SE cable.


230.70(A) is met.

That section is very weird, I am not sure if its followed by other EC's around here, but your absolutely correct its printed in ink.
My boss was ignoring it, or thinking he would re-label it, or just AHJ would not notice or care, I'll ask him.
Also its very hard to find that info looking in PDF catalogs or online is a meter pack "suitable only for use as service equipment" or "suitable for use as service equipment". Even calls to tech support they get confused, I did open one up at the supply house and it does have that "only" on there.
Click to expand...
If it has a removable bonding jumper it possibly suitable either way. Permanently bonded grounded conductor units will likely be suitable only for use as service equipment. Some manufacturer specifications can be more difficult to even impossible to find such information, shame on them they should know people will need to verify such information at times.

Also if more then six meters it about has to allow for a service disconnect ahead of it. Modular type units will fit this as they typically need a separate mains module which can be main lugs or a service disconnect module.
 
kwired said:
If it has a removable bonding jumper it possibly suitable either way. Permanently bonded grounded conductor units will likely be suitable only for use as service equipment.
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I see thanks I was wondering what the difference was with the "suitable only" vs "suitable".
 
pipe_bender said:
I see thanks I was wondering what the difference was with the "suitable only" vs "suitable".
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Meter-main type devices often have permanent bonding of neutral to can and if so are suitable only for use as service equipment. Additonal grounding bars would not be electrically separated from the neutral if you used it for a non service application.
 
Deltaforce said:
How?
Service disconnect in basement not at nearest entry point of service as required in 230.70(A)
SE cable unprotected as result
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Can't tell that from the info provided. SE cable could go down the outside structure and LB into the back of the panel in the basement which is "nearest point of entry". Typically in basement service panels, they come through the sill plate and there is is some conductor going down the interior wall. But if that was done the locality probably has a rule allowing a limited distance of service conductor inside the building. However, my last house had a daylight basement and the service conductors came from the meter and through the basement directly into the back of the panels.
 
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