How often should breakers be changed ?

[goldstar]

Most homeowners believe that once they move into their homes and as long as they had a home inspection where the electrical system passed they are completely safe. I had a situation just yesterday doing a bathroom remodel where I had to shut off a circuit in order to work on it. I inadvertantly shorted the branch circuit feed to the side of the metal electrical box (PLEASE DON'T TRY THIS AT HOME BOYS AND GIRLS !!!) and the breaker took about 2 seconds to trip. Upon further investigation I found the breakers were the Square D QO type (probably one of the best breakers on the market) but also probably haven't been changed out since their original installation some 25-30 years ago. Does anyone know what the expected life is of circuit breakers in general and how often they should be changed out ?

[jwelectric]

Re: How often should breakers be changed ?

An advantage that I have over a lot of my fellow electricians throughout the nation is I have a lab at my disposal. I do all kinds of experiments in lab to let students see just what takes place in an electrical circuit.

We take an Edison base fuse, a time delay (type S) fuse and a breaker all of the 15 amp rating and load them with a variable resistor to the point that they open.

Wonder which opened first?
Wonder which opened last?

One of the things that I find truly amusing is the electrician that will sell a service upgrade from fuses to breakers and use the selling point that the breakers are safer than the fuses. Nothing more is done to the electrical system other than the service change. The homeowner now thinks that their home is safer because they had their house rewired by this electrician.

The homeowner still has the same number of circuits supplying the same conductors that are connected to the same devices that are just as old as the fuses were. The difference is the homeowner now has overcurrent that has a trip curve 4 to 6 times of that of the original overcurrent.

This type of service upgrade is like taking the old maid that lives down the street to a beauty parlor and having her hair, face and cloths all made up to look real pretty. When she walks out she looks a lot different but on the inside she is still the same old maid that lives down the street.

[Overbuilders]

Re: How often should breakers be changed ?

Mike,

Nice story about a fuses-to-breakers service change. Still, you haven't directly answered Phil's question. I am also curious if changing aging breakers is a maintenance issue or a waste of time and money.

[jwelectric]

Re: How often should breakers be changed ?

Still, you haven't directly answered Phil's question.

I was addressing the

the breaker took about 2 seconds to trip.

part of his post. Sorry I should have qouted that part in my post.

[Overbuilders]

Re: How often should breakers be changed ?

And then he asked...

I am also curious if changing aging breakers is a maintenance issue or a waste of time and money.

...to which there was also no reply...

[BillHartmann]

Re: How often should breakers be changed ?

I was addressing the part of his post. Sorry I should have qouted that part in my post.

But your test has nothing to do with this situation.

Sounds like the magnetic coil was defective.

"Standard" breakers have a dual trip system. A time inverse bimetalic trip with a heater. That is for overloads. And a magnetic coil for fast trips on high current faults.

SQ D has the trip curves posted on thier website. But takes some searching to find.

[jwelectric]

Re: How often should breakers be changed ?

And then he asked...

I am also curious if changing aging breakers is a maintenance issue or a waste of time and money.

...to which there was also no reply...

Oh yes, the answer is in the post if you know how to find it.

The homeowner still has the same number of circuits supplying the same conductors that are connected to the same devices that are just as old as the fuses were. The difference is the homeowner now has overcurrent that has a trip curve 4 to 6 times of that of the original overcurrent.

If I was going to worry about my electrical system needing attention I would worry about it as a whole instead of in parts.
Unless there is evidence of something failing or unless I am working the breaker a lot then it would not need replacing at a certain point in time.

But your test has nothing to do with this situation.

Sounds like the magnetic coil was defective.

I would tend to agree with you if it wasn’t for the fact that the overcurrent devices are chosen at random.

"Standard" breakers have a dual trip system. A time inverse bimetalic trip with a heater. That is for overloads. And a magnetic coil for fast trips on high current faults.

SQ D has the trip curves posted on thier website. But takes some searching to find.

The key here is the words “high current faults” and we are loading the overcurrent devices with a variable resistor where the load is increased slowly.
The Edison base fuse will blow at or close to the 15 amp mark but I have saw several 15 amp breakers of different makes hold for several seconds at over 20 amps.

[Overbuilders]

Re: How often should breakers be changed ?

Oh yes, the answer is in the post if you know how to find it.

Well I don't know how to find it. Too cryptic for me. Simple question, simple answer. Anyone?

[Diamond Custom Homes]

Re: How often should breakers be changed ?

Oh yes, the answer is in the post if you know how to find it.

As Denzel said "explain this to me like I'm a 3 yr old", 'cause I am missin' something. I too am curious how long the life is....

[jwelectric]

Re: How often should breakers be changed ?

As Denzel said "explain this to me like I'm a 3 yr old", 'cause I am missin' something. I too am curious how long the life is....

Until they break

[mdshunk]

Re: How often should breakers be changed ?

Circuit breakers don't get better with age. I find more failed breakers in damp basements, unconditioned outbuildings, and outdoor panels then I do in dry indoor panels. Circuit breakers rarely fail, and the 2 seconds you quoted can be within tolerance. I would never encourage wholesale replacement of circuit breakers at a certain time interval, unless certain environmental conditions prevailed. In that case, the panel and the breakers may well need changing at the same time. Horse and cow barns are one such example.

I agree that fuse protection is superior to breaker protection. It is for this reason that the MDP's of large commercial services often utilize fuses. You can get a "boutique" fuse with a fairly customized trip curve more easily than you can get a breaker to provide the same protection. To advocate fuses for residential services, while certainly meritorious from a technical standpoint, would be tantamount to business suicide.

[frenchie]

Re: How often should breakers be changed ?

I'm confused. Why don't they just make breakers with a trip curve similar to a fuse's?

[mdshunk]

Re: How often should breakers be changed ?

I'm confused. Why don't they just make breakers with a trip curve similar to a fuse's?

Then you're into an electronic breaker, and that would be prohibitively expensive for a resi panel.

[goldstar]

Re: How often should breakers be changed ?

To advocate fuses for residential services, while certainly meritorious from a technical standpoint, would be tantamount to business suicide.

There's no question that fuses will give you a faster response and better protection. However, your last sentence says it all in a nut shell. People old enough to have had fuse panels in the past would feel as though they were going backwards in time not to mention that replacement fuses aren't always kept readily available. It's much simpler to just reset the breaker irrespective of the trip curve.

I find more failed breakers in damp basements, unconditioned outbuildings, and outdoor panels then I do in dry indoor panels.

Good point.

Circuit breakers rarely fail, and the 2 seconds you quoted can be within tolerance.

I believe the vast majority of breakers on the market today are the "quick-open" type.

I would never encourage wholesale replacement of circuit breakers at a certain time interval, unless certain environmental conditions prevailed.

Another good point. If the breakers are corroded chances the buss bar and connections inside the breaker panel are also corroded.

[goldstar]

Re: How often should breakers be changed ?

One of the things that I find truly amusing is the electrician that will sell a service upgrade from fuses to breakers and use the selling point that the breakers are safer than the fuses. Nothing more is done to the electrical system other than the service change. The homeowner now thinks that their home is safer because they had their house rewired by this electrician.

Contrary to popular belief most of us are out there to make money. Selling a fused disconnect is a tough sell.

This type of service upgrade is like taking the old maid that lives down the street to a beauty parlor and having her hair, face and cloths all made up to look real pretty. When she walks out she looks a lot different but on the inside she is still the same old maid that lives down the street.

Please tell me you're not out there selling people fuse panels !! If you are, please don't admit it in open forum. You'll embarrass all of us who think so highly of you.