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  #1  
Old 03-13-07, 07:47 PM
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DIYrs Quiz

I have this situation to deal with .

Just a quick pole to see how anyone of you would attack this.
No right or wrong answer.

No grades-- just a sample of mind sets-- So perhaps we may be able to see how some think. So we can help you better.


Situation: A customer called regarding their house.
Their main ckt breaker (100 Amp) trips on occasion. This has been happening for several months now.(No one called me untill tonight).

It started out once in a while, but has become more frequent now. IE: Once a month, now almost once a week. They are able to reset it and all goes back to normal, untill next time.

No indication of usage or demands.


HELP:
Do I start right out with changing the main breaker?
Do I start with a service change?

Should I start by eliminating the branch ckts (All loads on panel)?
If so.. Start with the small(receptacles,lights) Or the large, (range,dryer etc.)?

If so, How should I aproach doing this?

I only hope to initiate a thought process, so some questions will be answerd themselfs and we will be here for confirmation (recommended).

When in doubt about it.. Ask about it.
 
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  #2  
Old 03-13-07, 07:58 PM
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If there's no evidence that they really are exceeding 100 amps, then yes, I'd change the main breaker.
 
  #3  
Old 03-13-07, 08:09 PM
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Readings have not been taken yet.

Crouse H panel.
 
  #4  
Old 03-13-07, 08:14 PM
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When I had my service upgrade done, I was told that if the main ever trips to call them back. I assume there is the possibility that the load is exceeding the main breaker, but this scenario could get ugly really fast.

I would do a quick and dirty load calc. I would look for any signs of corrosion or water intrusion. I would check for continuity with the main off.

I am a DIY'er, most of what I've learned is off this, mike's page, and 'lectric simplified.
 
  #5  
Old 03-13-07, 08:55 PM
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take a current reading. take a voltage reading. then inspect the system.

interrogate the home owner as to possible loads that may be causing this since they may not be active at the moment.

ask if the neighbors have any problems. (if a POCO low voltage situation, they may be having probs as well.)

I would look for loose connections or burns before condemning the breaker.(including the attachment to the buss bars)


If all shows good, then I would strongly consider replacing the breaker.

of course if they are actually exceeding the service capacity, I would do the upgrade.
 
  #6  
Old 03-13-07, 09:28 PM
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Wink

Id put in the new breaker right away. From what it has been doing the metal pop spring in it is just about shot.
Look for loose connections tighten all. Look for any burns or black spots all over . Amp out every line with everything on, on that line. Id also pull the rest of the breakers out and check if their stab in's look ok
 
  #7  
Old 03-13-07, 10:10 PM
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this what i will do here :;;

inspect for any FOD [ forgen Obeject Damage]

check for any loose connetion on main breaker and branch breaker

check for any burnt wires [ if any indacting of overloading ]

if no damaged like overheated or arc'ed bussbar then i will go ahead and replace the breaker

after the breaker replaced then check the current drawage to make sure it dont go over the main breaker rating.

check the voltage both loaded and unloaded to make sure dont have voltage drop isusse around there

Merci , Marc
 
  #8  
Old 03-13-07, 11:47 PM
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I'm definetly a novice here. But since I have had my main replaced I have learned a lot from this forum. I even had to correct some things that were done wrong by an electrician. In this day and age the first thing I would do is to try to convince the owner to upgrade. If the owner does not want to then I would find out if they have been using anything new that could cause this. Such as a new space heater. If not then I would do a visual inspection of the main and whatever else I could. If nothing was found then I would replace the main breaker.
 
  #9  
Old 03-14-07, 06:02 AM
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Main breaker

Check total load. Torque service connections and look for corrosion. Have power company verfy that incoming voltage is up to their specs.
 
  #10  
Old 03-14-07, 02:44 PM
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A piece of duct tape to hold the breaker works well........

.
..
...
....
..... Did I say that outloud?


[ John Nelson clarification ] THIS IS A JOKE. Do not do this.
 
  #11  
Old 03-14-07, 03:22 PM
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don;t worry Mark, it wouldn;t work anyway. A breaker is designed so that it will trip even if the handle is held "on". it;s a safety feature.

