Replies

1. 
   pyroman | Apr 26, 2005 06:37am | #1

   Holy cow... I don't have an answer or idea for you, but I can't wait to see what the others may say, this sounds like something of quite a unique problem.

2. 
   4Lorn1 | Apr 26, 2005 06:53am | #2

   Can you expand on your statement: " I found a number of breakers that shorted to their respetive neutrals."

   How are you reading the voltages and continuity? Digital meters, high impedance, can lie to you.

   Re: "If I turn the breaker on I get 120 on the neutral and 240 it I go to the opposite bar. Please help."

   Sounds to me like your reading across light bulbs and motors with he switch on and transformers. This case, of course, would read 120v to ground and 240v to the opposite bus bar with the breaker on.

   Sounds like your in over your head and need an electrician. Experience counts. Of course you likely drill your own teeth and removed your own appendix with nothing but a can opener and a bottle of generic vodka.

1. 
   junkhound | Apr 26, 2005 07:01am | #5

    

   4Lorn:  Went to check my own reply and saw you beat me to some of the same responses!

   This is one time I have to agree the guy needs some professional on site assessments vs. DIY.

   Edit to ryguy - if even this total DIY  thinks you likely need pro advice (it is one of the very few times i've ever said it, if not the first) then you either need to send a picture or study more first.

   Edited 4/26/2005 12:18 am ET by JUNKHOUND

3. 
   junkhound | Apr 26, 2005 06:58am | #3

   Well OK, see this is your first post (after reading the post, first thing I checked)

   So, welcome to breaktime.

   re:

   a number of breakers that shorted to their respetive neutrals

   OK, so this is either a put up post for jokes or you have a real problem with terminology. Have only seen what is described per my terminology after a very large (100 kA or more) lightning strike or massive EMP test at a military missile silo. 

   We need clearer terminology, etc.  There is a lot in the original post DOES NOT COMPUTE! Maybe your mean "shorted" as measured with a high impedance meter and the ground screw (or other screw) loose. Please clarify, etc..........

4. 
   CPopejoy | Apr 26, 2005 06:59am | #4

   Hire a pro to evaluate (and probably replace) the panel.

   Based on the description you gave, I think you're not qualified to decide whether the panel is salvageable or not.  What exactly do you mean by "breakers that shorted to their respetive neutrals"?

   Bad idea to disconnect the neutrals and re-enegize the panel.  If any of those circuits is a multi-wire (Edison) circuit, you may have just fried appliances on the circuit.

   Bad idea to re-energize the panel before using a megger to test the insulation standoffs holding the hot buses and all the wires in the panel, to make sure that there's not so much soot and other residue on the surfaces that will give rise to a phase to phase short or a ground fault.

   There's a lot of energy in a panel and it's unforgiving.  My feeling is that a little info from a bulliten board won't make you qualified to make the judgement calls concerning, or deal with the hazards of, working around 240 volts and 100 amps or more.

   Cliff

5. 
   BillHartmann | Apr 26, 2005 07:06pm | #6

   " I have continuity between my hot and its matching common when the power is out."

   Do you mean that with the hot and neutral disconnected at the panel and then you test between hot and the neutral and continuity?

   If so that means that there is some kind of "load" on that circuit. It could be ceiling light that is one, a wall wart transformer, an apliance that is on. Might even be something has small as a night light or clock.

   "If I energize the circuit I get 110 thru the hot and 110 thru the neutral. "

   If you have 110 that is too low. 120 is the nominal voltage.

   Do you mean that you connect the hot to the breaker and leave the neutral disconnected then you measure 120 voltage from the disconnected neutral to the neutral bus bar?

   If that is what you mean then that is normal IF YOU HAVE A LOAD ON THE CIRCUIT THAT YOU IMPLIED ABOVE.

   Even if there is no load on the circuit and you don't understand the type of equipment that you are using to measure the voltage with it can give you misleading results.

   "I have no continuity between the disconnected neutral and the bus bar yet the neutral will still complete the circuit."

   How is the circuit "complete". Do lights on that circuit with the disconnected neutral work? If not the circuit is not complete.

