in my home are a few 240v outlets that used to serve air conditioners.
We now have a central air system, so those outlets are no longer
Can i leave the 240v outlets as is and plug any old device into them?
For instance, if i were to plug my alarm clock into that outlet, what
How can iconvert them to 120v outlets? is it simply a matter of using
only one of the two hot wires to wire a new 15 or 20 am outlet?
I don't know yet as i haven't opened them up. Assuming there is, i can
simply arbitrarily select one hot and the neutral wire those two to the
new 120v outlet, correct?
Going back to my other question, what if i plugged an alarm clock into
that 240v outlet as it is today, would that do any harm?
If you're changing to 120V, you can repurpose the other hot as your
neutral (suitably marked of course). Indeed if this is a single run that
served a window A/C it's probably 12/2 w/ ground with the white wire
tagged black or red with tape.
Years ago I plugged my electric razor into a 240v outlet in Israel. It
immediately went up in a puff of blue smoke. I expect your clock would meet
a similar fate.
Does the outlet have 3 holes or 4? If 3 (which is almost certain to be the
case) you have no neutral and cannot use it for anything but devices that
need pure 240v. If 4, you could use it as the basis for a multiwire
BUT, if 3 you can pull replace the 240 breaker with a 120v breaker; and put
the left over hot (hopefully a white wire) into the neutral bus. You will
now have, as soon as you replace the outlet with a 120v outlet, a 120v
Obviously you have to be certain that you replace all the 240 components
with their 120v counterpart, and that you get everything sized properly, but
it is not difficult.
Check the AC input to the alarm clock. If it can accept 100V - 240V
be ok. If not you will probably damage it with 220V.
Home Improvement Forum
cannot be done safely. breaker and wire and outlet must all match.
alarm clock would normally trip a 15 amp breaker. but even with an
adapter, improperly feeding large available amperage into a low wattage
device is tempting a fire when the alarm clock fails.
I do my own electrical work except for three-phase (240v).
Within the last two years, I knew the line going to my dryer
was problematic. It was just a matter of replacing the line
from the box to the outlet - less than 40 feet. I paid
someone to do it. That's how afraid I am about three-phase.
Electricity kills people and burns down houses. If you do
not respect it, you could die from either the shock or
Well, the wire can be heavier than it needs to be. And the wire and
breaker can both be heavier than the outlet will allow to be plugged
After all we plug an 11 amp Hoover vacuum cleaner into the same
Huh? I don't think he will know that you're kidding.
If 20 amps will start a fire, 15 amps can probably do so too.
After all we plug an 11 amp Hoover vacuum cleaner into the same outlet
we plug a 1/10 of an amp radio. And that could be a 15 amp outlet or
a 20 amp outlet. Any of those appliances could some day have a
*If* you can get the plug into the receptacle -- which is doubtful, since the
prong configurations are complete different -- the result would be a loud
"POP" accompanied by a bad smell, smoke, and possibly flame.
Oh -- the alarm clock won't work any more, either.
Call an electrician. Please. You don't even begin to realize the danger you
could be creating. At a bare minimum, at least go to a library or a home
center (like Home Depot or Lowes) and get yourself a book on residential
electrical wiring. Electricity is dangerous to those who don't understand it,
and (no offense intended) your questions show that you're in that group.
Doug Miller (alphageek at milmac dot com)
You can not plug a 120v plug into a 240v receptacle unless you
physically take a pair of pliers or something and bend.
If there is a neutral there you can change the receptacle out to a
120v receptacle but would also need to change the breaker to a single
pole breaker. Just have to figure out which hot to use.
You sure about that?
My reading of tables 210.21(B)(2), 210.21(B)(3) and 210.24 is that when
using a given receptacle, there are limits as to the breaker amperage,
regardless of wire size.
For instance, you cannot put a 15A receptacle on a 30A or higher
circuit, and you can only put one on a 20A circuit if it is a duplex
receptacle or there are other receptacles on the same circuit.
Motors and arc welders are excepted from the above, but that's a whole
That doesn't have anything at all to do with voltage, though -- and you
appeared to be saying that changing from 240V to 120V would require changing
the breaker to a different amperage as well, which is not the case.
Right, but that's not the same issue. I think we're talking about two
Doug Miller (alphageek at milmac dot com)
Sorry, my bad. I had assumed that the original circuits were
heavier-duty than 20A.
Assuming that the original circuits are 15A circuits, or 20A circuits
wired with #12, then there would be no need to change out the breaker.
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