Help. What is the correct way to report a breaker that is too big.

[Nick Gromicko]

I keep seeing reports that call a breaker too big for the circuit it's protecting as "Over Protected."

Why wouldn't it be "Under Protected?"

A breaker that is allowing too much current to pass through wires that are too small would be under protecting the wires... no?

[Paul W. Abernathy]

Nick,

Oversizing a breaker would not be safe in the same term as oversizing a fuse would not be safe.

If a conductor is 14 AWG and is designed to be protected by a 15A OCPD...in order to ensure the wire does not overheat....putting larger breaker on it would reduce the likelyhood the breaker would trip before the conductor exceeds it rating.

Now where you see smaller conductors on larger breakers under the exception of the NEC is for allowance of start up conditions and so on and demands someone having that KNOWELDGE of why it is done..but in general in normal branch circuits oversizing a breaker is the same as oversizing a fuse....the OCPD is there to protect the conductor itself..and in turn the house....

Over Protected is not a good term........UnderSized Breaker or improperly sized breaker is the better term in the case of the example I posted above.

[Nick Gromicko]

Good answer, but it's not to my question.

My question is not the use of the term "oversized breaker" but the term "overprotected circuit"

IMHO an overprotected circuit is one that has an "undersized" (small) not oversized breaker.

What say ye Guru?

[Michael Larson]

Should read "Breaker is oversized for conductors being protected and be corrected by a qualified electrician. Failure to do so may result in a fire if the circuit is overloaded.

[Jeffrey R. Pope]

"Over-fused" is the term I use whether it's a breaker or fuse.

I've never heard the term "over-protected" used for the condition you've described.

[Doug Edwards, CMI]

We see it often in the Service Disconnects. Wire is 15 AWG with a 20 amp disconnect (breaker). I've been told by electricians this is not critical for this application. What is the truth? Their response is the Service disconnect is little more than an On/Off switch.

[Nick Gromicko]

Jeff, you use "over-fused" to describe a breaker that is too small or too big?

[Paul W. Abernathy]

Originally Posted by gromicko

Good answer, but it's not to my question.

My question is not the use of the term "oversized breaker" but the term "overprotected circuit"

IMHO an overprotected circuit is one that is "undersized" not oversized.

What say ye Guru?

Depends on why you are using that term and if someone insists on using an improper term to get through life.

Lets talk about a general branch circuit...if I place a 30A breaker on a 14 AWG conductor ( not using the exceptions here )...then the conductor has a rating of 15A as defined by the NEC.....now if the load upon that breaker exceeds the 15A rating ( for simplicity sake ) it will heat up and eventually trip the breaker......now at the rating of a 30A breaker...chances are it will far exceed its relative rating where as a normal 15A breaker would have tripped.......saving a potential ground fault condition and so on possibly.

Your question is because of a use of an improper term.....

NOw I would agree with your view......could it be considered over protected by putting lets say a 15A breaker on a 30A circuit with 10 AWG conductors...sure....but being over protected would imply it will still function and in the case of the standard rating of the breaker which in this case is 30A it will shut down in a condition where it should not.....so I guess you could say it is over protected....if it helps ya sleep at night...I prefer to in this example call it Improperly Sized to the conductors being served.

[Jeffrey R. Pope]

Too big. . .

An over-fused circuit is one where the breaker is too large to adequately protect the conductors. . .

[Nick Gromicko]

I see breakers that are too big being referred to as "excessive overcurrent protection."

IMHO this is wrong. A big breaker is not protecting excessively, it is under protecting for overcurrent. No?

[Jeffrey R. Pope]

See OVERFUSED

http://www.inspectech.com/content/glossary.asp

[Nick Gromicko]

I say that "over protected", "over protection", "excessive overcurrent protection" are phrases that are being used incorrectly to describe a breaker that is too big.

Anyone disagree?

[Michael Larson]

Nick the terms-Excessive overcurrent protection and Over protected are used incorrectly when describing the situation you posted. It's that simple and anyone using those terms doesn't get it!

[Paul W. Abernathy]

Originally Posted by gromicko

I see breakers that are too big being referred to as "excessive overcurrent protection."

IMHO this is wrong. A big breaker is not protecting excessively, it is under protecting for overcurrent. No?

Yes, in the case of the examples it is NOT offering the protection it is designed for in the case of an overload.

Being a breaker normally is an inverse timed breaker its trip point changes based on the level of fault current but thats a whole different story.

Best terms to use -

Undersized Breaker or Oversized Breaker........or Undersized Fuse or Oversized Fuse....clean simple and to the point.