Did you specify the type of welder you planned on using and the specs. I don't know how they even know to install a 30 amp circuit if you did not give them any specs on what you wanted to use.
How do you know they require 50A circuits? Why didn't you tell the electrician that information? There's no way to guess it. If changes are required, it's on you. It seems odd that car lifts would require 50A circuits though. They are relatively low-power devices. I would have expected that a 20A 240V circuit would be adequate. Since they are motor loads, you only need to size the wire to the motor's horsepower rating, and the breaker can be up to 250% larger. So unless the operating current (as shown in the NEC horsepower tables, not on the motor) exceeds 30A, the #10 wire is fine and you could use a 50A breaker.I just had a new building constructed where the electricians knew that I would need 220v receptacles for welders and electric over hydraulic vehicle lifts. The wiring is complete, but they used 30 amp breakers as well as wire that was not rated for 50 amps, so they've got to replace all wiring and breakers to make them 50 amp circuits.
So my question is: Should it be common knowledge by an electrician that these devices need 50 amp circuits? I'm afraid they're gonna try to stick me with the cost for their mess up.
That is a good question. I will try to find that out. The bank and I are funding this construction (my first) and it's a learning experience. I am building this business for my brother who's been out of work for a year. The "other" shop I spoke of was for hobby, not a job. My brother has been the in between for all of the contractors, as I have another business to run.But why do you think you need 50A circuits? What are the actual ratings on the equipment?
I now agree 100 %.You are both negligent. They never should have done work without knowing what you wanted, and you should not have assumed they would somehow guess correctly.
The best you could hope for is that they might give you a break on the rework, but if push came to shove, you would lose. They can rightfully claim that you wanted them to use their best judgement, and they did.