120/240 panel on 480 system

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electrofelon said:
On a scale of 1-10, how bad is it to have a QO panel on a 277/480 system? Think it will work fine as long as there are no faults? Predictions of what will happen if there is a fault/short circuit?
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No way, it has a L-G rating of 120v and L-L of 240v. You are asking that 277v L-G and 480v L-L is allowed? I don't think so. To do so it is in violation of the panels rating.
The worst that could happen is the arcing would occur L-G and/or L-L creating a terrific arc fault.
 
Right its clearly a code violation, but what will happen? Could a breaker just blow out during normal use? Will it still clear faults at the appropriate current level? Maybe it will clear a fault but be destroyed in the process?

Several months ago I gave someone a price to run a 100 amp 277/480 feeder to a machine shop. It was about a 180 foot run through an old timber frame building - not a simple run by any means. They didnt think they could afford it so I looked into doing the run with aluminum MC and found some 5 wire #1 al MC that was cheaper than pipe and THHN not to mention the labor savings. Gave them the new lower price and didnt hear anything for a while. Send them an email offering to tell them what they needed and they could pick the stuff up and do most of the labor and I would make the connections - I was busy then and didnt really need the work and they were setting up a big glass/welding/machine shop for artists which I thought was cool so I wanted to help them out. Never heard anything. Poke my head in there the other day and see that they took care of it: Ran #2 NM thru 1 1/4 EMT and used a 120/240 load center on the load end. Anyway, I have never seen or considered using a 240 panel on a 480 system and just curious what might happen here....
 
I cannot believe any of you are really asking what can happen.

The darn thing can blow of the wall and in your face in a fault. :?
 
electrofelon said:
On a scale of 1-10, how bad is it to have a QO panel on a 277/480 system? Think it will work fine as long as there are no faults? Predictions of what will happen if there is a fault/short circuit?
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Not having any overcurrent protection at all also works, as long as there are no faults:eek:
 
electrofelon said:
Please reread my description. I did not help, propose they do this, supply parts, pull a permit or anything
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I just read you words of your Op is all. Did you you include this in the OP?
I would suggest that if it were to be done you can get the biggest bang for the buck if you fire it up on the forth of July.
 
electrofelon said:
Please reread my description. I did not help, propose they do this, supply parts, pull a permit or anything
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Send them an email offering to tell them what they needed and they could pick the stuff up and do most of the labor and I would make the connections
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But your honor here is his E-mail. He told me what to get and do. Now what's it going to cost you to prove you didn't?

I say all this to bring home a point. You will run into customers like this throughout your life. You give them a price to do a code compliant install and walk away. Don't stand there and say " well I can run mc cable and set the panel here and it will save you some money" Now the only thing they have heard is save money so they go out, as they have done, and come up with some jacked up crap waiting to explode. And when it dose the blame game begins and you are the star of the show.
 
He is not responsible unless he provided wrong material list.

As I understand here he gave no list. There was a offer to though.
 
ceb58 said:
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But your honor here is his E-mail. He told me what to get and do. Now what's it going to cost you to prove you didn't?

I say all this to bring home a point. You will run into customers like this throughout your life. You give them a price to do a code compliant install and walk away. Don't stand there and say " well I can run mc cable and set the panel here and it will save you some money" Now the only thing they have heard is save money so they go out, as they have done, and come up with some jacked up crap waiting to explode. And when it dose the blame game begins and you are the star of the show.
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Yes, I know what you mean. At a meeting with German engineer for a very large and well know international electrical equipment manufacturer where I stood firmly behind the limitations of a piece of electrical equipment that I was selling him. He became quite argumentative irate with me begging to differ. I remained quite firm in my position regarding the limitations of my product to the point where he sprung up from his chair and stompted out of the room when I told him something that he was unwilling to hear.
 
Sierrasparky said:
He is not responsible unless he provided wrong material list.

As I understand here he gave no list. There was a offer to though.
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And that was my point. Prove he didn't tell them what to get.

By no way am I saying that the OP did any thing wrong or gave these clowns any type of material list. All I am saying is in situations like this you must CYA. If the OP would have just given a price to do the job in a cost effective manner and walked away then the chance of some one turning his willingness to help them out into a "he said" contest would have been none.
 
ceb58 said:
And that was my point. Prove he didn't tell them what to get.

By no way am I saying that the OP did any thing wrong or gave these clowns any type of material list. All I am saying is in situations like this you must CYA. If the OP would have just given a price to do the job in a cost effective manner and walked away then the chance of some one turning his willingness to help them out into a "he said" contest would have been none.
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I sort of get you but we could come up with any number of scenarios where someone could blatantly falsly claim that you did something you didnt whether it be advice or work. Also there are many ways to skin a cat. I have solved some difficult install problems and cut the cost in half of what others were proposing because of my code and equipment knowledge. I dont think there is anything wrong with looking at another way or method. In fact I would be very put off by a contractor who wouldnt work with me and explore other options that might meet my needs better.
 
ceb58 said:
And that was my point. Prove he didn't tell them what to get.
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Prove he did..
I think you are over thinking this.

I am always trying to CMA. However I would not give it a second thought. Other than turn the guy who perfomed the work as it is a serious hazard.
 
Surprisingly, the installation may work for a long time with no real problems. But nobody here is going to predict just how long that will be, or just what will happen when something does fail. Available fault current will make a difference in just how much fireworks you may have if there is a failure, so will trip curves of upstream overcurrent protection. Next question may be just what is upstream, more 240 volt equipment or something rated for at least 480 volts?
 
kwired said:
Surprisingly, the installation may work for a long time with no real problems. But nobody here is going to predict just how long that will be, or just what will happen when something does fail. Available fault current will make a difference in just how much fireworks you may have if there is a failure, so will trip curves of upstream overcurrent protection. Next question may be just what is upstream, more 240 volt equipment or something rated for at least 480 volts?
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I would not want to be the one to find out. Why would you?
 
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