I am not an electrician, but more than capable of weekend warrior projects at a level that would make high end (and quality) contractors drewl.

Doing an electrical project and have the panel open. The line to my workshop subpanel is 220v 3 wire. The line to the AC unit is 220v 2 wires, No neutral.

(I know you can technically use any neutral although there are problems if it's linked to a different circuit. A few zaps taught me that, thanks to the original wiring of this house).

The AC was redone by a contractor during a remodel about 15 years ago.
When the AC starts there is a loud grunt (can't explain the sound), that does not come from anywhere new the conduit that feeds the AC. Our AC guy says not to worry about, I trust him, but he did not put this in.

Is this right to run 220v for the AC w/o a dedicated neutral ?

Worst is it's 1/2" conduit, so I know I couldn't pull a third wire through there, doubt if even an electrician could.

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KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.

220 doesn't use a neutral. It's the difference in the 2 opposing phases of AC together to give you the 220V. The 110 needs the neutral because it's one side of the 220 + neutral = 110V.

I would think the unit should be grounded though for safety although the ground, again, has nothing to do with the supply of power.

The grount you hear on start up may be the capacitor going bad. This happened to mine and after a while, it won't start at all. Good news is that a $7 cap and about 10 min. fixed it.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

The AC doesn't require a neutral, but should definitely have a ground. All newer 240 volt appliances require a seperate neutral and ground so you aren't returning any current on the grounding wire. The line to your subpanel should also have 4 wires- 2 hots, 1 neutral, and 1 ground and the grounding wires should be landed in a seperate bussbar that is isolated from the neutrals. Depending on the installation your AC could be using the conduit as a ground if it is done properly, but I don't recommend that method and it is no longer code compliant. X 2 on what Kartek said about the noise being the capacitor going south.

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1984 300TD 1981 240D

I would say if you are messing with 220 and asking these questions, time to get a pro.

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MB-less

Well I can handle it, dealing with the FUs the electrician made is the issue.
I was rerunning the 220 to my garage/workshop, had to move the conduit and ended up having to make the line a bit longer.
Thats done and running.
But to show what the electrician did, I kept getting feedback zaps. He tapped the white on my subpanel for the lights on the front of the garage, but the hot comes from the other garage on a different circuit, heck a different panel.
Thats it, I didn't think the 220v circuit vs a 220 subpanel through.
Still have to figure out the grunt, it's not coming from anywhere near the AC or it;s power lines

__________________
KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.

Well I can handle it, dealing with the FUs the electrician made is the issue.
I was rerunning the 220 to my garage/workshop, had to move the conduit and ended up having to make the line a bit longer.
Thats done and running.
But to show what the electrician did, I kept getting feedback zaps. He tapped the white on my subpanel for the lights on the front of the garage, but the hot comes from the other garage on a different circuit, heck a different panel.
Thats it, I didn't think the 220v circuit vs a 220 subpanel through.
Still have to figure out the grunt, it's not coming from anywhere near the AC or it;s power lines.
Been doing this for years though,

__________________
KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.

I've "heard" the wires "rattle" in a conduit when a >5HP motor-circuit starts up or in the case of my transmitters, when the HV is shunted to ground through the "crowbar" circuit.

That's the EMF discharging off the wiring...the wires actually "bounce" inside the conduit. A bit "disturbing" if you've never heard it before.

In your case, you should have, at least, a grounding wire going from the frame of the AC compressor back to the real grounding-buss-bar in your panel. And the other two wires? One going from one-phase to the AC compressor and fastened to L1 and the other wire going from the other phase to the AC compressor and fastened to L2. If your AC compressor is designed right, it should fire right up and you shouldn't be getting any "zips" or "zaps" from it.

If your panel is as screwed up as you're saying it was...it might be smarter to have a LICENSED/BONDED electrician come in and check EVERYTHING OUT (including anything YOU might have done) and get the stuff corrected before wiring anything more in your home. IF a fire should break out and a subsequent inspection by a fire-marshall or any other type of safety authority (including your insurance agent/assign) shows up with wiring errors or the like, you could be on the "hotbed" for all costs associated with the firecall, or even the destruction of your home, if it turns out that there was improper/non-code wiring.

Leave it to the pros and get it all in writing...and make sure you have everything signed off before paying the final bill...put the money in escrow so there's no question you're serious about getting a clean bill of health on your house.

You'll sleep better...cooler and happier that it was done right and within spec..

__________________

M. G. Burg
'10 - Dakota SXT - Daily Ride / ≈ 172.5K
.'76 - 450SLC - 107.024.12 / < .89.20 K
..'77 - 280E - 123.033.12 / > 128.20 K
...'67 - El Camino - 283ci / > 207.00 K
....'75 - Yamaha - 650XS / < 21.00 K
.....'87 - G20 Sportvan / > 206.00 K
......'85 - 4WINNS 160 I.O. / 140hp
.......'74 - Honda CT70 / Real 125
.
“I didn’t really say everything I said.”
. . . . . . . . . . . . . . . . . . ~ Yogi Berra ~

I couldn't agree more, it's one thing to fix what was installed right, it's darn near impossible for even a good diy homeowner to fix stupid and dangerous faults that can be hidden anywhere and everywhere.

It doesn't take much to overload the correctly wired circuits in a 1960's or older home. Think about it, people had a washer/dryer, kitchen appliances, hot water heater and a simple furnace.

If the load is not distributed/balanced between the two legs of 110v you are going to have problems, not to mention the liability if someone gets zapped by your a/c unit.

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"I was a dirty bird, Carol's not grungey - she's *****in" John Milner....American Graffiti

First and foremost remember the work was done by a licensed and bonded electrician.
The work was inspected by a Master Electrician, the village inspector, my neighbor.

Most of the issue's are minor, some are probably related to remnants of the original owners electrical work, a long story. That I have been correcting over the years, I think I fixed the last of them last summer. The AC was installed by the electrician.

220 beyond the basics of wiring an outlet or subpanel type setup is my limit, AC (and it's wiring) is the only weekend warrior work I have avoided.

120 is not an issue, I understand loads, balancing etc. I overwire, code to me is the bare minimum of what I will do.
I do things like everything is #12 wire 15 or 20 amp circuit, tape all switches / outlets, no using quick connects, proper color coding, I normally alternate outlets to two breakers, built in lights on different breaker from outlets, label everything.

At my prior house in the 80s I remodeled, the inspector quit looking after a few minutes I had overdone everything. Lighting (dimmable flourescents I wish I had saved those) were wired with 2 circuits with can lights opposite so if a circuit popped you had lights !

PS this house is from the mid 60s, the electrician upped 100 to 200 amp breaker as part of a big addition, but think about it. Today we may have many more devices plugged in but most use very little electricity compared to their equivalent (if it existed) from the 60s.
Microwave excluded.
Todays TVs use a fraction of the juice of those old monsters, refrigerators, even computers use nothing compared to what they did 10 or 15 years ago.
Other than the whirlpool tub, Microwave and AC I can't think of anything in the house today that uses more juice than it's 60's conterpart.
I've tested a lot of things with a kilawatt, sometimes for fun.

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KLK, MCSE

1990 500SL

I was always taught to respect my elders.
I don't have to respect too many people anymore.

i got one of those kill-a-watts too.it is kindof interesting to see just how much juice some things take and then you can actually figure up what it costs to run over time.great little tool to have.my power company has them to loan out,but i figured i was gonna need it longer then a week so just went to home depot and bought one.

What kind of problems would you expect?

X 3 on the cap being the source of the "grunt".