Six disconnect rule

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jdixon

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great falls, montana, usa
I have a water plant that we are upgrading the service on. In 1 alternate proposal we will have 3-12.43kv lines entering the building to disconnects. there are various disconnect to allow power to be transfered from 1 feed to the other in case of problems. It then leaves the building to 4 trnsformers (2-down to 480v, 2-down to 2400v). the 2-480v lines go to the pump building to 2 disconnect. The 2400v lines go back to the switchgear building go through various disconnects to allow power to be trnsfered from 1 feed to the other then go to the pump building to 4 disconnects. At the pump building there are 3 generators (1-480v and 2 combined for 2400v). Would this break the 6 disconnect rule or are generator diconnects not included?
 
If I understand your question correctly, the 6 disconnect rule does not come into play at all. There are two different concepts to deal with. One has to do with the number of energy sources you can bring into a single building. Generally speaking, you are limited to one. But there are exceptions, and you meet several of the exceptions. We can talk about those separately, as they do not directly relate to your question.

The other concept has to do with turning off power to the building from any single energy source. For each energy source, you have to be able to turn off power using no more than 6 devices (i.e., breakers, disconnect switches, etc.). For example, when you bring 480 volts into the pump building, how do you turn it off completely? It seems like each 480 volt feeder into the building has one, and only one, disconnect. One is fewer than six, so you are OK there. Another example is the 12kV coming into the main building. You have three 12kV lines, but let?s look at them one at a time. How do you turn off the first 12kV line? Will you have to turn off more than 6 disconnects, in order to turn off that one line? How about the second 12kV line? Will you need to turn off more than 6 disconnects, in order to remove power to the building from that second 12kV line?

That is the way to look at the installation, in terms of compliance with the 6 disconnect rule. So you tell us, do you comply?
 
What i was worried about was the fact that under 225.30 (a) (6) they are allowed more than 1 power source so to disconnect power to the building would take 3 disconnects at the switchgear building wich would also disconnect utility power to the entire complex. And 6 disconnects and 2 gen set disconnects at pump building. But if each individual line is considered separate than this wouldn't be a issue.:jawdrop:
 
You could have a 4160 volt service to a building, in addition to two 480 volt, 2000 amp services, in addition to a 208 volt service, in addition to a generator dedicated for emergency loads, in addition to a generator for optional standby loads, and have 6 disconnects to turn off each separate service. That would be a total of 36 disconnects to turn off the building completely. Not a great design, but it would be code compliant. Does that clarify your situation?
 
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