I have a 30 Amp, 220 volt recepticle to power a shop heater (which
lists these requirments). Ive purchased 10-3 wire for this (though im
thinking 10-2 would be sufficient as well).
The 30 recepticle I bought has 3 poles on it to hook up the wire (2
hot, and one green - neutral).
When I wire to my 30 amp breaker, I have 2 hots coming out of the
breaker which would go to the 2 hots on the recipticle.
I'll run the ground from the breaker box to the green ground on the
What Im confused about:
With 110 15 amp I run one hot from the breaker, one neutral (white) and
one ground (copper).
But where does the white go when im hooking up the 220? Theres nothing
for it on the recepticle, so I guess it isnt used?
Any help or explanations would be appreciated!
You only needed 10-2 cable.
Connect the black and red wires to the breaker and the green wire to
ground. You have 2 choices with the white wire, and I'm not sure which
is better (I don't think it really matters): In the receptacle box, tape
or wirenut the end of the white wire and don't connect to anything. In
the breaker box you'll either connect the white wire to the neutral buss
or leave it unconnected and tape/wirenut the end. Don't cut the white
wire short at either end, you may need it someday if you ever need to
hook up a 240/120 device, like an electric clothes dryer w/ a 4 prong
You are correct, if it is a straight 30 amp 240 volt outlet, you only need
the three conductors. If you used 10/2, you would connect the white and
black to your breaker and the ground to ground buss. In your case you don't
use the white/neutral as you don't have one on the receptacle. Some devices
require both a ground and neutral, in which case you'd have a four wire
Thanks - This is exactly what I did.
10-2, color taped the white lead at both ends to indicate its hot.
Checking the coltage indicates to me ive done things correct - each hot
to ground reads 110v giving me 220, correct?
Each hot to ground should read 120v. If it actually reads 110v you have a
problem of some sort. Did you test hot-hot? It will be 240v if you did it
right, and 0v if you did it wrong. Yeh, its tough to do it wrong, but
stranger things have happened.
I would have used 10/3. You don't need the neutral now, but it is very
possible that in a couple years you will need a 240v circuit with a neutral
and will regret saving the $1.50.
Sorry, yes it reads 120v.
No, I didnt test the hot to hot, but thats good to know - ill confirm
Out of interest, what would be the cause/reason of hot to hot reading 0
volts? It seems like if each hot to ground reads 120, then the hot to
hot would *have* to be 240?
As for 10/2 vs 10/3 - what youre saying makes sense. However this
outlet im mounting 3 feet from the fuse box for heat while I drywall.
Ill need to decide where I want to permenatly put the switches, in
whcih case ill do it with 10-3.
Thanks for the help.
You would really have to screw up to do this, but if you took both hots from
the same leg of the box, then they would be zero between them; and you would
get no heat.
I found someone had done that on a multiwire circuit in my house; luckily
they were lightly used circuits or they could have started a fire easily
I had to do something similar to this a year or so ago, I ran 10-3 for the
exact reason you listed. Boy am I glad, saved me some time down the road
not having to rip/replace, just take the wire nuts off the unterm'd neutral
What if a neutral is needed? Is it permissible to have the third pin be
neutral (as was done for many years HOT-HOT-NEUTRAL no ground) or does the
Code now require 4 pin receptacles? Neutral is needed on equipment where
some components are 120V.
The standard 240V/30A clothes dryer outlet had three pins using a neutral,
and yep, the frame was "grounded" with the neutral. Seems astonishing but
that's how they were and in many cases still are.
The OP appears to be putting in a construction cube heater. That's a pure
240V load (two hots plus ground). Neutral is not required, and should not be
Since he's already bought 10/3 wire, he should wirenut both ends of the white
without connecting them to anything.
But they're not allowed to be done that way anymore.
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
This is your idea of doing good work?
The NEC expressly prohibits paralleling conductors below 1/0.
The neutral and grounded conductor(s) can only be connected together at the
service. Any other intentional connection is a ground loop and ooops
expressly prohibited by the NEC.
Me hopes your being sarcastic
I dunno where this post came from... maybe I've lost track.
I'll say this ONE MORE TIME for all that can read: DO NOT.. EVER...
GROUND a NEUTRAL ANYWHERE but at the panel where power comes into the
building (called a service entrance). Anything else can get you
electrocuted. Elsewhere, grounds go with grounds, neutrals with
neutrals, hots with hots.
To the OP.... if your heater is 240 volts and does NOT require a
neutral, then your receptacle (notice spelling) needs two hots and a
ground, wired to a appropriately sized two pole breaker. If you don't
know what this means, you need to hire a electrician.
the OP has a 230 volt heater. Two wires black and red for power. And no
Thanks for the very wise counsell about grounding a neutral. I'll
remember that if I'm ever working with a current carrying neutral.
Actually, I did take a rap off a neutral once. I'll tell you about it,
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