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Tapping into 220V line

Posted by criticalmass (My Page) on
Sat, Sep 18, 10 at 12:51

I would like to plug in a light (not sure what type yet), but the only outlet nearby is a 220V outlet for our Air Conditioner. I'm curious to know what my options are. We don't want to run a long extension cord over to the other outlet.

Is there a way to tap into the line to make a 110V outlet, like maybe tap into the black and green wire using pigtails?

Maybe tap into it with another 220V outlet, and just plug in a light that can handle 220V?

Any other option I haven't considered?

Thanks!


Follow-Up Postings:

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RE: Tapping into 220V line

Here is a problem solving guide for your situation, given the information you have supplied above.

1. Determine which of these options is preferable. I have listed them in a probable order of practicality, but your tastes may vary.

A. Buy a new light and run a "long extension cord over to the other outlet".

B. Get by without a new light.

C. Pay an electrician $$$ to install a new 120 volt outlet near the desired location. Plug new light into same.

D. Take vocational classes and learn basic electricity theory and practice so you will know why tapping off of your "220 volt" outlet is not a viable alternative, and how to properly install a 120 volt outlet. Buy the tools and material to do so. Install said outlet, plug new light into same.

2. Act on the option of your choice, after conference with what ever other party constitutes "we".

2a. If applicable, turn new light on and enjoy use of same.


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RE: Tapping into 220V line

DO NOT 'tap into' your 220 line to create a 110 outlet.
I do not recommend long extension cords for extended use, either.
It doesn't sound as though the room is up to code for spacing of convenience outlets. I'd check into having a new circuit run for the outlet, or finding a 110 circuit that can be extended.


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RE: Tapping into 220V line

Any other option I haven't considered?

You can NOT "tap" into a 220v circuit to make a 110v circuit. If nothing else, a 220 has two hots and a ground. 110 requires a hot, neutral, and ground.


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RE: Tapping into 220V line

What's on the other side of the wall where you want the receptacle? Maybe there is a 120 receptacle you tap.


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RE: Tapping into 220V line

I really was not going to follow up this question with a comment, due to wayne440's arrogance turning me off (no pun intended), but I feel I can control myself enough for two minutes.

wayne440, I am fully capable of performing a home run, as I've done so several times in the past, and obviously, I, my wife, my cats, and my house are still here. While I am not a "professional" electrician, this forum is here for a reason: To help DIY'ers with their projects. I was 95% certain the answer to my question was, "No, you can't", however I wanted to check anyway, since I don't know it all. The fact that I posted the message rather than simply attack the 220V outlet shows I at least have some modicum of intelligence. After all, if we all went to school to "learn basic electricity theory and practice", there wouldn't be such a demand for electricians, since most people would be doing their own work. The simple reason I'm not running a new line is because the desire for a light is not strong enough to warrant the work. Ideally, the new outlet I wanted to run was immediately below the AC outlet, which would have been minimal work. However, thank you for the advice.

randy427, the place was built in the 50's, so I'm sure it's not up to code. In fact, it was a nightmare before I started working on it.

joed, unfortunately, the wall in question is an exterior wall (w/ air conditioner)

Thanks anyway, guys. I'll try to take one of Wayne's other suggestions.


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RE: Tapping into 220V line

"the place was built in the 50's, so I'm sure it's not up to code."

Age has nothing to do with "up to code."

Old work is grandfathered despite code revisions.

Does old work meet all the changes to the code since it was installed?

No, but it is only required to meet the rules in effect when it was installed.


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RE: Tapping into 220V line

See what having limited information can do? If you had indicated some knowledge of basic electricity, such as "I could run a new 120 volt circuit, but don't want it that badly", my response would have been much different.

Maybe this. Here is a completely cordless lamp.

Here is a link that might be useful: cordless lamp


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RE: Tapping into 220V line

... let me stir things up a little bit more. :)

We're all saying he can't, but maybe he can.

There was some discussion recently on the ECN forums regarding 120V and 240V receptacles on the same circuit. The consensus there seemed to be that it was legal to do so. If his 240V circuit is actually 120/240 (ie, there is a neutral present), he can tap 120 from it, and provided it's 20A or less, he can tap a "normal" 120V receptacle from it.

He can also have two 240V receptacles on one circuit, meaning his idea of using a lamp that can handle 240V is acceptable, although I'm not sure where he's going to find such a lamp.


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RE: Tapping into 220V line

That's easy enough to check. If his outlet is for four prongs he can, if it is for three he can't.


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RE: Tapping into 220V line

Another option. (provided the 220v line runs only from the panel and to the receptacle in question and is not split or borrowed by some other device in your house.) It will either be a 3 or 4 wire 220(probably 3) Remove the 2 pole breaker. Attach the white wire to the neutral bus, the ground should already be attached to the ground bus, and buy a new 15 or 20 amp single pole breaker for the hot wire.(go with the 15 if you are unsure)On the other side where the receptacle is, Remove the 220 and buy a standard receptacle and wire it the same as previously described.


