LDI Systems
Member
- Location
- Metropolitan Washington, D.C.
Is there a requirement to have a main breaker in the panel to disconnect power to branch circuit breakers when access to the electric service room is only accessible by qualified personnel ?
Sub panels in apartments
- Thread starter LDI Systems
- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
It may not be a code issue specifically, but common sense suggests that if there are no more than 6 breakers in the sub-panel, a main may not be required.
But be careful in this area since many local housing or electrical codes are more restrictive in this area than the NEC itself. (e.g. Chicago).
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
See 240.24(B)(1) if you are talking about a multi-occupancy building.
For a standard building-no.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The apartment building mentioned in the thread title (well, OK, it just said apartments and nothing about the building) seems to bring it under 240.24 all right.
But that just talks about overcurrent devices, plural and does not seem to cover whether this has to be a single main or just all of the individual breakers.
What does raise a question for me is the scope of "protecting the conductors supplying that occupancy". To me, unless tap rules are involved, nothing in the panel in the apartment protects the supply conductors to the panel, just the feeder or branch wiring inside the apartment.
I thought I understood this section until today.
The exception in (B)(1) only addresses the OCPD for the service itself and feeders that supply more than one apartment.
If the question ultimately revolves around doing electrical work in the sub-panel (like changing out branch breakers with the main open versus with the bus energized, versus having the management disconnect the feed to the panel), that gets into a whole different area of concern, since 240 is just talking about OCPDs.
Last edited:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
The apartment building mentioned in the thread title (well, OK, it just said apartments and nothing about the building) seems to bring it under 240.24 all right.
But that just talks about overcurrent devices, plural and does not seem to cover whether this has to be a single main or just all of the individual breakers.
What does raise a question for me is the scope of "protecting the conductors supplying that occupancy". To me, unless tap rules are involved, nothing in the panel in the apartment protects the supply conductors to the panel, just the feeder or branch wiring inside the apartment.
I thought I understood this section until today.
The exception in (B)(1) only addresses the OCPD for the service itself and feeders that supply more than one apartment.
If the question ultimately revolves around doing electrical work in the sub-panel (like changing out branch breakers with the main open versus with the bus energized, versus having the management disconnect the feed to the panel), that gets into a whole different area of concern, since 240 is just talking about OCPDs.
Gold, it's Friday night, I'm tired, and you want me to think hard about this section? Not a chance...
Gonna go play my Wii and relax.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I'll drink to that. Just don't let go of the controller when you swing.Gonna go play my Wii and relax.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
The way I read 240.24(B)(1) is that occupants of any space must have access to all overcurrent devices associated with their space.
This would include the service or feeder breaker located elsewhere on the premises. The exception to that is if there is continuous building management supervision.
If I understand that correctly, there should never be a requirement for a main breaker in a feeder supplied tenant panel, it is optional to have a main breaker though. A panel supplied by a service or feeder tap would follow same rules no matter what kind of occupancy it is and would have a main breaker installed in almost every instance (6 mains rule for services is about the only possible exception)
This would include the service or feeder breaker located elsewhere on the premises. The exception to that is if there is continuous building management supervision.
If I understand that correctly, there should never be a requirement for a main breaker in a feeder supplied tenant panel, it is optional to have a main breaker though. A panel supplied by a service or feeder tap would follow same rules no matter what kind of occupancy it is and would have a main breaker installed in almost every instance (6 mains rule for services is about the only possible exception)
It is a straight forward question. If there is a main feeder breaker (most likely at the meter stack), should a main circuit breaker be included in the tenant load center? I don't think it is required. I do think it is a good idea. I do think it is the first thing to go if there are budget concerns (there are always budget concerns).
Not really, you just added to the question. Where does it say there is a main feeder or it is a meter stack? Maybe there is one feeder powering multiple panels in multiple units. Maybe the main is locked up not accessible to the tenants, maybe the main is right next to the front door of the apartment? Too many assumptions to say a simple yes or no. Just sayin.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I don't see the need for a poll, a "sub panel" never needs a main within the panel. If a feeder tap happens to supply the panel then a single overcurrent device is required at the end of the feeder tap, but it is because it is a feeder tap not because the panel requires a main and it still doesn't need to be installed within the panel it supplies either.
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