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My company recently built an apartment house. We put up (I believe) a six gang meter disconnect. Obviously I understand that each meter goes to the individual apartment.

But UNDER each meter is a box with a 100 Amp breaker. And from THAT box we run SER up to a main breaker panel in each apartment.

My question is what purpose does the box with the 100Amp breaker serve? I'm guessing it's some kind of disconnect, but isn't there a disconnect in each main breaker panel as well - so what's the purpose of having two?
 

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Since your panels are not located inside the nearest point of entrance of the service conductors (back to back with the meter bases), the disconnects are required to be outside.
 

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My company recently built an apartment house. We put up (I believe) a six gang meter disconnect. Obviously I understand that each meter goes to the individual apartment.

But UNDER each meter is a box with a 100 Amp breaker. And from THAT box we run SER up to a main breaker panel in each apartment.

My question is what purpose does the box with the 100Amp breaker serve? I'm guessing it's some kind of disconnect, but isn't there a disconnect in each main breaker panel as well - so what's the purpose of having two?
I case of a Fire,the firemen can flip those switches off so there will be no power in the apartments. And also complies with 230.71

Also each panel in each apartment has a disconnect for the occupants


230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or in switchgear. There shall be not more than six sets of disconnects per service grouped in any one location.
For the purpose of this section, disconnecting means installed as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
(1) 
Power monitoring equipment
(2) 
Surge-protective device(s)
(3) 
Control circuit of the ground-fault protection system
(4) 
Power-operable service disconnecting means
(B) Single-Pole Units. Two or three single-pole switches or breakers, capable of individual operation, shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all conductors of the service with no more than six operations of the hand.
Informational Note:  See 408.36, Exception No. 1 and Exception No. 3, for service equipment in certain panelboards, and see 430.95 for service equipment in motor control centers.
 
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