I have a question regarding a multiple dwelling unit (3 units). We have a 200A, 3phase, 208v serivce that goes underground into a building to a 200a fused disconnect, tapped to 3 meters and from the meter to the respective disconnect for the unit (2-50A disconnects and (1) 100A disconnect). Are the (3) disconnects after the meter considered "serivce disconnects". I'm a little concerned because we installed 60A main lug "loadcenters" with a 50a c.b., but I don't think they qualify for service disconnects, if that is what they are considered (I didnt do it for the money, space was a real concern). Also, the neutral in bonded in the 200a disconnect, so obviously we don't do any bonding in the disconnects for the units, correct?
Multiple Dwelling Building - Service Disconnects
- Thread starter James13
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
James, welcome to the forum! 
No, the 200a switch is, as far as I know. The meter after the disco shouldn't matter.
Correct. They're sub-panels.
Thank you, I had myself worried because usually we typically do Commerical work (2000a/4000a) services or single residential service drops and i'm not too fimiliar with multiple dwelling services (unless you are going to a meter/trans s from a switchboard). I had to ask, those sub-panels (loadcenters/main cb's) were too cheap (home depot specials) and looked to cheap to make me sleep at night without asking if i was ok.
Here, you might be in a gray area. The first disconnect might be there at POCOs request (somewhat like a cold sequence disconnect) and might be locked and controlled by them. (They often don't want access to equipment ahead of their meters).
For practical matters it makes little difference as you have disconnect after your meters which can serve as service disconnects for your panels anyway.
Often time the tenants have no control over the switch ahead of the meter (locked on and locked closed by POCO) so the switches after the meter become the tenants service disconnects.
For practical matters it makes little difference as you have disconnect after your meters which can serve as service disconnects for your panels anyway.
Often time the tenants have no control over the switch ahead of the meter (locked on and locked closed by POCO) so the switches after the meter become the tenants service disconnects.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
What do you know-- I totally agree with Gus. :grin: The disco before the meter is not, IMO, the service disc and thus another is required after the meter.
Think of this way. If there is a switch at the pole where the trany is would that be the service dsco? A little different I know but...
Think of this way. If there is a switch at the pole where the trany is would that be the service dsco? A little different I know but...
growler
Senior Member
- Location
- Atlanta,GA
Was this job inspected by the local AHJ? There are a few different possibilities. Those meters in the building may belong to the owner and power may be metered by POCO oustside or at the transformer.
When you have a problem like this then talk it over with the local authorities such as the inspecion department and the power company engineers. They can actually come to the job site and see what's there and make a ruling.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Yes, the service disconnects must be bonded to the service neutral
Volta
Senior Member
- Location
- Columbus, Ohio
I would not assume the disconnect on the line side of the meter is not to considered the Service Disconnect, until and unless it is demonstrated that it is exclusively under the control of the utility.
- Location
- Massachusetts
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Okay, if the disco is on the line side of the meter- is it allowed other than if the poco calls for it? If it is allowed and we are suppose to bond the neutral to can up to the first service disco how then can we install a meter after the disco that would have neutral and can bonded? Where would the bonding stop.
Volta
Senior Member
- Location
- Columbus, Ohio
If you have seven or more meters grouped together, it would be required to have a main to get the number to six disconnects or less.
That often would happen on the line side of a wireway with a single main feeding the multiple meters.
Local POCOs may vary in what they allow, I suppose.
Volta
Senior Member
- Location
- Columbus, Ohio
It would then stop at the meter(s). 250.142(B) Exception No. 2 allows for it. Though that doesn't mean the utility will allow it.
e57
Senior Member
- Location
- San Francisco, CA
Harm? Depends... Technically IMO the one MBJ in the main disconnect in this situation is the only one allowed. - The meter is a gray area - due to POCO involvement that the NEC does little to address the conflict/overlap. The POCO may see the metering equipment as their point of connection or service point - and may require a neutral bond there - but the NEC doesn't allow any after the main disconnect/OCP. Added to the fact sometimes it's difficult (but not impossible) to obtain metering equipment without this bond/ground built into it.
PITA is a different story - with 3 main OCP enclosures instead - you would need to tap the GEC into each - quite a bit of extra work - which is probably the reason why the original installer opted to have a single main for all of them instead. (I know I would...)
But even if the disconnect is prior to the metering - it could not be locked or sealed - because the the OCP needs to be accessible to replace fuses etc. Most POCO's accept this - so long as there is little if any way to get conductors into it and conceal them - i.e. one conduit in - one out to the sealed meters.
IMO the "service conductors" END at the main disconnect/OCP the metering is a feeder tap - and the NEC doesn't allow the neutral connection there - the POCO might see that differently. You would need to check their standards for that.
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