I recently move to a new home. One plug in the garage wasn't wired with an
outlet yet. It appeared on the panel as "Heater" and has two breakers. I
think it's what they call a 208 volt heater plug (why 208?) Are these
common? Can I use it as a 220 instead (Table Saw)? There doesn't appear to
be a neutral only two hots. I'm guessing 12 gauge wire. Thx.
I'm surprised that there would be a 208 volt service in a residential area.
The utility that serves your area would provide 220v and half of that is the
110v that is standard in the US. For you to have anything different would
require a step-up or step-down transformer (in your case) somewhere in the
circuit. Check around your circuit breaker panel for a transformer on the
wires that run to the plug you mentioned. If there isn't any transformer
than you probably don't have 208v. However, you may want an electrician
check it out. Circuit breakers won't step-down the voltage. Hope this
208 is anything but a generic name.
And it is entirely possible that some newer residential
environments (especially multifamily homes) will have 208
service (which is _NOT_ the same as 220).
Don't post if you don't know.
Because you don't need one. 220V is two 110 legs....180 degrees out of
phase. If you measured the voltage between either leg and neutral it would
be 110V, but between both hot legs, it is 220V. Some appliances (like a
dryer) require a neutral because some functions of the appliance (like the
light) run on 110V. On the inside, a dryer is really a hybrid device.
Basic motors and heater are not hybrids; they don't need 110, therefore do
not need a neutral.
Table saw don't ordinarily need a neutral, though the magnetic switch on
mine does.(don't ask...)
Two 120v wires can mean either 240v or 208v.
It would be very unusual to have 208v in a home, so it is probably 240v and
is probably okay; but if it really is 208v you could burn the motor out.
It is prudent to test it with a voltmeter and/or check with your utility to
It will need a neutral if it also has a 110V device (such as a light bulb,
Also I read somewhere that some new regs require 4-conductor wiring for all
220V outlets. However, I do not have a reliable source for that statement
(nor do I know if it applied to just outlets or devices as well), take it
as a rumor I suppose.
You only need 4 wires (3 conductors and a ground) if you have something that
actually needs the neutral; such as a table saw with a 120v light bulb (?).
Otherwise you only need 3 wires.
My dryer puts 7a into the ground (technically an "uninsulated neutral")
which is a little spooky, but I have never heard of anyone having a problem;
which could result if the neutral connection broke somehow and energized the
Do you mean the safety 'green' wire? That's highly dangerous as well as illegal...
could put power anywhere because of
the water pipe grounding. There was a case here of some ones house going on fire
because of excess ground current in a
neighbors house!! For some reason, probably linked to the electric company location
of their ground, the current found
its best path thru the ground leads of the next house, and the attic caught on fire
where the leads entered the house.
I talked to a company engineer, and he said they detected 70 amperes of 'lost' ground
current in one of their feeds!!
You should re-wire it with the proper 4 wire connector...
It all depends on the AHJ. 220 V receps inside house need a neutral, 220
outside such as in a garage don't need neutral per the building inspector
here in Phoenix and that only covers new installations. Existing 220V still
only requires 2 hot and a ground.
That is not adequate; 208a will test about 115v to ground on each also. You
have to test hot to hot.
208v has two 120v hots 120 degrees out of phase. Between them they are
240v has two 120v hots 180 degrees out of phase. Between them they are
240v. (strictly speaking they are not out of phase, but it is close enough
to the truth for this purpose.)
If I'm not mistaken you can't have true 208 without 3 phase power, i.e 3
hots coming into your house. Most US residences will have 2 hots which is
correctly referred to as single phase 220 service. This is what you've got.
probably a heater or a dryer.
Any electricians confirm this?
You can have true 208V single phase without 3 phase power being supplied.
Line-to-Line is 208 V and Line to Neutral is 120 V.
However, in my experience, it is highly unusual to have 3 phase power
supplied to a residence. The most common US residential service is 120/240.
Does it matter that the breakers are both on the left hand side of the
panel? Not one on the left and one on the right? Does that mean both lines
are coming in to the plug on the same phase? And not 180 degrees out?
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