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I'm hanging new cabinets in a kitchen and was told by the owner that the refrigerator keeps "popping" the breaker. It is not on a dedicated circuit. It shares the outlet with living room outlets. I advised that an electrician should be called to install a new dedicated circuit.

Over the weekend the tenants father swapped the 20 amp breaker out for a 25 amp breaker. I advised that was not allowed, but he is an electrical engineer and says it is fine. The owner now is worried and fuming that the house is unsafe and this could affect her insurance. To complicate matters, the owner and the tenants father are brother and sister. She wants him to get the circuit for the refrigerator done correctly. He says that there is nothing wrong with what he did and the #12 wire can handle 25 amps. ( I know technically it can, but it is not allowed as far as I know. That is all I know.)

I got them to agree that they will do what an electrician will advise. However they do not want to pay for an electrician to come and just give an opinion. Thus I am looking for an one here. Officially I am looking for the NEC rule regarding this situation. As said I am not an electrician nor do I have the rule book.

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  • Code citation in the accepted answer: diy.stackexchange.com/questions/61521/… Commented Nov 1, 2023 at 12:56
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    Second problem is that you/or the owner and the tenant or Joe down the street cannot touch the panel breakers except to turn them off and on, in most areas. If it is the owner's house that only their family lived in it is okay, but once it becomes a rental, then they need a licensed electrician to do any work. Should be able to find out about needing an electrician in local codes on rentals.
    – crip659
    Commented Nov 1, 2023 at 13:03
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    Send an email to your state's board of professional licensing for engineers; ask if an engineering license satisfies a requirement to have an electrician license (it doesn't). In your request politely ask for the reply to be on official letterhead. As a licensed professional (electrical) engineer myself, I am confident that they will be happy to oblige, and that their opinion will carry some weight with your engineer friend. You don't need an exact code he's breaking, you need to remind him that his license (assuming he has one in the first place) ain't an electrician's license.
    – Ben Voigt
    Commented Nov 1, 2023 at 21:23
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    the regulations are deliberately on the safe side of what is fine. Will the house be much more likely to catch fire with a 25 amp breaker? probably not... short circuits will trip any breaker, the circuit probably isn't overloaded anyway, and if it is, there's probably enough safety margin in the cooling. But it's still not playing by the rules that are designed to ensure safety, so this is considered an unacceptable risk when the possible outcome is that your house burns down and you all die. Was it safe before? Yes. Is it safe now? Maybe, and maybe's not good enough. Commented Nov 2, 2023 at 15:42
  • @RMDman - if you're still around I'm genuinely interested in hearing how things turned out and how the convincing him he was wrong worked out. Was fridge [startup] amperage ever measured?
    – ron
    Commented Apr 9 at 18:25

6 Answers 6

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Table 210.21(B)(2): 15A and 20A receptacles must be protected by a circuit breaker/fuse no larger than 20A. 25A is not an option for any circuit with receptacles.

For example, even with the “right” 10AWG copper you may not put 15A or 20A receptacles on a 30A circuit.

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    This answer raises a very important point. Wire gauge specifications in the code are more than just for resistive heating. There are other considerations, like the geometry of conducting surfaces and load bearing capability of the connectors. The specifications don't say, "wire of size X or larger," because larger isn't necessarily allowed. Use the correct gauge. Commented Nov 1, 2023 at 21:32
  • @StephanSamuel Most devices will have a range of wire sizes to make connections. There is also too large of a size that is not allowed on the connection, and you cannot go below the minimum size. A bit different for a listed/tested device with it own wires.
    – crip659
    Commented Nov 1, 2023 at 22:16
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Your question was asking for Code references for what you already knew was wrong, there are several NEC violations represented here. First most clearly is:

NEC 210.21(B)(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or, where rated at higher than 50 amperes, the receptacle rating shall not be less than the branch circuit rating.

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If you find that too ambiguous:

NEC 240.4(D) Small Conductors. Unless specifically permitted in 240.4(E) or (G), the overcurrent protection shall not exceed that required by 240.4(D)(1) through (D)(8) after any correction factors for ambient temperature and number of conductors have been applied.

