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

Peter,
I'd also say to start at the receptacle. Look for an open neutral and also check to make sure the polarity is correct.

About 4 years ago, I plugged in a brand new Bosch raised-vent exhaust and saw that same flash. Turns out the factory pinched a hot wire between two metal frame parts and when I plugged it in I got a flash and the breaker tripped.

Nothing a pair of pliers can't fix...

Ian (Pulling a permit to rewire a Levittown House! <not> ) A.

I agree with you on the multi wire branch circuit. If done correctly the have there merit. I pesonally limit my use of them in my are. As so many here do not understand them. I have seen many burned nutreals due to have both circiuts on the same phase. I once had a whole loadcenter done with multi wires and all were on the same phase. All blacks on 1 side all reds on the other opposite each but on the same phase. Looked good thou.


Ob(Phil)

Who knows this could be endemic all over the hose and the guy just thinks its normal to have some lights get brighter and some get dimmer every time he turned the old on on.

Had one like that last week. POCO neutral had obviously been on the way out, or been loose for some time from what I could tell be a breif interview of the guy. Lights had been doing the hokey pokey since he bought the house last year... (Home Inspectors said it was normal.... - I did a little experiment with dimming/raising some as an example - far from normal!) Anyway the guy gets a new plasma, and DVD - and a new dryer for himself for X-mas. He tells me as he is taking a break in his first movie on the thing, he throws some clothes in the new dryer - comes back out and the DVD and plasma are on fire.... He calls the cable company to complain.... They tell him to call an Electrician - he calls us - we tell him to shut off the main and we'll be there shortly - he calls back after fifteen minutes to cancel saying his neighbor has the same problem.... The guy turns his main back on to find out how to contact Comcast - blows up his computer.... (This is after warning the guy to keep the power off - numb-nuts still thinks it has to do with his cable line, as his neighbors TV also caught fire.) Smarter neighbor calls PG&E - they get there and fix the lost neutral - and find that his hacked together main panel has no bond - tell him to call an electrician - he calls back, and I go out there to find all 2-wire circuits - including the gas dryer - Carpenters doing foundation work had moved the water bond to a painted portion of pipe - no rods - but there was a bond at the main.... Turns out PG&E is buying TV's and other crap for most of the block.

I totally agree. But the consequences of an open neutral on a two wire circuit are usually that it simply stops working, right? No harm to the connected loads, usually. Now what happens when you open the neutral on a MWBC? Or for that matter, the service?


For branch circuits, absoultely. I have no MWBC's and any place I live in won't. But the service is a factor not in my control, and:


What you all have lost sight of, and if you've read my other posts on this topic carefully, I have no issues whatsoever with service conductors and connections being set up as multiwire.

For cryin out loud, even I know that the laws of electricity make the single neutral concept a "fact of life."

Where I take issue and frankly am a bit offended is when:


..since in those other discussions I have readily conceded that in other lines of work and installations, MWBC's are not necessarily a bad thing and can indeed offer benefits.

But to make such proclamations when one has not had the same experiences and deal with the type of equipment I have for the last 20 years is downright rude. I would not presume to tell anyone here that how they wire High-bay lighting, process MCC's or a factory for that matter (all types of installations where I have no experience) is "unsupported" and "anecdotal."

Again, if one cares to carefully review the topics where we have had this discussion before, the main things I need to make clear here are:

One, my position is based on the use of MW branch circuits only in my line of work;

Two, any details I have related are NOT unsupported or anecdotal, thay are the facts in the situations I have encountered;

Three, I have in the past and again reiterate that since each of us works in different areas of electrical installations, that what works (or doesn't) for me will or won't work for others.



It's not a matter of scared, it's a matter of providing the best possible performance to my clients. And if it works for others, so be it. I have no arguement with it.


Nope, have to disagree here. Out of all the cases (50+ and counting) I've dealt with, only two were workmanship issues. One was a poorly made connection, another was overloading due to sloppy phase placement.


LK, well said.

Obsaleet also made good points.

We all have our hot button issues, and I think we all know what mine is.

Tony IMO you are mistaken, your equipment can not tell the difference between a properly wired two wire circuit and a properly wired multi-wire.

It is impossible.

Draw the circuits, from source to load and figure out how it can possibly make a difference.

You have put blinders on.

But to each their own, some people also believe in ghosts.

Bob

[This message has been edited by iwire (edited 01-04-2007).]

Mean to tell me you don't?????? Believe in ghosts....

I believe in only what can be explained with facts.

Of course that whole 'how did we get here' question is a tough one.

Where does (outer) space end? And whats after that? How infinate is infinate? Questions that have boggled me since I have been able to think. Also being fact based - but not without opinion - ghosts are hard to believe.

I agree with Bob, the loads wouldn't care how the power is delivered, two wire or MWBC, as a matter of fact the neutral conductor in a MWBC would even be cooler in operation if both circuits are being used (bar any additive harmonics)

Roger




[This message has been edited by Roger (edited 01-04-2007).]