Application of the service-disconnecting rule of six switches

[mhi-us]

Hi,

My question centers on a proposed installation of a 24-unit meter pack (each pack contains a meter and disconnect breaker) for a multi-occupancy facility. More specifically, is a disconnecting means required before the 24-unit meter pack?

Figure 230.1 [230.1] implies that service-entrance conductors are located between the terminal box, meter or other enclosure and the service disconnecting means. This appears to be consistent with the definitions of service [100], service conductors [100], and service-entrance conductors [100]. Additionally, Section [230.70] indicates that the disconnect means shall disconnect all conductors in a building or other structure from the service-entrance conductors. Does this imply that a disconnecting means is not required before the 24-unit meter pack?

Any guidance is greatly appreciated.

Note: All provided [references] based on the 2008 National Electrical Code.

 

[david luchini]

I assume you are describing a 24 unit meter-pack on the outside of the building and an underground service lateral. In that case, reading the FPN for the definition of Service-Entrance Conductors, Underground System, it says that where the service equipment is located outside the building walls, there may be no service entrance conductors...

In my opinion, when there are no service entrance conductors, the disconnect rules in 230.70 and 230.71 would still apply (to the service lateral conductors.) You would need a disconnecting means for the 24 unit meter pack, as you would be exceeding the Max number of disconnects in 230.71 without it.

 

[LarryFine]

Welcome to the forum!

More specifically, is a disconnecting means required before the 24-unit meter pack?

Yep.

 

[wawireguy]

Does this multi-occupancy facility have firewalls between tenants or groups of tenants? If so it should be possible to install four seperate services with groups of six disconnects. Don't forget about your house panel. I would find it hard to believe building code would let you have twenty four tenants without any firewalls.

 

[raider1]

Does this multi-occupancy facility have firewalls between tenants or groups of tenants? If so it should be possible to install four seperate services with groups of six disconnects. Don't forget about your house panel. I would find it hard to believe building code would let you have twenty four tenants without any firewalls.

Keep in mind that apartments will typically require fire rated unit separation assemblies. These unit separations are not typically a fire wall and don't necessarily make each unit a separate building.

Remember that not all fire rated walls are "fire walls" that create multiple buildings.

In fact most of the time fire rated walls are either "fire partitions" or "fire barriers" and not actually "fire walls".

Chris

 

[One-eyed Jack]

Keep in mind that apartments will typically require fire rated unit separation assemblies. These unit separations are not typically a fire wall and don't necessarily make each unit a separate building.

Remember that not all fire rated walls are "fire walls" that create multiple buildings.

In fact most of the time fire rated walls are either "fire partitions" or "fire barriers" and not actually "fire walls".

Chris

This is quite true. The term firewall is used much like channel lock pliers. Not all slip joint pliers are created equal.

 

[don_resqcapt19]

In my opinion the only thing that requires a main for this installation is the last sentence of 230.71(A).

There shall be not more than six sets of disconnects per service grouped in any one location.

I think that it is clear that each of the meters is permitted to have up to six means of disconnect.