So obviously this is my first post here, so hello!! Anyways, So I got this new warehouse and I had to go out of town for family issue. I hired an electrician to do some updating electrically while I was gone. It was supposed to be done when I got back, well it was barely started.

So long story short put in a serious bind, I at least need to get a compressor wired up which is 220 21.5 amp max. I have a 40 amp circuit where wiring is exposed and a plug I can put on it. However I have seen two different circuts for a 3 wire 220 setup. One where there is 2 hots and a neutral. The other 2 hots and a ground. I know the available circuit is 2 hots and a ground. However, is there I difference in the motor, or will it work with either set up?

Also, now that I am messing with this, I am looking to understand the whole setup. Will send pics in a few minutes of questions. I am willing tothrow a thank you amount on pay pal for someone taking the time to help

I am not an idiot on wiring, as DC circuits are one of my specialities . Just not a whole lot of experience on ac, so I don't "think" I will set myself or something else on fire lol.

And yes, I have tried to get a electrician out asap but everyone is 5 days out of having time. So if you are an electrician in the Dallas area and have the time, that would be awesome as well

 

Welcome. First you are going to figure out if the motor needs a neutral or is straight 240 and single or 3 phase.

 

Ok, here is the motor specs. I know it's not 3 phase, because the last place I had there was not 3 phase available there. It has a standard plug on it.

Motor specs https://app.box.com/s/jhzxmhm7krasj3cr6ybo8cq2834pz3nf

Plug off compressor
https://app.box.com/s/8ck7lwim0jsy4w9lrzup0hbhmvljvzpg

 

Assuming your electric service is 3-phase, what is the voltage of the service? 3-wire or 4-wire? OR.....do you have a 3-wire 3-phase service AND a single phase service?

Your air compressor, is it single phase or 3-phase?

 

Ok, the motor is a 5 HP single phase. IF you have a 240 volt 3-phase service, you can run the motor from 2 hot legs and 1 ground. The ground is strictly for safety, no neutral wire is required.

Yes, the plug configuration you linked to is fine, but normally I wouldn't recommend connecting a 5 HP motor with a plug type connection. What is amperage of the plug? I'd suggest using a 50 or 60 amp plug

 

Here is the main box coming into building https://app.box.com/s/096m4cf6qg5d8b01vh3cwdj9m8mvydwp

Here is the box that the circuit I was going to wire info comes from https://app.box.com/s/jtcmjhqetn6nkz977kqo8g9fqe28xs48

And here is the junction. It goes to the bottom corner 2 breakers of the breaker panel. It grounds to the metal piping there at that junction. 40 amp https://app.box.com/s/4lj1n2fa38rjnqb412n7lr8ciiupgkn4

 

The plug I have currently is 30 amp and the breaker the 240 wires are running from is a 40 amp. All this was suppose to be redone already, so this will only be for temp so I can finished fabricating this piece for a customer. When I have a real electrician come in, will have if all done proper. I have heard the same thing you recommended as using a 50 or 60 amp design.

I am almost tempted to learn more and do alot of the work myself as I am a diy type person. However, I am worried about the learning curve and time. I have been doing DC for 15 years, just nothing much of ac. I mean I am still trying to understand the wiring of the box. I understand how the circuit runs, the functions of the ground and neutral and the hots. However, still trying to grasp how that ties into the smaller breaker box.

 

It looks like a 400 amp, 120/208 volt 3-phase, 4-wire service, but that should be verified by your new electrician. The panel is badly in need of replacement, it looks like it could be an old GE aluminum bus loadcenter. I couldn't tell which breakers power the circuit you mentioned. It appears all grounding is done with the steel conduits. The motor is actually rated at 240 volts as I recall from your picture, but I think it will still start on 208 volts. I am wondering why the "B" phase to the fused switch is fed with only one conductor while phases "A" and "C" are each fed with two conductors in parallel.

Also wondering how the panel is being fed, there are no wires in the main lugs.

 

I wish I could answer your questions better. I know the main box is a sylvania box, and I think the electrician said it was 400 amps. I took a picture of the junction box that the smaller box runs from. All the wires splice off the main lines coming from the main box. It looks like they had another box at one point that ran something pretty big. They just cut the wires and put them in that lower box I am putting a link to. All the power for the building that goes to the smaller box comes from those wires spliced in through those metal connectors wrapped in tape (I know they have a specific name but don't remember if)

https://app.box.com/s/brmd3pamgdw0ey5y5heixn980ei2o10v

 

Also the circuit that I mentioned. I tracked them down to the bottom right breakers. It isnt the two lowest ones on the right. It's the two lowest ones that have the bar going across

 

And as for the question to the ABC phases, I don't know how to answer that question, as I am unsure the difference in them. I See what you were talking about, multiple lines going to some of them from the mains outside just unsure the difference. Also I don't know what that smaller connection to the right of the box is. I naturally assume that is the ground, however, you know what assuming does. Especially with 400 amps lol

Oh and it does say on the box 240 volts and 400 amps. Though curious what the hp means

 

That must have been an exciting bang.... on the unfused side of the wiring.

Attachment 59905

 

Ha ha ha....good eye!! Yes, it was quite the shock no pun intended lol. When we were first un bolting everything . those main wires at the bottom where it goes to the smaller box. Well one of those junctions, the tape was worn down. So we just barely moved the wire and it made contact. Starting doing small explosions trying to blow the main box off the wall for a solid 8 seconds couldnt see anything, my friend disappeared in the sparks. Funny now, not so much then ha ha. We at first thought there was a break in the wires coming in, so was about to cut main power outside. But then found the contact point at the bottom box, guess it that was the weakest ground area I dunno.

Amazingly though, didn't blow any of the main fuses

 

HP = HorsePower.

You have a lot of updating that needs to be done. You need a competent contractor who can first evaluate what you have and make recommendations. One of the major concerns I have is that your grounding depends strictly on the conduit and I see a lot of rust in the trough and the circuit breaker panel. The rust may compromise the integrity of the grounding.

 

Some observations:

It appears you have a 120/240 volt 3 phase high leg service. Voltage of the B phase (middle wire) to ground is 208 and can not be used for 120 volt circuits. This is why every third space (the B phase) of the panel is open (except for three pole breakers) and why the B phase in the disconnect is fed with only one wire instead of two like the other phases. It was (may still be) common to under size the high leg (wild leg) however the fuse should still be sized to the wire size. (200 amp)

Your service equipment is in very poor shape. I would recommend replacing the whole works. Based on what you have posted so far, I would recommend getting a competent electrician In fact, this being a commercial space you may be required to.

 

I guessed it to be 120/208 volts, but I also suggested it be verified. Regardless, you are right, it is in very poor condition.