Is it possible, and safe, to run a 110 outlet off a 220 outlet? The
electrician said it was, but out of code, so he would not. BUT I know
one of the mag's had an article last year which showed how.
I am not an electrician, so please be as clear as possible..thanks..
If you have a 15 or 20 amp dedicated outlet for something like an
airconditioner, it can be converted at the breaker panel from 240 to 120
volt, but if you're looking to tap 120 volts from an existing 240 volt
outlet, it would need a neutral conductor, which many 240 volt outlets won't
How many amps is the circuit?
How many wires is the circuit?
Assuming you want to install a 120v 20a (or 15a) outlet, the 240v circuit
cannont be over 20a (or 15a).
And it will have to be 3wire so you have a neutral for your 120v outlet; and
that would be odd to find on a 20a 240v circuit.
So, you probably have too much amperage, or not enough wires; so you
probably can't do it.
The electrician might have been thinking of using the ground wire as a
neutral. That is certainly against code, and while it would work, isn't
something you want to do. I hope a magazine didn't recommend it.
How can he have too much amperage available? If the wires two the 120
volt circuit are as big as the wires to the original circuit, and the
receptacle is big enough to handle whatever is plugged in, how can
there be too much amperage?
The rest I agree with.
It's real simple: the electrical code requires that the receptacle's amperage
rating cannot be less than that of the circuit. The only exceptions are that
15A receptacles are permitted on 20A circuits, and receptacles rated less than
15A are permitted on 15A circuits.
Doug Miller (alphageek at milmac dot com)
The basic problem is that the breaker provides some protection to the
receptacle, as well as the wiring. If you try to draw 30 A from a 15 A
receptacle on a 15 A circuit, you'll trip the breaker. If you connect a
15 A receptacle to a circuit wired and fused for 30 A, you can draw 30 A
continuously, and that's safe for the wire but the receptacle may
The breaker *also* provides some protection for the wires in the power
cord of the device plugged into the receptacle, until you get downstream
of the fuse in the device (if any). A short caused by frayed insulation
in the power cord will have to trip the branch circuit breaker. (This
isn't true in the UK, where individual plugs have fuses sized to protect
the cord and/or device).
Ignoring code, if it is a 4 wire 220V outlet with 2 hots, a neutral
and a ground, an adapter that connected to one of the hots, the neutral
and the ground would be safe. OTOH, if it is a 3 wire 220V outlet, with
2 hots and a ground only, then there is no neutral to connect to. It
would be possible to get 120 by connecting to one hot and the ground
in this case, and in fact for small loads like lights or controls on
220v appliances, this used to be common practice. Personally, I might use
such an arrangement for a temporary, one-time job, perhaps connecting
a light or small powertool if there was no other outlet within
convenient distance, but not for a permanent outlet.
When the game is over, the pawn and the king are returned to the same box.
Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf.lonestar.org
On Feb 10, 1:00 am, email@example.comNoOnSePsAtMar.org (Larry) wrote:
In one of my previous homes built in 1980, a three wire 50A range
outlet was still code. It was also common for ranges widely available
at the time to include a 120V convenience outlet (usually controlled
by the broken clock). I'm assuming that such configurations are
grandfathered into the more recent code, suggesting that safety is not
a major issue (otherwise, rewiring would have been mandated along with
subsidies for those unable to pay for such a change). I see that
newer ranges provide a jumper between neutral and ground to
accommodate three wire installations. What is the real downside to
such a configuration? Why was the code tightened up?
The code prohibits using a ground as a neutral and vice versa (this
being a grandfather exception, one of very few). If the neutral-ground
opened, the frame of the range would be hot. With separate neutral and
ground that would take 2 failures.
My favorite response is from gfretwell:
"The stove end was wired like they did in the WWII days when copper was
in short supply and we used a 3 wire cable. NFPA finally figured out the
war was over in 1999 (96?) and changed the code, requiring a 4 wire
circuit and plug."
That's the whole point of asking a question in a newsgroup. Unlike
many of the pros here, most of weren't born with this knowledge. The
only way to gain this knowledge is through research. The newsgroups
seem to be a good source for useful information from those who have
already acquired this knowledge and are willing to share it. It's
also a good source for a list of gotchas from those who have already
made mistakes. This is, essentially, a DIY newsgroup. As such,
there are people here who are determined to do it themselves. Far
better that they embark on their adventure with an idea of what
they're doing rather than totally blind. If "Don't do it yourself!"
was a universally acceptable answer, I could just ask my Mom.
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