ECN Forum Forums General Topics of the Trade General Discussion Area Microwave blows up

Would a GFI receptacle care if it were wired on a multi-wire branch circuit...or a better question is would in trip when the shared neutral read an imbalance?

And another question: "is it darkest just before it turns completely black?"

No and no

Roger

It would be darkest when it turned completely black.

Roger

Roger...good answers and both correct. How about trying to protect downstream of a GFI receptacle when installed into a multi-wire circuit? Wouldn't the GFI trip when wired in this location?

Devices fed downstream from a GFCI receptacle would not change it.

Now on the other hand, a MWBC fed from two single pole GFCI breakers would cause tripping from unbalanced current, but we would need to recognize this would not be due to fault currents.

Roger

The GFCI Can be sourced from a shared neutral but you wouldn't be able to share the neutral downstream.
Joe

Here we go.
I was for some years, an Appliance Serviceman, repairing things like M/Wave ovens.
This was a required part of my Electricians Apprenticeship.
Now,
A microwave oven uses a high current and frequency to cook food.
It uses 2.4Ghz as a standard frequency.
The biggest thing to look out for in a microwave oven is not the Magnetron, but the Capacitor that drives the HV side of the magnetron.
Only 2uF, but these capacitors can store up to 1500V, I am not making this up.
If one of these capacitors becomes a dead short, it can have real ramifications for the connected supply.
Not only will it blow a fuse, but it will make a nasty mess of molten copper.
That is why M/Wave ovens are required to be protected by ceramic fuses, not glass type fuses.

To do so would be a violation......even if it would work (which it wouldn't).

"300.13(B) Device Removal
In multiwire branch circuits, the continuity of a grounded conductor shall not depend on device connections such as lampholders, receptacles, and so forth, where the removal of such devices would interrupt the continuity."

A pretty common failure becomes a nightmare on a MWBC when the neutral isn't pigtailed. A (often backstab) receptacle removes itself from the circuit, opening the grounded conductor.

As always, improper installation is the culprit.



[This message has been edited by electure (edited 01-05-2007).]

HLC, I think I misunderstood your last post. If a single neutral is used downstream of the GFCI recptacles then I agree with Joe and Electure.

Roger

Is this in a house?.
You guys should be ashamed of yourselves.
Shared Neutrals in a house?.
Get Real!.