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View Full Version : OT; Don't need 220. Need 110 at 20amp. Can I convert it?



danlb
05-23-2010, 04:32 PM
This is sort of on topic,

I have an electrical panel that is full. I need / want to put in a 20 amp 110 circuit for my knee mill and a 20 amp 110 circuit for my small welder.

The only circuit not used is a 220 outlet for my dryer, which is gas, not electric. It has a NEMA 10-30R receptacle. My understanding is that it is dual voltage, no ground.

I was wondering if I could safely replace the breaker with a 110 20 amp breaker and replace the socket with a NEMA 5-20R.

That leaves the question of how to get a ground to the outlet.... There is a grounded 15 amp circuit 2 feet away. Is it a bad idea to bond the ground to that?

Eventually I'll have proper circuits run, but I need to clean out the garage to be able to reach everything. :)

Thanks

Dan

kf2qd
05-23-2010, 04:37 PM
You could do that but you would be much better off pulling that 220 breaker and putting 2 110V breakers in its place and have 2 more 110v circuits that you could use in the shop.

Is there any reason why you need that many circuits in your shop? Are you running multiple machines at the same time under load? Most of the time you can use 1 circuit for multiple machines as they are not in use at the same time.

Evan
05-23-2010, 04:50 PM
The 220 circuit must have a ground but it doesn't need to have a neutral. That gives you three wires. The wiring is probably 10 gauge. You can change wire colours by taping the insulation with the correct colour tape on each wire. You can repurpose the neutral to be a ground by taping the wire green. You are allowed to use either 14 or 12 gauge wire on standard 110 breakers and outlets. If the in place wiring is 10 gauge then in the panel and the outlet box use Marrette connectors to connect the 10 gauge to 12 gauge for the actual connection to the breaker and outlet. The code doesn't mind if you use heavier wire as long as the connections are made with the proper gauge at each end and the correct protection devices are used.

Also, you are allowed to run your 20 amp 110vac welder on a 15 amp outlet but the duty cycle will be reduced. Welders are permitted to overload a circuit up to 200%, spot welders up to 300%.

davidh
05-23-2010, 04:57 PM
why not use the 30amp 220 circuit to go to an aux. 30 amp box ? keeps prying fingers out of the main box. . . .

J Tiers
05-23-2010, 05:16 PM
An electric dryer would allow 4 more circuits, potentially. Depends on the breaker positions already used.

Your 220 Gas dryer would, as mentioned possibly get you 2 120V 20A circuits.

danlb
05-23-2010, 05:35 PM
You could do that but you would be much better off pulling that 220 breaker and putting 2 110V breakers in its place and have 2 more 110v circuits that you could use in the shop.

Sorry, I should have been clearer. I do plan to replace the 220 breaker with a pair of 110. I don't anticipate needing 220 in the near future.




Is there any reason why you need that many circuits in your shop? Are you running multiple machines at the same time under load? Most of the time you can use 1 circuit for multiple machines as they are not in use at the same time.

I do not have any 20 amp circuits in my garage. I have a single 15 amp to run all my machines. I seldom leave one running while working on another. My mill pulls 28 amps at start (highest spindle speed) according to my kill-a-watt, then settles down to under 10 amps.


Also, you are allowed to run your 20 amp 110vac welder on a 15 amp outlet but the duty cycle will be reduced. Welders are permitted to overload a circuit up to 200%, spot welders up to 300%.

200% ??? That's encouraging. I'm finding that MY duty cycle is a few seconds of weld per 10 minutes of setup and inspection. The welder can handle 20% duty cycle. The manual says it needs 25 amps to do thicker metals. :) That was my main reason for pursuing the question. I've also heard that it's a good idea to have a dedicated circuit for the welders to minimize spikes and noise.


You can re-purpose the neutral to be a ground by taping the wire green. You are allowed to use either 14 or 12 gauge wire on standard 110 breakers and outlets.

That makes so much sense. The black becomes hot, red becomes ground and neutral remains what it currently is.

Dan

The Artful Bodger
05-23-2010, 05:39 PM
. You can change wire colours by taping the insulation with the correct colour tape on each wire..