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RE: Tapping into 220V line

That's fine if he wants to abandon the air conditioner (or finds one that runs on 120V).

But if it's a 2-wire 240V circuit, there should not be a white wire. White should never be used for anything other than the grounded conductor. Of course, he can and should remark one of the non-white, non-green, conductors if he chooses to use that for the neutral.


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RE: Tapping into 220V line

I see 12/2 used for 2-wire 240 all the time. I haven't evaluated whether it's legal but it's certainly common.

I personally run /3 cable wherever there's 240 even if I'm not using it at that time - makes changes easier later on down the road. If his last electrician was anything like me, there may very well be a white wire curled up back there with a wirenut on the end.


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RE: Tapping into 220V line

"I see 12/2 used for 2-wire 240 all the time. I haven't evaluated whether it's legal but it's certainly common."

Perfectly acceptable if the white is re-marked as hot.

"I personally run /3 cable wherever there's 240 even if I'm not using it at that time - makes changes easier later on down the road."

You are wiring for a 120/240 V load.
While it may save pulling a new line if you ever switch from 240 V equipment to 120/240 V equipment, it also costs more initially.

Few owners are willing to pay anything extra for 'future needs' that may never occur.


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RE: Tapping into 220V line

The NEC doesn't regulate what you plug into your receptacle, so maybe you could use a 240 to 120 volt transformer of sufficient capacity to operate your lamp. It would have to be rated for continuous use.

The website below offers several. (I have no interest financial or otherwise in the vendor; I just found them with a quick web search.) A couple of warnings - these transformers look pretty cheap to me for what they are, so I certainly wouldn't want to vouch for their quality; also, I see CE but not UL ratings on them.

Now if you want to operate the aircon and the light at the same time, there I don't think I can help you. I haven't seen any 240 volt "twofers" or power strips in this country. They're pretty common in countries where nominal household voltage is 240, but those wouldn't fit US receptacles. Maybe someone else knows where to find such in the US.

Here is a link that might be useful: Transformers


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RE: Tapping into 220V line

buy favorite 120v lamp. install 240v plug on lamp. solder diode in series with lamp. cover with heatshrink. enjoy lamp using 120v bulb. forget about ul requirements: this is a hack.

Here is a link that might be useful: duplex 240v receptacle


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RE: Tapping into 220V line

Smithy, uually the only posters resurrecting old threads on boards like these are spammers.

In most cases here, the original posters will read the responses until they get the answer that suits (or the one they want to read). If they don't get it within a few days, they usually vanish. Discussions that have been idle for a week or more should generally be considered stale or dead.

Dredging up old threads and responding to them, as you've been doing lately, is a waste of your time. It also clutters up the board to little practical purpose, other than perhaps telling the world more about yourself than you might want to. :)


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RE: Tapping into 220V line

I, for one, would like to state that I subscribe to the threads and get instant notification of responses, so I appreciate EVERY response I get, no matter when it is. Granted, the immediate ones are most helpful, but in some cases, maybe the first few answers are not helpful, and the project gets put aside for later. In a case like that, a late response could be very helpful. On the other hand, it's quite possible for a question or problem to "drop by the wayside" if people ignore it because of it's age.

If a person can only take time once every week or two to scan the message boards and make responses, at least he/she is trying their best to help. I don't think anybody expects 24 support on here. So thank you, Smithy!

This is just my humble opinion, and I approve this message!


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RE: Tapping into 220V line

And I, for two, would like to state that if someone is asking a basic question on here, they probably shouldn't go ahead and:

'buy favorite 120v lamp. install 240v plug on lamp. solder diode in series with lamp. cover with heatshrink. enjoy lamp using 120v bulb.'

That is terrible advice, not to mention a code violation. No one should be doing this at home.


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RE: Tapping into 220V line

I didn't say it was good advice, or that I was taking it. I merely defended his right to post it :)


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RE: Tapping into 220V line

You don't have the right to shout FIRE in a crowded theater.

This is more or less the same thing. Advice like this can be dangerous to someone who didn't know what they were doing, and didn't know any better


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RE: Tapping into 220V line

I have seen factory- made lamps with a diode in the switch to convert 120v ac into 60v dc. i also mentioned this was non ul compliant, just that it will work. i also meant to solder it in.


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RE: Tapping into 220V line

If you are asking can you tap a 3 wire 240 volt connection for 120V. Sure. The 240V is relative to the two hot wires as they are out of phase with each other. Each hot wire is only 110V relative to the neutral wire. The lamp will work connected to one of the hots and the neutral.

Should you do this? That is a different question. It's not my place to advise that since you didn't ask, but technically it will work for a lamp assuming you are in North America.

You could consider getting a light bulb from Europe.


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RE: Tapping into 220V line

What will work Benrise? There's no neutral to connect to here. There's no legal way for him to connect a 120V item to the 240V circuit he has here.


