120/208 3phase

[electricalist]

I understand its hard to tell me whats going on if I dont provide the right information. The poco did say there was 100k or more without power amd days til its up again. What im trying to learn from this is how to determin what is actually out, what is not and can I/our co do anything to help them establish a way to deal with no phone no comp elect door locks. They panic and I probably would too with employees unable to work and all their customers panicking

 

[GoldDigger]

1. Portable generator
2. Determine, as you have started to do, what circuits are actually working and then rewire temporarily to put critical loads on those breakers.
3. Figure out why phones are nor working. Possibilities include:
Local PBX without power
Internet phones without power to network infrastructure
TELCO power or lines down too.

 

[electricalist]

When I wired houses often we would set panels that had loads the boss considered the generator panel . Some never made use of them others did just because they had the option. I think this customer would want if only a small panel something that powered his main comp phoneboard alarm etc

 

[kwired]

I understand its hard to tell me whats going on if I dont provide the right information. The poco did say there was 100k or more without power amd days til its up again. What im trying to learn from this is how to determin what is actually out, what is not and can I/our co do anything to help them establish a way to deal with no phone no comp elect door locks. They panic and I probably would too with employees unable to work and all their customers panicking

Open phase or blown fuse others are trying to describe is on the POCO primary side of the transformer bank. If you don't get full power in you can't get full power out, you just happen to have the wrong combination out to properly supply the A to C portion of the bank and therefore can not power anything that is 120 volts. Had the POCO lost a different line you may still have at least some 120 volts but may not have all three phases.

 

[electricalist]

I told the customer it could be that his neighbors have 120/208 with 120 on each phase and it appears b ohase is workung . For them at 120 v bur his b phase is 208. Not much that I can do

 

[gar]

141004-1440 EDT

electricalist:

Low voltage can cause some equipment to fail. In particular motors. Disconnect any motors.

Your line-to-line 230 V is probably a solid source. Your labels B and C I believe.

How many kVA are required to provide minimum service. Can you rent a 240 to 240 center tapped transformer of this size or somewhat larger? If so, then turn off all branch circuit breakers. Create a temporary 120-0-120 panel and connect the critical circuits to this panel. Supply this panel from the secondary of the rented transformer. The primary of the rented transformer goes to a breaker in the main panel.

Now you are powering your critical circuits from the one good incoming phase (B to C).

To do this you should probably have help from another electrician familiar with solving this kind of problem. You could do this same arrangement and power the temporary panel from a 240 V center tapped generator.

In the future the customer should define critical single phase circuits, and run these from a sub-panel with a main breaker. Provide a transfer switch to the sub-panel. This transfer switch could in an emergency condition be supplied from any 240 V center tapped source.

.

 

[electricalist]

I was with a co worker and im not knockin him but you have probably met one. Kinda shows up like big show. Checking every disc. Hard in thought . Then like flash tells the customer "you have a power outage" then begins to explain pocos scope of work. Looks like hes all about it but not really

 

[electricalist]

I shut down all disconnects providing power to the building. They have 7 ac that we provided power for so informed him of the damage it can fo to them.