MLO service?

[jrvazzer]

Our landlord is suppying a 3000A breaker for our service. The only issue is that our main board is 200feet away in a locked mech rm. Our electrician is claiming that our main board 3000A does not require a disconnect means if the landlords service breaker that is feeding our MDP has a lock out breaker. So in other words our MDP is a MLO. Can you help me varify this in the NEC.

 

[iwire]

I think the electrician is mistaken, but you still might not need a main depending on the conditions.

240.24

(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 (B)(2).

(1) Service and Feeder Overcurrent Devices. Where
electric service and electrical maintenance are provided by
the building management and where these are under continuous
building management supervision, the service overcurrent
devices and feeder overcurrent devices supplying more than
one occupancy shall be permitted to be accessible only to
authorized management personnel in the following:

(1) Multiple-occupancy buildings

(2) Guest rooms or guest suites

 

[charlie b]

Several issues come to my mind. First, I infer that the "main board" and the service disconnect (the one that is 200 feet away) are still in the same building. If that is not true, then you are one disconnecting means short. Secondly, I surmise that the N-G bond takes place in the locked mechanical room, and that the N & G busses are isolated from each other in the main board. If that is not true, then you have another problem. Finally, I would say that the electrician seems to have had the right answer (no main breaker needed in the main board), but for the wrong reason. That is, the disconnect 200 feet away being lockable is not the reason; Bob gave the reason.

{Side note: I have to agree with Bob tonight. I am only a drive of five hours or so away, and I don't want him coming after me! }

 

[hurk27]

480/277? if so GFP is needed.

 

[jbt260]

If 240.24(B)(1) does not apply, you need a key to the mechanical room. IMO, a 3000A MCB is not required on your MDP. The 3000A feeder would still be connected to YOUR equipment whether it's MLO or MCB.

 

[jrvazzer]

MLO service?

480/277? if so GFP is needed.

480/277v