Having a hard time sizing wire and breakers for Industrial Machines

[Tesselec]

I read article 670. It seems like none of the nameplates on the machines I need to size wire and breakers for include the information required by 670.3(a). I need to price material for about 20 machines because a shop owner is combining two shops into one at a new location. That is one big problem.

In another shop the nameplate on Tsugami BO326-II says 64 amps. I guess this means FLC of all motors inside that will run at once? The machinist ran it on a 50 amp breaker for three years and never had a problem but now that he is running higher rpm jobs the breaker tripped. Tsugami sent me a installation sheet that said it requires a 95 amp service if combined with the chiller pump and V2 MP pump which is being used. There is a bar feeder wired to it too. The machine has a 100amp breaker on it.

So, to size the wire correctly I guess I can look at specs to find highest rated motor, x it by 1.25, add that to the rest of the flc on machine name plate plus flc of pumps and bar feeder?

If I did this and ran #3 or #2 copper to it can I size the breaker to 100 (because that's the size breaker on machine) + 1.25 x highest motor plus other flcs? That sounds super huge.

It seems like no one can tell me a concrete method of providing power these things and everyone just runs #6 and puts them on 50 or 60 amp breakers.

Also, do all these things come with a breaker inside and is it considered a means of disconnect?

If anyone can suggest a book covering this or a way to learn this stuff I would totally appreciate it. Thanks in advance for anyone taking the time to read this.

 

[electrofelon]

You're not alone, I run into this all the time. It is a pain. sometimes there is no rating given, sometimes it just says a vague "XX amps" and you dont know if that is actual or what your conductors should be. Often you dont know what size breaker to use......I hate having to reverse engineer a machine to figure out circuit and breaker size.

 

[retirede]

We always sized the conductors to match the ampacity of the breaker on the machine. If it had a 100A breaker, we ran 100A circuit.

This is probably overkill at times, but we had zero issues and didn’t spend time trying to calculate it with assumptions due to lack of information.

 

[sameguy]

Bingo, if it isn't your money bigger is better, but if you are bidding or must fit to specific gear openings you need to do the leg work.
As in looking up all the info., calling, guessing, running the code book, looks like you do know what you have to do. Load calculations.

 

[kingpb]

Are all the machines working without problems where they are?

Then base your bid on what is installed now, make sure you provide a clarification with bid to that affect, then if it ends up being different later, you can issue a legitimate change order.

 

[retirede]

Having a hard time sizing wire and breakers for Industrial Machines

Bingo, if it isn't your money bigger is better, but if you are bidding or must fit to specific gear openings you need to do the leg work.
As in looking up all the info., calling, guessing, running the code book, looks like you do know what you have to do. Load calculations.

It was our money, but we had our own plant electricians - no bids.

I’m not sure that the cost of the time spent gathering the information and doing a calculation would be less than the cost of running a 100A circuit vs a 75.

 

[Tesselec]

Thanks for the help!