6. 
   DanH | Apr 26, 2005 08:19pm | #7

   First off, remove all breakers and check the bus bars behind them for damage. If the bar is scortched in one breaker position, don't use that position in the future. If several positions are scortched, you need to replace the panel. Also check the bus bar insulators to make sure they're OK and not sooted up. It wouldn't hurt to do a final check with a meter, as described below. With the main disconnected, neither bus bar should show any connectivity to the other bar or to neutral/ground.

   With a reasonably high-impedance meter, check the resistance (ohms) between bus bar and wire connector for each of the REMOVED breakers (with the breaker switched "off"). Use a scale that will measure 100K ohms or better. Don't let your fingers touch the contacts and confuse things. Discard any breakers that show ANY continuity (any movement at all off the right peg, for an analog meter) between the two contact points. Also check (with the breaker switched on but still REMOVED) for any continuity between the power contacts and any sort of ground connection the breaker may have (some do, some don't). Again, discard any that show ANY continuity.

   I think you may have confused yourself by disconnecting the neutrals of suspect breakers. Here's a place where you don't want to use a high-impedance meter (or a neon tester). Use a small incandescent test light (eg, 6-25 watt bulb) or a "wiggy" as a tester. With a breaker installed but switched off (regardless of whether a wire's attached) you should get absolutely no glow on your test bulb, testing from the breaker terminal to the neutral bus. Likewise, with the breaker switched off and a wire attached, you should get no glow if you test between the circuit's disconnected neutral and the neutral bus.

7. 
   DanH | Apr 26, 2005 08:21pm | #8

   It sounds like you're describing "normal". If you don't understand that then you should get someone else to work on the panel.

8. 
   TROYLS1 | Apr 27, 2005 12:56am | #9

   "I have continuity between my hot and its matching common when the power is out.  If I energize the circuit I get 110 thru the hot and 110 thru the neutral."

   Is the breaker you are measuring in the on position and you say you are getting continuity with the main breaker shut off or you are opening and closing the breaker you are testing and getting continuity? I think one of us is confused...

9. 
   BillHartmann | Apr 27, 2005 03:00am | #10

   If you are using a digital voltmeter you can often get false readings due to capacitive coupling.

   get a 60-100 watt light and plug it into that the receptacle.

   Them measure hot to neutral at that receptacle. And if it is grounded then also measure ground to neutral and ground to hot.

   And report those measurements.

10. 
    DanH | Apr 27, 2005 03:49am | #11

    You're still not being clear. If you have a circuit that's attached to a "hot" breaker on one end, and disconnected from neutral on the other, and IF THERE IS ANY LOAD (eg, a light switched on) ON THE CIRCUIT, you'll read line voltage on the disconnected neutral wire.

    If there is no load on the circuit, and you use a high-impedance voltmeter or a neon tester, you'll still likely find the neutral wire to be "hot", due to capacitive pickup from the "hot" wire in the same jacket.

    Generally, neutrals should NOT be tied to the neutrals of other circuits in a box somewhere, but it does happen. Not code to have this, though.

    With BOTH the hot and neutral disconnected from a circuit, the circuit should be completely "floating". A high-impedance meter may read voltage on the circuit, but a wiggy or incandescent test light will not register anything. If you use an ohmmeter or other continuity tester, you should not find continuity from either of the disconnected wires to neutral or ground (though they may appear to be connected to each other, via a lightbulb or other load on the circuit).

11. 
    junkhound | Apr 27, 2005 05:57am | #12

    Can you draw and post a circuit diagram (including measurement points and model of meter used) so your terminology does not lead to further obfuscation?

1. 
   CPopejoy | Apr 27, 2005 07:59am | #13

   One thing that hasn't been brought up is, why did the breaker go up in flames to begin with? 

   Edited 4/27/2005 1:11 am ET by CAP

12. 
    Luka | Apr 27, 2005 10:26am | #14

    Take some pictures.

    Several pictures.

    Post them here.

    Explain what you mean, in the pictures.

    A person with no sense of humor about themselves, has no sense at all.