6 disconnect rule

[mshields]

I've encountered a 500kVA transformer that serves a building (customer owned). But there are two feeders from this transformer going to different places in the building where those feeders terminate in a CB. So to disconnect power to the building, you need to go to both locations.

Does the 6 disconnect rule require that the disconnects be in the same location making this a code violation?

 

[steve66]

I think there are some special conditions that might allow this per 225.30 exceptions. One includes "documented safe switching procedures".

Also, is it possible there is a 2 hour rated wall between the feeders termination points?

 

[Jraef]

The 6 disconnect rule used to be referred to as the "6 hand rule", meaning you must only move your HAND no more that 6 times in a service equipment room to kill all power. That eliminates your situation applying to that rule in any way. What you have is two separate SERVICES fed from one transformer. Different rules, as steve66 mentioned.

 

[electrofelon]

The 6 disconnect rule used to be referred to as the "6 hand rule", meaning you must only move your HAND no more that 6 times in a service equipment room to kill all power. That eliminates your situation applying to that rule in any way. What you have is two separate SERVICES fed from one transformer. Different rules, as steve66 mentioned.

JR,

I believe he said the transformer is customer owned.

 

[Jraef]

JR,

I believe he said the transformer is customer owned.

The point has to do with Firefighters not having to wonder how to kill power when they enter a burning building.

I've had an AHJ say that's irrelevant, that the power coming INTO a new building is the Service Entrance for that building, even though it was on the same site fed from the same transformer. Got nailed once for not having SUSE labels on a pump station building where the main service feed came into a switchgear bldg, then the pump station was a separate outbuilding 200ft. away. YMMV

 

[electrofelon]

The point has to do with Firefighters not having to wonder how to kill power when they enter a burning building.

I've had an AHJ say that's irrelevant, that the power coming INTO a new building is the Service Entrance for that building, even though it was on the same site fed from the same transformer. Got nailed once for not having SUSE labels on a pump station building where the main service feed came into a switchgear bldg, then the pump station was a separate outbuilding 200ft. away. YMMV

I don't follow you. You said

What you have is two separate SERVICES fed from one transformer

If it's a customer owned transformer, they can't be services or service entrance conductor sets.

Not sure if you are using "services" non literally, perhaps firefighter speak as the power supply to a building....:?

 

[steve66]

I don't follow you. You said



If it's a customer owned transformer, they can't be services or service entrance conductor sets.

Not sure if you are using "services" non literally, perhaps firefighter speak as the power supply to a building....:?

The references I mentioned are for "feeders". There are also some similar (but not exactly the same) exceptions for services.

I also somewhat agree with Jref. I'm not sure why the rules have to be different just depending on who owns the transformer.

Maybe the NEC should be changed to allow a client to designate a feeder from an privately owned outdoor xformer as a "service"?

 

[GoldDigger]

The references I mentioned are for "feeders". There are also some similar (but not exactly the same) exceptions for services.

I also somewhat agree with Jref. I'm not sure why the rules have to be different just depending on who owns the transformer.

Maybe the NEC should be changed to allow a client to designate a feeder from an privately owned outdoor xformer as a "service"?

The key distinction about a service is not who "owns" it, but rather whether the wires are or are not protected by OCPD which matches the current capability of the wires.
In general the POCO OCPD will at best protect the transformer but more likely just serve to prevent a transformer short from taking down the primary circuit.

A secondary consideration is that there is only a grounded conductor, not separate grounded conductor and EGC.

Sent from my XT1585 using Tapatalk

 

[steve66]

The key distinction about a service is not who "owns" it, but rather whether the wires are or are not protected by OCPD which matches the current capability of the wires.

That would make sense, but I don't think that's what the NEC says:

Article 100 definitions: service point includes the serving utility. Service conductors: connect to the service point.

How can these be a service if they are on the secondary of a transformer, and the service point is far upstream on the primary side of a transformer?

I would say they are feeder taps - treated the same as the secondary conductors from any indoor transformer. (By that, I mean treated like any other tap conductors. Of course, the outdoor tap rules would apply if they are outside.)