NEC 240.24(B) Location in or on Premises.

So if a tenant had it's own MCB on his panel and access to the utility closet, they should be okay?

Or having a MCB on thr Panel okay and not worrying about the upstreaming service to the utility closet?


However, how about Space B split in half to become Space C.

Can Tenant C Rooftop Breakers remain in Space B Panel if Space B and landlord are okay with it?
 
So if a tenant had it's own MCB on his panel and access to the utility closet, they should be okay?

Having a MCB in the tenant panel accomplishes nothing, but yes the tenant would need access to the breaker supplying the feeder to their unit, unless it meets the exception for being under management supervision.

Or having a MCB on thr Panel okay and not worrying about the upstreaming service to the utility closet?
as the wording currently is, it appears a tenant needs access to all ocpds that supply their unit, all the way up to the service disconnecting means. Again, having a MCB in the tenant panel does not accomplish anything.


However, how about Space B split in half to become Space C.

Can Tenant C Rooftop Breakers remain in Space B Panel if Space B and landlord are okay with it?

My reading of 240.24(B) is they would not require access to HVAC breakers serving RTU's
 
Rephrasing something I mentioned earlier, I would not want the tenant to have the ability to reset the feeder breaker upstream of their panel. If that breaker tripped, something is significantly wrong, and the tenant is unlikely to be able to discern whether resetting the breaker is safe.
Be that as it may, the current wording of 240.24(B) requires what you do not want. And if the upstream breaker and the downstream breaker are not coordinated, the upstream breaker could easily trip before the downstream breaker.

So maybe 240.24(B) should include an exception for when breakers are properly coordinated.

Cheers, Wayne
 
as the wording currently is, it appears a tenant needs access to all ocpds that supply their unit, all the way up to the service disconnecting means. Again, having a MCB in the tenant panel does not accomplish anything.

If Space C is treated as a sub-tenant of Space B, we can install a submeter and disconnect in Space B. Space C would then have a MCB feed from the disconnect in Space B.


My reading of 240.24(B) is they would not require access to HVAC breakers serving RTU's
But why isn't a Rooftop Breaker consider a OCPD if you need to do maintenance on the Rooftop unit
 
If Space C is treated as a sub-tenant of Space B, we can install a submeter and disconnect in Space B. Space C would then have a MCB feed from the disconnect in Space B.
.

I personally see nothing in the wording the allows a "main breaker" to "reset" or be a new beginning for the conductors that serve a tenant. Besides, have you looked at 230.72(C)?

But why isn't a Rooftop Breaker consider a OCPD if you need to do maintenance on the Rooftop unit

It is, and not sure what that has to do with anything. We have been talking about access to OCPD's serving a tenant space.
240.24(B) says:

"(B) Occupancy. Each occupant shall have ready access to all overcurrent devices protecting the conductors supplying that
occupancy, unless otherwise permitted in 240.24(B)(1) and...."

I would not consider conductors serving an RTU to be "conductors supplying the occupancy". I guess that could be up to interpretation since the conductors supply an RTU which supplies air conditioning and heating to the unit, but I guess I don't see the conductors as supplying the occupancy.
 
I see that several of you disagree with me. I accept that, but I will still stick to my interpretation. I will try to say it one more time, and I hope I am clear enough. I doubt this will change anyone's mind. Nevertheless, here it is:

240.24... talks about conductors supplying the occupancy. I believe (and here is where the disagreements originate) the "occupancy" exists only downstream of the tenant's panel's main breaker or main lugs, as appropriate. It is the circuit breakers within that panel that protect the occupancy's conductors. Upstream of that panel, everything belongs to the building's owner, not the tenant. The tenant panel's upstream feeder breaker protects the building's occupancy, not the tenant's occupancy.
 
I see that several of you disagree with me. I accept that, but I will still stick to my interpretation. I will try to say it one more time, and I hope I am clear enough. I doubt this will change anyone's mind. Nevertheless, here it is:

240.24... talks about conductors supplying the occupancy. I believe (and here is where the disagreements orriginate) the "occupancy" exists only downstream of the tenant's panel's main breaker or main lugs, as appropriate. It is the circuit breakers within that panel that protect the occupancy's conductors. Upstream of that panel, everything belongs to the building's owner, not the tenant. The tenant panel's upstream feeder breaker protects the building's occupancy, not the tenant's occupancy.
Who is this and what have you done with our beloved Charlie :mad: ?!?! Our Charlie who "Charlie's rule" is named after?!?!

Charlie, consider a feeder that begins at an electrical room in a building, runs down a hallway, and into an occupancy, say "turbo encabulators R US". Is that feeder "conductors supplying that occupancy". Yes or no.
 
Thanks for the kind words, electrofelon. I am still he.

If in your example this is a tenant business within the building (as opposed to being part of the building's owner's work space), and if the feeder supplies the tenant's panel (which I infer it does, since you used the term "feeder"), then my answer is "no."

As I said before, I don't want the T. E. R US tenant to have access to the electric room, nor would I expect the building's owner to provide continuous supervision. I believe the risk of a tenant being irate over losing power to their whole space is far less important than the risk of a fire or electrocution resulting from an untrained person resetting power to what could be a severely damaged panel.
 
Thanks for the kind words, electrofelon. I am still he.

If in your example this is a tenant business within the building (as opposed to being part of the building's owner's work space), and if the feeder supplies the tenant's panel (which I infer it does, since you used the term "feeder"), then my answer is "no."

As I said before, I don't want the T. E. R US tenant to have access to the electric room, nor would I expect the building's owner to provide continuous supervision. I believe the risk of a tenant being irate over losing power to their whole space is far less important than the risk of a fire or electrocution resulting from an untrained person resetting power to what could be a severely damaged panel.
I do agree that probably the potential negatives of an untrained person having access to feeder and service breakers likely outweighs potential positives. Perhaps the code writers should consider that. I guess we will have to agree to disagree on whether the feeder supplies the occupancy ;)
 
I never said that the feeder does not supply the occupancy!

Back to Charlie's Rule, the code talks about protecting the conductors that supply the occupancy. I contend that the feeder breaker does not protect the conductors inside the occupancy. OK, I inserted the word, "inside." But that is what I believe the intent to have been.

As I said earlier, the feeder breaker is likely to be rated 100 amps or higher. Most of the conductors "inside" the occupancy are rated 20 or 30 amps. They would not be protected by the feeder breaker. Thus, the feeder breaker does not protect the conductors serving the occupancy.
 
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