1. Home
  2. ⏣ General Metalworking
  3. shop wiring?

shop wiring?

In my main shop I have 3 power "busses": one each at 117VAC, 220VAC, 220VAC3ph. The 220VAC (single phase) is run with a 30 amp breaker and 10 gauge copper stranded wire. The wire physically runs from the breaker to a box just the other side of a stud from the panel box, maybe 16", then it splits. One run goes along the west wall of my shop, and the other run goes up and over the ceiling and then down and along the east wall of my shop. On the east side is connected my

5hp air compressor (this is a very real Leeson 5hp motor, this isn't Sears ratings here). On the other side is my welder outlet. I'm basically a one-man shop, so I don't exceed any ratings by running multiple machines simultaneously. This works very well on my 3-phase bus, but it fails on the 220 bus because the air compressor runs when it wants to. If it comes on when I'm welding, the 30A breaker pops. So I've learned to shut off the compressor when I'm welding, no big deal.

I've lived like this for several years. However, I recently got a 60A plasma cutter. This machine needs shop air, lots of it, so I can't shut off the compressor while I'm cutting. And the breaker pops if I don't stop cutting immediately when the compressor kicks on. So I clearly have to install a larger breaker. I'm probably going to replace the 30A breaker with a 50A breaker. The question is, do I have to pull new wires? It would be possible, the wiring is all in surface 3/4" EMT conduit. I'm thinking however, that maybe I can get away with just making the one piece of wiring that goes from the breaker to the J-box where it splits, and keep the 10 gauge runs along the wall, since only half of the current will flow down each wall.

I know what the electrical inspector would say. This shop is never going to get inspected, and if it did, it would instantly fail as would any other shop with a non-UL-approved shopbuilt 3 phase converter wired in. The question is what do I really have to do here.

Thanks!

GWE

Reply to
Grant Erwin
Loading thread data ...

I would definitely pull new wires.

i
Reply to
Ignoramus9075

Code requires dedicated circuits for each of the machines with appropriate wire size and breakers protecting each circuit. Why risk your building insurance by giving your an insurer a way to deny benefit. Even if you do not get it inspected bring it up to code you will rest far easier and still be able to argue about the integrity of the installation.The test in litigation will not be "was it inspected , but was it done to code." from forensics they can determine if it was done right. The cost of doing it right is fairly minimal since you are already contemplating dealing with a wiring deficiency.After all you live in the land of litigation. Just my 2 cents!

Pete

Reply to
Pete

Grant Erwin wrote in news: snipped-for-privacy@corp.supernews.com:

Grant, You need to change out the Jbox for a 2-circuit disconnect. Feed the 50 (I would probably go 60) to the fused disconnect, then peel off of it with the two 10 gauge 30 amp circuits. A 60 amp disconnect with 2 fused circuits is very inexpensive.

Reply to
Anthony

If at all possible, I suggest that you run a new, separate circuit with appropriate breaker and wiring for the plasma cutter. Too many circuits is like having too much fun. You even get more bragging rights.

In rereading your post, it comes to mind that you might be able to simply tap off one leg (not the wild leg) of your 3 phase converter to run the welder. You probably won't be running the mill and the welder at the same time.

Pete Stanaitis

-------------------------------

Grant Erw> In my main shop I have 3 power "busses": one each at 117VAC, 220VAC, > 220VAC3ph.

Reply to
spaco

Breakers are in place to protect the wire-------so---yes---new wire is in order if you exceed 30 amps on a circuit wired with #10 wire. . The advice to install a sub panel with a 60 amp breaker, with two 30 amp circuits makes lots of sense. If you don't buy a Square D panel, you should be able to buy what you need for something like $30.

Harold

Reply to
Harold and Susan Vordos

This is the perfect application for "Broadcast Power"! You might be the first kid on your block.

formatting link

Reply to
Tom Gardner

Yes, you need new wire. Breakers are to protect wires, keep them from looking like light bulb filaments. Actually, they are sized to keep the insulation from melting, not the wire.

Best thing would be to replace the exisiting junction box with a reasonable subpannel, either 60 or 100 amp. For your needs, just set up for 100 amps and be donew with it. Run new wire from your main panel, protect it with a breaker suitable for the wire size. Set up a

240volt/30 amp breaker for the east wall, another for the west wall, a 3rd breaker and outlet for the plasma cutter, another for the phase converter.

My local has an > In my main shop I have 3 power "busses": one each at 117VAC, 220VAC, > 220VAC3ph.

Reply to
RoyJ

I have to second the suggestion for a 100 amp subpanel.

I have a 60A subpanel and it is undersized for about same reason as yours (welding and compressor and possibly plasma cutting). I greatly regret not getting a 100A capable wiring in the first place (2 ga or whatever instead of 6ga).

60 amp is adequate, but not great. With 100A, I would make my welder into a 300 amp welder. Now it is a 200A welder. :-( i

Reply to
Ignoramus9075

Forget running a subpanel. This is already a 60A subpanel off a 200A subpanel off a 400A service.

GWE

Ignoramus9075 wrote:

Reply to
Grant Erwin

Reply to
RoyJ

OK, I picked up a 50A breaker today, and Monday I'll pick up the No. 6 wire and pull a dedicated welder circuit. That should solve the problem entirely.

There is absolutely no need for a subpanel here. The current panel is 14 feet from the box by the welder, and there is new 3/4" conduit running the whole way. I'll just take the old 10 gauge wires loose, tie the end of the 6 gauge bundle to the end, pull out the 10 gauge and use that to pull in the 6 gauge. Done deal.

I'm glad you guys are here to prod my conscience. I don't know how many times I've cautioned guys about insurance not paying. It helps that my good friend is a city inspector, and he told me flatly to run no. 6 wire and he even gave me the 50A breaker.

Grant

Reply to
Grant Erwin

Here's a link to some code info I found helpfull

formatting link

Reply to
Tom Gardner

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.