1200A main problem.

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chris kennedy

Senior Member
Location
Miami Fla.
I got a call that a new 1200A main in a Lakeshore ATS is missing C phase. Electrician at the site is 'sure' he has C phase on the line side from POCO.
Breaker is a CH ND50K 1200A 600V. He has already turned it off and on a couple times and is 'sure' it moves to the fully open and fully closed positions.

Any ideas?
Thanks
 

LarryFine

Master Electrician Electric Contractor Richmond VA
With the breaker closed (on), there should be 0v measured from line to load for each phase. Any voltage is a resistive or open breaker pole.
 

chris kennedy

Senior Member
Location
Miami Fla.
seems like there's some numbers missing matey. arrrrrrrrrrrrr.
Yeah, 277 on the load side C.:grin:

This is an hour from here at a job our company lost. I'm getting this info from the GC. Got a call early this morning from the same site wanting to know if they could put 3 conductors under a lug rated for one 600.:-?
 

SEO

Senior Member
Location
Michigan
Maybe they are starting to rethink about who thay gave the job to. Seems like a lot of questions being directed to you.:)
 

chris kennedy

Senior Member
Location
Miami Fla.
Maybe they are starting to rethink about who thay gave the job to. Seems like a lot of questions being directed to you.:)
I currently have 2 jobs going for these guys and another coming out of the ground in December. Its all government funded so there are factors other than price and reputation involved in who gets the job.

Back to the matter at hand. I have never seen a new breaker this size fail for no apparent reason. No ideas out there people?
 

zog

Senior Member
Location
Charlotte, NC
I see them fail all the time, the manufacturer never tests them, and many times the installer never tests them. But this dosent really sound like a breaker failure to me, more like a connection. Get phase to phase and phase to ground voltages on both the line side and load side of the breaker. Then, like Larry said, take a voltage reading across each phase. It is possible the braided connection internal to phase C failed, that happens sometimes, but the connections would be the prime suspect here.
 

masterinbama

Senior Member
I have had the connection from the main breaker to the switchgear bus connection be loose from the factory. Didn't rear it's ugly(and I do mean ugly head until they tried to bring the 500 ton chiller on line.
 

ceb58

Senior Member
Location
Raeford, NC
Is this a new power up or did something just happen to something that has been powered up for a while? I know it is on a smaller scale but I installed a new just out of the box 100amp 3 pole C-H. Powered it up, no c phase. Line voltage was good. Just a bad breaker.
 

Cow

Senior Member
Location
Eastern Oregon
I had a screwup a while back on an install. I threw the breaker on(CH HMCP 400 amp) into a direct shorted wire. The breaker didn't appear to trip(it was in a pump panel with latching hardware over the handle), it just smoked C phase right out of it.

Long story short I'd make sure your guy megged the wiring on the load side of the breaker to be sure. I'm going to start doing that from now on myself before I throw power to it the first time. Dang, one more lesson learned the hard way...:roll:
 

zog

Senior Member
Location
Charlotte, NC
No sir but Christmas is coming, my address is:

Chris Kennedy
Miami Fl.

Shop early and avoid the rush!
They are so cheap thee days, every EC should have one.


10/4 Curtis, new gear, first time energized. I wouldn't mind being called in to look at this, tomorrow is Friday and this in the Florida Keys. Camping gear, I'm there!:grin:
No acceptance testing?? Perfect reason why it should always be done, even if not in the spec. Now I am even more sure about the connection issue.
 

ceb58

Senior Member
Location
Raeford, NC
10/4 Curtis, new gear, first time energized. I wouldn't mind being called in to look at this, tomorrow is Friday and this in the Florida Keys. Camping gear, I'm there!:grin:
Could be as simple as a bad breaker, sometimes we over think things.
If you need any help, camping I mean, give a shout. Two days of this crap from Ida ready for some sun and warm breezes:D
 

zog

Senior Member
Location
Charlotte, NC
Could be as simple as a bad breaker, sometimes we over think things.
Could be, like I said, if it is a breaker issue it would be the braided connection at the movable contact assembly base.

It amazes me that people don't test breakers this size before they install them.

If you need any help, camping I mean, give a shout. Two days of this crap from Ida ready for some sun and warm breezes:D
Amen to that, enough rain already, weekend looks nice, 70's again and sunny.
 

rgiraldo

Member
Location
FL
I had a problem like this before. When they tried to turn the building on one of the legs was reading under voltage. The tested every thing and nothing. I got pissed and got my meter and found the problem on the main breaker. They did not cut back the insulation far back to make contact.
 
They are so cheap thee days, every EC should have one.




No acceptance testing?? Perfect reason why it should always be done, even if not in the spec. Now I am even more sure about the connection issue.

I have been watching the price of the cameras coming down and features going up. At the rate I see, If I wait another 10 years, the cameras should be free. :D

Actually the $5,000 range cameras are probably good for an EC, but still an expense that is tough these days, without some jobs to help pay for the camera.
 
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