Umm....errrrrr.... I think this is one little tip I will try to forget.

danlb
05-23-2010, 06:11 PM
Color coding wire with tape is a fairly common practice in commercial settings. I've seen it in many buildings.

Dan

MotorradMike
05-23-2010, 06:13 PM
Umm....errrrrr.... I think this is one little tip I will try to forget.

Actually, that is standard practice.

MaxHeadRoom
05-23-2010, 06:50 PM
yes it is allowed under the code as long as it is done at every termination point.
But if you redesignate a neutral as ground, you can no longer use it as a neutral.

The Artful Bodger
05-23-2010, 06:52 PM
OK, but I would never do it as I do not trust tape to stay on forever.:)

Arcane
05-23-2010, 07:03 PM
OK, but I would never do it as I do not trust tape to stay on forever.:)

Inside a panel box it will last almost indefinitely. In the very highly unlikely event that you might find tape fallen off, rewrap the wire with new tape before, or immediately after you disconnect it.

claudev
05-23-2010, 07:04 PM
You can replace any standard 110 volt breaker with a tandem breaker (2 breakers in 1 assembly the same thickness as a standard breaker) and get 2 separate 110 volt circuits in the original single space. In your case, you can even replace your 220 breaker with a 2 tandems or a single quad breaker. This will give you 4 separate 110 volt circuits. Of course you will have to install the actual wiring and assorted components to actually use all these additional circuits. Since I do not know the layout of your panel board or shop I will not try to tell you how to wire up these additional circuits. Just be aware that modern codes require both neutrals and grounds on 110 volt circuits.

(Also note that many older homes and buildings do not have ground connections.)

The Artful Bodger
05-23-2010, 07:14 PM
Inside a panel box it will last almost indefinitely. In the very highly unlikely event that you might find tape fallen off, rewrap the wire with new tape before, or immediately after you disconnect it.

I would be more concerned that someone in the future would cut into the line somewhere and install a mis-wired outlet socket.

Evan
05-23-2010, 08:39 PM
They deserve to be fried if they are trying that on what is (was) obviously a 220 volt cable without checking the termination at the panel first. That scenario is vanishingly unlikely.

You are forgetting and probably not familiar with split phase wiring that we use.

The Artful Bodger
05-23-2010, 09:27 PM
They deserve to be fried if they are trying that on what is (was) obviously a 220 volt cable without checking the termination at the panel first. That scenario is vanishingly unlikely.
Sounds like famous last words.

J Tiers
05-23-2010, 09:46 PM
Also, you are allowed to run your 20 amp 110vac welder on a 15 amp outlet but the duty cycle will be reduced. Welders are permitted to overload a circuit up to 200%, spot welders up to 300%.

The US NEC technically allows that, although the last time we discussed that, I ran some tests, and found that the cable heated up to its maximum temp even in the short duty cycle..... if installed in a hotter environment, it might exceed rated. (of course rated is conservative, but....)

However, your BREAKER may NOT allow that..... depends on what kind it is (brand, and type). Quite a few do not take kindly to overloads, and may trip out. Every time they do trip, they get a tiny bitmore likely to do it again....

Speaking of breakers.... someone mentioned the "2 in one" dual breakers..

I would stay away from those for machines. My experience is that they nuisance trip 5x more than a normal full-space breaker whenever there is any sort of short term overload, as with motor starting, etc.

They were installed in our lab at a previous employer.... we had a LOT of long walks to the breaker box until we got those &^%$! things replaced.

Taping is legitimate.... But for an earth wire, it is better not to tape it green, but to strip it. The only wires that are ever bare are earth, so that is unequivocal.

darryl
05-23-2010, 10:03 PM
As far as keeping a wrap of tape from coming loose, use a small zap strap over it.

danlb
06-02-2010, 09:50 AM
Thanks for all the advice.

It lead to looking up more references, checking code and re-evaluating my needs. I (finally) remembered that one of my motivations was to get the window mounted air conditioner off the circuit that also ran the clothes washer.

I now have two new 20 amp circuits in the garage. One is a new outlet with fresh 12 gauge wire. The other reuses the the heavier wire that used to go to the dryer outlet ( with appropriate pigtails).

