Re: Dryer connection (was Re: Air conditioner problem)

Top posted on purpose
Elliot,

Now that you specified 10-30 as opposed to 6-30 I understand the confusion.

The 10-30 set has been obsoleted at least a decade. This does not mean you will not find them in use, you just will play hell buying a replacement.
Many community codes have required a separate machine ground if power was provided by a 10-30.

As to your box, it's anybodies guess who wired it and when. In years of digging around in this stuff I have found (and often corrected) some really strange things that were done by card carrying electricians and inspected by the local inspector and signed off.

Actually, in the two electric dryers I have owned, the 220 ran both the heater and the motor, but the timer and the drum light (if equipped) ran to the ground (specified as ground in the equipment manual in one of them).

Just watch out for ungrounded equipment, but it sounds like you do.

I like solid grounds - Too.

Matt Colie


Elliot Richmond wrote:
On Mon, 21 Jul 2008 08:31:30 -0400, Matt Colie <matt.colie@xxxxxxxxx>
wrote:

Well, there seems to be a lot of confusion about this issue. I think
the confusion arises partly because in US wiring, the neutral leg of
the supply is physically grounded at the house. Also, we may talking
about different NEMA standards (see below).

Here is a do-it-yourself web site that has somewhat contradictory
answers. One claims the "L" shaped terminal is a ground, the other
asserts it is a neutral.

http://www.findhomeanswers.com/do-it-yourself/1619-2-Do-It-Yourself.html

Here is what I know: In the unused dryer plug in my house, there are
three wires coming straight from the breaker box which is only a yard
away. They appear to be in conduit. There is a red wire, a black wire,
and a white wire. There is no green or bare wire. The red and black
wires are connected to the slanted terminals (as they should be) while
the white (according to code, this would be neutral) is connected to
the "L" shaped terminal. This terminal will show continuity to ground,
because the neutral leg is grounded.

I don't have an electric dryer to examine, but it is my understanding
that the only thing in the dryer that requires 220 V is the heating
element. The rest of the bits, such as lights, timers, etc. use 110 V.
I do not think an appliance would be set up to use the ground (always
a green or bare wire) as the return leg for a 110 V bit. They would
use the neutral leg for that.

By the way, Matt, the plug I am talking about is a 10-30, not a 6-30.
I think the 6-30 plugs are grounded.

Here is a diagram of the NEMA 10-30 standard (see the drawings, not
the plugs which are wrong).

http://www.stayonline.com/detail.aspx?ID=6340

And here is a collection of NEMA 6-30 compliant plugs.

http://www.levitonproducts.com/catalog/dept_id_972.htm

Now, for those of you that are concerned that I may electrocute
myself, thanks for the concern. I could perhaps sell tickets to the
event and my life insurance is all paid up. But, with the rig I
envision, I will have a separate ground circuit from the camper cord,
through the box, into the ground terminal on a standard plug. GFCI
considerations aside, I do want a robust, separate ground circuit to
my trailer frame.


Elliot Richmond
Itinerant astronomy teacher
.

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