(6) 12 AWG Copper 20 amperes

Then you were spot-on when you advised a new circuit for the fridge, receptacle outlets in the kitchen should not be shared with those in the living room. There is some room for grandfathering if it was legal when installed, but altering a circuit requires meeting current Code:

NEC 210.52(B) Small Appliances.
(1) Receptacle Outlets Served In the kitchen, pantry, breakfast room, dining room, or similar area of a dwelling unit, the two or more 20-ampere small-appliance branch circuits required by 210.11(C)(1) shall serve all wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment.

(2) No Other Outlets. The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets.

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The guy is not an electrician, though.

Check with your city but you will find it is illegal for anyone to work on a rental unit except a licensed electrician. An electrician is someone who graduated high school or GED, trade school, and has apprenticed for 5+ years.

An electrical engineer is someone who went to college and got an EE degree. That only proves they muddled through college, it does not give them a "medallion" from the state permitting them to certify things as safe. That is a whole 'nother tranche of qualifications called a Professional Engineer.

But even if they have the Professional Engineer medallion, their "opinion" must take the form of a written plan, with their license number, filed. That's how the enforcement works - the board finds that paper, goes "this was a very bad design, you should not do this work anymore" and your career is over. What makes PE's advice good is that none will risk the lifetime invesment in their career by being caught giving bad advice. (also, PEs are personally liable for mistakes- which means, they need insurance.) And this is backed up by good safety culture among PEs - making them unlikely to do a thing like this or even give electrical advice unless they are dead nuts sure.

NEC is designed by engineers and sets out the standards for facility wiring in North America. It reduces the engineering down to a "paint by numbers" system that is buildable and verifyable by non-engineers so you don't need a PE to certify every house. It says "this is the way".

NEC does provide space for PE's to override some things in industrial facilities under direct engineering supervision (i.e. have PEs on staff), but not in a residential context.

So this "engineer" is either a PE who is cattily doing this in a deniable way so they can say "I didn't do it, my child did after misunderstanding a conversation". Or is not a PE at all, and is just a jackass with an opinion.

Either way, the "engineer" is not a licensed electrician, and has no business touching AC mains on a rental property. The person can do DIY work on the single family home they own and occupy, but in our experience it's a bad idea lol. EEs make the worst DIYers.

The 25A breaker won't fix a broken fridge, anyway.

Refrigerators normally draw 1-2 amps. This is a surprise to some people who feel 600W worth of heat coming off of them and figure they must surely be high power appliances. They're not. On average, your Comcast cable TV box uses more power lol - or used to, until Comcast was shamed into reducing their idle power consumption.

A fridge can make 600W of heat from 100W because it uses a physics cheat code - it's a heat pump.

So… If it's tripping a 20A, it has problems and is just as likely to trip a 25A.

Since the 25A breaker cured it, what's really happening is they are putting more than 19A of load onto the circuit, and either knowingly denying this, or simply being oblivious to the usage of their appliances.

I would ask the city inspector for advice, because it's well within their rights to slap an orange "unfit for occupancy" notice on their door, and really put the squeeze on them. If they wanted to help you. Now the tenant is the the author of non-permitted work, and they can sort it out with the city.

I'd meet them halfway and say I'd pay for a dedicated refrigerator circuit if they'd fix the breaker.

And then they find out that by changing it, they broke the grandfathering, and it needs to be AFCI now. Whoops!

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Fix the Refrigerator

Any US standard residential refrigerator is designed to run on a 15A circuit. In fact, most would run fine on a 10A circuit, but 15A and 20A are the standard receptacle circuits.

A refrigerator that pops a breaker, 15A or 20A, more than once a month (even that is a lot) needs to be repaired or replaced.

If the problem is actually the total including other stuff - e.g., if the living room receptacles on the same circuit are routinely powering HVAC equipment of other large loads - then you need a separate circuit. New builds require the living room and kitchen on separate circuits anyway, as listed in another answer, but older houses are grandfathered with most requirements unless the circuits are actually changed.

All other issues regarding rentals apply, but the above applies to any home, rental or owner-occupied.

