main breaker in house blowing

There are so many computers and air purifiers and television equipment hooked up It's surprising my breakers aren't blowing all the time but...

why would the main breaker blow? Seems like the individual breakers would go first. A new AC compressor was just installed and there is something weird because one of the other breakers for "lights" or something stops the AC when it is tripped. The actual AC breakers trip the AC too.

Tia, : -)

Reply to
AKA gray asphalt
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It's quite possible the total load is now greater than the panel capacity even though no individual circuit is overloaded.

If the breaker that you mention that stops the AC does something other than the inside air handler, you definitely have a problem.

Sounds like time for an electrician for some diagnostics and maybe the AC guys back to figure out whether there's something amiss w/ the wiring there...

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Reply to
dpb

When the new compressor was installed, who had their hands inside the breaker box? The HVAC contractor? "Handyman"? Your brother in law?

Reply to
JoeSpareBedroom

Is it possible that the *control* for the A/C is on a lighting branch circuit?

It is possible, especially if you have a lot of breakers, that if the A/C goes on it might be pulling only 30A on a 40A breaker but the cumulative load of everything in the house would be over 150A or whatever your main breaker is...

nate

Reply to
N8N

The "lights" breaker shouldn't affect a central AC system, unless it's a main breaker for a sub section of your panel, and the AC breakers are located in that sub section. If your service is too small for the loads in it, the main will trip. you need to get someone with an ammeter and take readings while switching on the circuits

Reply to
RBM

Hardly. Any central A/C would require 240 and 30A+ and I've never seen that kind of a lighting circuit in a residence. Unless, of course, some _real_ doofus mixed stuff all up and has multiple wires connected to a breaker or some other really, really weird stuff. But, even then, any lighting circuit would normally be only 15A or 20A max, not enough to keep from tripping...

That's certainly possible, and I'm guessing the new A/C was the straw that the camel wasn't happy to see...

I'm also guessing there's something else not right and OP needs a pro to evaluate what's what...

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Reply to
dpb

Had a problem that was similar to yours. Took amp. all OK . Problem was a bad main Breaker. Never thought it could happen,but it did.

Reply to
Frank

Bad main breaker is what the guys who installed the compressor are saying. Is it a difficult or dangerous thing to change? The breaker has pigtails the need to be unscrewed and it isn't clear how to shut off power between the main breaker and the feed. It doesn't seem right that 'standing or a board' would take care of it, insulation wise, as one guy told me.

It seems like replacing the main breaker might be cheaper and have a good chance of success instead of calling an electrical expert out to test the lines.

Reply to
AKA gray asphalt

You don't need to test the lines, but an ammeter will tell you if the main is tripping prematurely. They do go bad, but it's certainly not the first thing I'd be looking at, and definitely not guessing at

Reply to
RBM

May be an unbalanced load, one side is overloaded more than the other side of the line, tripping the breaker.

Reply to
EXT

That's just the sort of thing five minutes with an ammeter would determine

Reply to
RBM

You need an electrician.

Reply to
Meat Plow

or a knowqledgable person with a clamp on ampmeter.

if the main breaker needs replaced someone must pull the meter to do it safely.....

no biggie if you know how,

Reply to
hallerb

It would be unlikely that you are pulling enough load to pop your main breaker. I'll bet the breaker went bad. Get an electrician, changing it is not really a DIY job.

Reply to
J.A. Michel

It probably has the control transformer on it -- without the 24VAC from that, your thermostat won't be able to pull in the relays that control the compressor and air handler.

The actual AC breakers trip the AC too.

Reply to
CJT

Knowledgeable person = electrician or equivalent.

Yes the electric service provider must be notified. Around here they frown upon breaking their seal. Probably holds true with most.

I agree. The OP doesn't know how, he needs to find someone with experience. I had a stint as a commercial A/C installer (electrical) some years back. I know what it takes to be successful and stay alive at the same time :)

Reply to
Meat Plow

well I like working on electrcal but am not a electrician, but know how to safely pull a meter.

there are times it must be done, like a fuse breaking off in a fuse box. that happened to a friend, I pulled the meter and notified the power company on monday, fuse broke off saturday morning...

power company said they didnt care provided they were notified.

might be a bad main breaker or more likely a unbalanced load. my neighbor had that problem with christmas lights, he lit up the neighborhood, after a quick check we re balanced his legs and all was well:)

I fix office machines for a living but could of been a electrician, I wierdly enjoy the challenge of snaking lines and thru walls.

this reminds me I had some stuff fall over in the basement and destroy the plastic seal on the water meter. need to call them so they can reseal it......

occasionally do jobs for friends always for free, I like being useful:)

Reply to
hallerb

Personally I think the OPs mains breaker is weak if it trips more than once which should be a vary rare occurrence if at all. I did some work with an electrician years ago in my late teens. Learned and retained a lot from that years worth of experience. He did new home installs only so I didn't get any renovation/troubleshooting skills, those came later on in life. Recently I upgraded my girl's service from 60 amp fuses to 100 amp breakers. I'll have to call a friend to do the room by room rewire, I'm getting too old for that crap :)

Reply to
Meat Plow

Sounds like you guys kind of agree. It not apparent to me, though, why there is any case that the regular breakers would not trip before the main. Maybe it's beyond someone so ignorant of the way this kind of thing works.

Reply to
AKA gray asphalt

If you have a 200amp main breaker, with 20 20-amp breakers and 15 amps flowing through each of the 20 circuits, that's 300 amps total.

Which breaker will trip?

You can assume everything is working well.

If one breaker is getting weak, it might trip no matter what other breakers do, and no matter what the current.

Why not turn off the AC for a couple days and see if anything trips. Probably not since the AC was just added. Then you will have an idea of where the additional current is being used. Probably the AC is the culprit, but it's probably not using more than it should.

Then you can turn off everythign but the AC and see if the AC by itself trips the main breaker. Probably not, especially since it doesn't trip the individual breaker. but these tests interest me. If you get results that I or the others don't expect, you'll have a big clue as to the problem.

Or you could just take their suggested advice. They have more experience than I and they're probably right.

Reply to
mm

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