# oversized breaker on AC and Furnace



## dmxtothemax (Jun 15, 2010)

One possible explanation is that he is allowing
A little bit extra on the breaker to allow for
start up surges.
It can be a problem some times.
This might be his way of avoiding this problem.


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## Speedy Petey (Jan 10, 2007)

If the MCA is 23, and the max breaker is 35, putting a 40 on it is NOT complaint. Period. Even with #8. In fact using #8 for a 23A MCA circuit is just a waste of money in most cases.

Using #10 and a 35A breaker would be perfectly complaint for an A/C unit (not a furnace) and using a 30A would most likely be just right for pretty much any installation. 

Simply saying _"trust me I ve been doing this for years never had a problem" _is just ignorant.


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## backstay (Feb 3, 2011)

You should trust him because he has been "doing" this for years.


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## 480sparky (Sep 20, 2007)

visi said:


> ........ His only explanation was " i don't charge enough for my work to do it safely and correctly. I had 8 and a 40a breaker on the truck so I just hacked that in so i could get paid. It works so STFU."
> 
> thanks


fify.


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## BababooeyHTJ (May 31, 2013)

Speedy Petey said:


> If the MCA is 23, and the max breaker is 35, putting a 40 on it is NOT complaint. Period. Even with #8. In fact using #8 for a 23A MCA circuit is just a waste of money in most cases.
> 
> Using #10 and a 35A breaker would be perfectly complaint for an A/C unit (not a furnace) and using a 30A would most likely be just right for pretty much any installation.
> 
> Simply saying _"trust me I ve been doing this for years never had a problem" _is just ignorant.


Personally I would just use #10 or 12 if it isn't romex or too long of a run and a 30a breaker and call it a day. That 23a mca has 125% of the largest motor factored in.


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## Nutmegger777 (Mar 14, 2014)

Sorry to be the voice of the obvious, but aren't we talking about 110.3 (b)?
If the tag on the unit says "x awg conductors, y A breaker", you have to use those values, otherwise you are running afoul of 110.3?


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## ELECTRICK2 (Feb 21, 2015)

visi said:


> Hi, recently i changed jobs and stared installing Air Condition and Furnaces, one think that i ve come across is A/C that have on the tag max circuit breaker 25A or i had a furnace the other day that was calling for min ckt amapacity 23.5A max , max ckt brk 35A, the electrician that worked for the company a long time always upsize the breaker and the wire for instance for the furnace he went with 40A brk and #8 wire. am I missing something because with 40A brk we dont protect the equipment. ( we cant easily find 25,35 A brks). his only explanation was " trust me I ve been doing this for years never had a problem"
> 
> thanks


He may have been doing it for years and never had a problem but that doesn't mean much. He's upsizing the wire, not a problem with manufacturer specs just a waste of money. He's upsizing the breaker, directly against manufacturer specs. That's a problem. If you had a 15A receptacle that tripped the breaker once in a while would you just put in a 20A breaker and call it good?


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## AK_sparky (Aug 13, 2013)

Nutmegger777 said:


> Sorry to be the voice of the obvious, but aren't we talking about 110.3 (b)?
> If the tag on the unit says "x awg conductors, y A breaker", you have to use those values, otherwise you are running afoul of 110.3?


I can't find 110.3 in the CEC...which is used in the OPs province of Saskatchewan...


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## Nutmegger777 (Mar 14, 2014)

AK_sparky said:


> I can't find 110.3 in the CEC...which is used in the OPs province of Saskatchewan...


My bad :no: I missed the location! 
For my own future education, is there an equivalent to 110.3 (b) in CEC? (anything about installing the equipment per manufacturer's instructions?)


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## AK_sparky (Aug 13, 2013)

Nutmegger777 said:


> My bad :no: I missed the location!
> For my own future education, is there an equivalent to 110.3 (b) in CEC? (anything about installing the equipment per manufacturer's instructions?)


I'm sure there is, but I don't have a code book so I can't check. And my remote desktop machine at work is shut down for some reason, so I can't check the e-copy either....but I'm sure there is.


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