If you have ever seen breaker locks, you would understand.
 
  #12  
Old 03-14-07, 03:37 PM
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Thanks John for the clarification. It WAS a joke not to be taken seriously.
 
  #13  
Old 03-14-07, 05:24 PM
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My take:

1) Do a load calculation. Figure out if there is even a remote chance that the main _should_ be tripping. If possible, get a clamp meter reading of the load, with _everything_ on. Fact is that NEC load calculations are very conservative; if the calc comes out at less than the rating of the breaker, then there is no chance that the main _should_ be tripping.

2) Physical inspection. Look for any sources of extra heat, in particular: bad connections. This may mean disconnecting and reterminating the supply conductors. Watch out for corrosion situations where the lug screws are tight, but the conductor is not properly compressed.

3) If there is no evidence of bad termination at the lugs, then check the bus stabs. If there is evidence of arcing on the bus stabs, then a panel replacement is probably required.

4) If the terminations are good, and the bus stabs are good, then you've already committed yourself to the _labor_ of chaning the breaker, so change it.

-Jon
 
  #14  
Old 03-15-07, 05:54 AM
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Do an infra-scan.
 
  #15  
Old 03-15-07, 07:16 AM
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Originally Posted by mattison View Post
Do an infra-scan.
what, no lasers?
 
  #16  
Old 03-15-07, 06:00 PM
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Update

The customer has not called for a time yet. Must not be tripping.

This is a 2 family, so I won't go with out the owner, Tennant issues.

The weather here has been a bit mild, so overlaod is a thought. Maybe a bad appliance, stove etc; Sometimes when they go bad... It can go straight to the main.


I hope for homeowners to think and do some diagnostics first.
This will save some time if a pro is needed and provide great insight for you.

Trouble shooting is fun, Just logic and time (experience and knowledge makes it a bit easier). That's why I am asking for basic thoughts of the non-pro, and how they may attack a problem.

I often ask my Aprentice: "Before you ask-- stop and think". Then ask to confirm. Most times.. He is correct.
 
  #17  
Old 03-15-07, 06:09 PM
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Sell the house .
 
  #18  
Old 03-15-07, 06:26 PM
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NOT mine. If it were.... Not in this market.....I would.....

Thats the only idea I will offer.
 
  #19  
Old 03-16-07, 10:18 AM
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is the load balanced
 
  #20  
Old 03-17-07, 10:22 AM
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Been There Done That!!!

I had the same situation some time ago. After checking amperage on each hot leg and amperage on the neutral conductor I found that all readings were within acceptable limits, I then verified that the vlotage readings at the main were accpetable ,which they were ( 120 volts nominal in our area and I had a reading of 118). At this time I had the local supply authority remove the kWh meter from the socket to ensure that all connections were tight and not corroded (the system used NuAl conductors). When all this stuff checked out as normal, I turned off all circuit breakers and turned them back on one at a time with each circuit carrying extra load than what the homeowners would normally use just to check if one of the circuits was overheating the breaker under heavy load conditions. After all these items were checked ,I finally got smart and replaced the main breaker in the panel. This change was made on this panel at least 2 yrs ago and all seems well now. I have since returned to this customers house for other issues (adding in receptacles and upgrading fixtures) and they have had no further problems.
In my experiences, it is usually the main that is causing this problem.
 
  #21  
Old 03-17-07, 11:25 AM
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If aluminum wire is feeding the panel box, the main could be getting hot from a bad aluminum wires connections. Had this recently in a rental and the panel box was getting so hot you could fry an egg on it.

I don't like dealing with main breakers as they are (often?) live and energized with high amps no matter if breaker is turned on or off!

Because of this...if you treat a main breaker as if it was just some other breaker in your box...it can be very dangerous!
 
  #22  
Old 03-17-07, 11:38 AM
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I agree with all those who say that the main breaker is the most likely the problem.

However, if the main breaker became so hot as to continously tripp the circuit, it is possible that the buss bar where the main attaches could be dammaged.

I would replace the main breaker, and check back for heating on the breaker/buss bar for a few months.

Just use the back of your hand on the breaker to see if it is too warm.

You can even advise the customer to check for you, and call if there is a problem.
 
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