Heading Towards Disaster

There is an additional problem beyond the current refrigerator issue. Hypothetical, but not so far-fetched, scenario:

  • Refrigerator gets replaced in a year when it starts tripping the 25A breaker or just breaks altogether.
  • 25A breaker stays in place because "whatever" - Who even turns off a breaker when replacing a plug-in appliance, let alone checks if it is the right size? Certainly not the appliance delivery guys - not their job.
  • Heating system breaks during a serious cold snap.
  • Tenants plug in not one but two standard 1500W (12A) electric space heaters in various receptacles on this circuit.
  • You now have 26A (2 x 12A space heaters + 2A of lights and stuff) running for hours at a time on 12 AWG wire.
  • Your wiring overheats and burns the house down.
  • The 25A breaker never trips because a standard trip curve allows for a little bit over 100% to run for at least 2 hours, allowing for manufacturing tolerances and other issues. It might trip in about 2 minutes. But it very well might not trip EVER.

That same 26A on a 20A breaker would trip in somewhere between 1 minute and 1 hour, which combined with 12 AWG being able to handle 24A (or more) for a moderate amount of time under most conditions, avoids a disaster.

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    It’s entirely possible that there’s just too much stuff on the circuit (shared with the living room). There is not necessarily anything wrong with the fridge.
    – nobody
    Commented Nov 1, 2023 at 13:41
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    The other maybe is that the old breaker had reached its end-of-life. Commented Nov 1, 2023 at 15:07
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    If the breaker is still working correctly, it has to be regularly facing a 30+ amp load to be popping.
    – KMJ
    Commented Nov 1, 2023 at 16:28
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    Today I found out that the only thing s sharing the circuit are a computer and monitor. 2 lamps and a 55inch TV with a cable box. It's in Fla. no space heaters. I'm thinking it's the refrigerator that's the problem , also. Thanks to all that spent time with comments and answers.
    – RMDman
    Commented Nov 2, 2023 at 0:42
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    @ namassehkatz, I agree...but convincing the "engineer" is difficult. Newest twist I found he ordered all new appliances for the kitchen, EXCEPT a new refrigerator, because "It was still working" I'm dealing with a dufus!
    – RMDman
    Commented Nov 2, 2023 at 16:54
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He says that there is nothing wrong with what he did and the #12 wire can handle 25 amps.

The others have answered why this is a bad idea, but I thought I would point out where your electrical engineer pal got his idea from.

The catch on wires and ampacity ratings is the ability of the sheath to endure heat. Being an engineer, he probably knows a lot of technical specs, and one of them is that there is 60°C, 75°C and 90°C rated wire. The wire size doesn't change, just the sheath material. As such, 12 gauge wire at 75°C rating can indeed carry 25 amps. The types of cable that encompasses are THW, THWN, SE, USE, and XHHW. The next level up has XHHW-2, THHN, and THWN-2 (all 90°C), which are rated for 30 amps.

It's very possible that an electrical engineer runs into that type of wire/cable all the time. The catch here? If you opened up the walls it's very likely it's all NM-B, which is 60°C. The max rating there is 20 amps. Unless he can show you where the cable in the box is one of these higher rated cables, he should assume it's NM-B and put it back down to 20, or he's creating a fire risk.

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  • Please understand 3 things: 1- He is NOT my pay, buddy, friend or anything other than a current PITA. 2- I agree with everything you have stated. 3- Thank You for the techy stuff on sheathing temperature.. That may finally be the stuff that convinces him he has done the wrong thing.
    – RMDman
    Commented Nov 3, 2023 at 21:01
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The refrigerator is probably tripping the breaker during compressor start, this maybe a sign of future failure. I would check the amp draw of refrigerator while it is running and compare it to nameplate rating. To alleviate the fears of the home owner. I would put a 20 amp Edison base fuse after the 25 amp breaker in a pigtail lamp holder. The fuse will protect the wire and allow the refrigerator to run. However the best remedy is a dedicated outlet.

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  • the best remedy would be to first analyze the load(s) on the circuit to determine what is actually taking place before running off the rails describing what could happen. No detail in that regard was ever given... to bad Jerry Springer wasn't still around this could be an episode... you're renting from your aunt and your dad changed the breaker.
    – ron
    Commented Apr 9 at 18:22
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    not to mention simply changing out a faulty 20A breaker with a new 20A breaker could have been the best remedy
    – ron
    Commented Apr 9 at 18:54

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