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RE: Tapping into 220V line

a diode in series with the lamp will give you 120v dc, but it is not legal.


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RE: Tapping into 220V line

I expect a dimmer would be legal.


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RE: Tapping into 220V line

... a diode in series with the lamp will give 240V DC pulses with a 50% duty cycle.

I'm too tired to sit up much longer and prove this mathematically, and it MAY be flawed, but my thought is that a 100W bulb given 240V through a diode will actually receive 400W during the ON time (Twice the voltage, same resistance, is twice the current. Since we've doubled both the voltage and the current, the power is quadrupled -- if E*I=P then 2E*2I = 2*2*E*I = 4*E*I = 4P.)

Four times the power, 50% of the time, is an average of two times the power.

Your 100W bulb will be getting 200W, which, as far as its filament temperature is concerned, means it is effectively "seeing" about 170V. This is obviously better than giving it 240 direct, but is not the same as actually converting the 240 to 120. You will replace lamps frequently.


Put another way, the diode proposal halves the power, not the voltage. Since the power is 4x what the lamp wants, halving it gives us 2x the lamp rating.


A local discount store had recently an entire rack full of 240V light bulbs with standard bases. I might suggest these as a MUCH better option.


Please do not suggest using a 120V dimmer on a 240V circuit.


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RE: Tapping into 220V line

Pharkus, that looks right to me. IIRC the rule of thumb is that a diode in series with a light bulb reduces the effective voltage about 30%.

The only ways I can see to do this reliably and safely are a 240 volt lamp (a specialty item here, though available off the shelf in Europe and some parts of Asia), or a transformer.


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RE: Tapping into 220V line

NEC Article 210.6 (A) (1) specifically prohibits luminaires (lighting) operating on a voltage of more than 120 volts between conductors in dwelling units...........


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RE: Tapping into 220V line

what about a step down transformer?


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RE: Tapping into 220V line

Abnorn, keep reading that article. It absolutely does not say that.


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RE: Tapping into 220V line

The open-circuit voltage on instant-start fluorescent lamps is significantly higher than 120V! I guess I'd best stop installing them in dwelling units.

I have the NEC here, but not at my fingertips. I do not recall it saying that. I do recall something regarding a limitation for medium-screw-base lamps, however... which would make the 240V units I found at Marden's illegal, but that doesn't stop them from existing!


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RE: Tapping into 220V line

Petey......I read the NEC article and Charlie's Rule.....My post was a sound byte reply aimed at the previous posted suggestions.......

Would YOU allow the Pharkus' lamp or any of the other suggestions in the OP's specific case ????????

Charlie’s Rule of Technical Reading

It doesn’t say what you think it says, nor what you remember it to have said, nor what you were told that it says, and certainly not what you want it to say, and if by chance you are its author, it doesn’t say what you intended it to say. Then what does it say? It says what it says. So if you want to know what it says, stop trying to remember what it says, and don’t ask anyone else. Go back and read it, and pay attention as though you were reading it for the first time.

Copyright © 2005, Charles E. Beck, P.E., Seattle, WA


""210.6 Branch-Circuit Voltage Limitations. The nominal
voltage of branch circuits shall not exceed the values permitted
by 210.6(A) through (E).

(A) Occupancy Limitation. In dwelling units and guest
rooms or guest suites of hotels, motels, and similar occupancies,
the voltage shall not exceed 120 volts, nominal,
between conductors that supply the terminals of the
following:

(1) Luminaires
(2) Cord-and-plug-connected loads 1440 volt-amperes,
nominal, or less or less than 1⁄4 hp

(B) 120 Volts Between Conductors. Circuits not exceeding
120 volts, nominal, between conductors shall be permitted
to supply the following:

(1) The terminals of lampholders applied within their voltage
ratings
(2) Auxiliary equipment of electric-discharge lamps
(3) Cord-and-plug-connected or permanently connected
utilization equipment
(C)
(D)
(E)..........""

Pharkus....I see those lamps used where the Pumphouse/outbuilding is feed with only 240 V...........

Here is a link that might be useful: Charlie’s Rule of Technical Reading


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RE: Tapping into 220V line

Funny thing about the NEC, you have to read and understand the entire section.

"...between conductors that supply the terminals of the
following:"

This does not place any limit on the internal operating voltages of luminaires, just the branch circuit voltage feeding them.

Many discharge lamps have very high striking voltages, but this voltage is not on the supply terminals of the device fed by a branch circuit.


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RE: Tapping into 220V line

I will say again: the NEC does not restrict what a homeownwer plugs into an existing receptacle. There is no reason the OP can't plug in a "voltage changer" (autotransformer type), usually offered for user overseas where household voltage is often 240v, and then plug his lamp into the transformer.

He just needs to be sure the transformer is sized for the load and its duration of operation (don't buy in intermittently rated transformer for a lamp that will be operated for hours at a stretch).


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