Now I can weld while washing clothes and cooling the garage.

Dan

lakeside53
06-02-2010, 12:03 PM
"Now I can weld while washing clothes and cooling the garage"

Now that IS productivity! Turn that man loose on industry:D

Duffy
06-02-2010, 12:11 PM
If you are really worried about falling tape, use coloured shrink tube. A bit more trouble, but a lot more peace of mind.
A tip for adding outlets for your shop, and this applies in North America:- A moulded 3-wire strip, rated at 20 amps 110 volts. You buy it by the yard/metre and screw it to the wall. Individual outlets are snapped in place wherever they are needed, and can be relocated. Special terminations for connecting power and finishing the strip are required, as well as 20 amp breakers. This isnt sold at Home depot; you probably have to go to a wholesaler. I have installed it in BC, Ontario and Quebec, I have an eight-foot length over a work bench and it is really convenient to have all my battery chargers, three lamps, a 1/2 hp and a 3/4 hp motor all on the strip. The CONNECTED ampacity is over 20, but the MAXIMUM RUNNING ampacity is well under 17. I suppose that, to be strictly legal, I should unplug one of the motors, except when I want to use that lathe.

Jim Shaper
06-02-2010, 12:42 PM
Since in order to get another circuit in this 3 wire box, you'd have to pull another wire for neutral, why not leave neutral alone and pull a bare ground wire? No more problem.

In my laundry room, I did exactly what you guys are proposing. I re-purposed one of the hots to a neutral and dropped down to a 20A breaker. I just wanted another circuit because the dehumidifier was overloading the 15A circuit which ran the washing machine and dryer.

danlb
06-02-2010, 01:45 PM
Since in order to get another circuit in this 3 wire box, you'd have to pull another wire for neutral, why not leave neutral alone and pull a bare ground wire? No more problem.


The old wire is only supporting one circuit. I cheated and put the new outlet with the other circuit only 1 foot from the circuit breaker panel. That's centrally located, close enough for running the 12 gage extension cord to where I weld.

The old 220 outlet was already next to my air conditioning, in a wall that is fire-stopped and Fiberglas insulated. I do NOT want to run a fresh ground through that mess.

Black_Moons
06-02-2010, 02:00 PM
Id swap the 240 30A breaker for a 20A, and run some 12-3 where you want the new outlets, then split it off into two 20A 120v circuits (Because 12-3 has 3 conductors+ground, you have a neutral to turn into 120v circuits)

You WILL kick yourself sooner or later if you only have 120v 20A circuits in your shop and no way to safely get 240v at 20A (like a big compressor, welder, or 5hp any thing WILL require)

danlb
06-02-2010, 07:52 PM
Id swap the 240 30A breaker for a 20A, and run some 12-3 where you want the new outlets, then split it off into two 20A 120v circuits (Because 12-3 has 3 conductors+ground, you have a neutral to turn into 120v circuits)

You WILL kick yourself sooner or later if you only have 120v 20A circuits in your shop and no way to safely get 240v at 20A (like a big compressor, welder, or 5hp any thing WILL require)


That is probably correct. I'll add it to the list of "improvements" to be made when I have the generator transfer switch wired in. A sub-panel just for my equipment would probably be in order at some point.

Dan

gnm109
06-02-2010, 08:54 PM
The 220 circuit must have a ground but it doesn't need to have a neutral. .


That's good to know. I recently moved my Bandsaw, belt sander and 4" jointer-planer to my upstairs wokshop and I brought 220 VAC up there to run them. I already have ample 110 VAC sockets on the walls but they are on an angle due to the Gambrel roof (Dutch Barn) and I wanted to place a more convenient box nearby.

I can pull one side of the 220 and associated ground to my box. I had been hesitant to do this since I don't have a neutral in with the 220 VAC and I didn't know whether I needed one or not. I have them in all of the other 110 VAC outlets, however. At the time I did the wiring on the barn (1978) there was no requirement for 4 wires on 220 VAC so no neutral. Also, it's not used on my welder.

I recently built a large powdercoat oven and I did use 4 wires on that and I brought a neutral into its power box.

Thanks!

:p