DIYbanter - View Single Post

Doug Miller

In article . com, wrote:
Thanks for all your help!

When I get home tonight I'll check the voltage accross for 240v. I
didn't do that. At the main panel I connected the black and red to the
2 pole breaker, ground to ground bus, and white to the neutral bus (not
used). I'm thinking I'll find that I don't have 220v. The sub-panel
is not bonded.

By which you mean, I hope, that the ground and neutral busses in the subpanel
are not bonded to each other. It's *supposed* to be that way. The *only* place
where they are ever bonded together is in the service entrance panel.

Could that have anything to do with it?

No. The neutral isn't used at all in a pure 240V circuit (and can be omitted
altogether), and the ground isn't used except in the case of a ground fault in
the equipment (i.e. in normal operation, the ground isn't used either). So
nothing involving either the ground or the neutral would have any effect on
the problem you're seeing.

How will I
know where in the panel I can add 220v breakers and where I can't?

In *most* panels, any place that you can put a double-pole breaker will give
you 240V. Your panel may be an exception, as at least a couple of us have
noted, and the easiest way to tell where you can and can't is to look at the
label on the inside of the panel cover -- that will show the possible
configurations. Another way to tell is to probe between the lug screws on
adjacent breakers (with the breakers on) to see where you measure 240V and
where you get only 120V. Yet another way is to pull the breakers, and look at
the configuration of the bus bars.

But before you do any of that, the *first* thing you should do, in my opinion,
is to measure the voltage between the two main breakers (or lugs) in the
subpanel, and see whether you get 240V or 0V. I think you'll see 0V, because
- assuming that you've described everything accurately - the simplest
explanation for the problem you're seeing is that the subpanel is not wired
correctly at the main. Specifically, I think that if you look in the main
panel at the wires feeding the subpanel, you'll find that when the subpanel
was installed, the black and red wires feeding it were connected to two
separate single-pole breakers (instead of to one double-pole breaker), and
those two breakers are on the same leg of the service.

I used the 10/3 so that I can change the configuration should my needs
change in the future.

That's fine -- just wasn't necessary for *this* application. But planning for
the future is always good. :-)

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.