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Bathroom Wiring: 12 AWG vs. 14 AWG

09/28/2009 10:25 AM

An electrician told me that per code you must use 12 awg in a bathroom, and you can use 14 awg thru the rest of the house. He did not explain the reason behind it. Any ideas??? and is it per code?

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#1

Re: 12 awg versus 14 awg

09/28/2009 10:30 AM

14ga wire is rated at 15 amps. This is used for lighting circuits.

12ga wire is rated for 20 amps and is used for power (receptacle) circuits.

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#2

Re: 12 awg versus 14 awg

09/28/2009 10:31 AM

I'm not an electrician, but if I had to guess, I would sum it up in two words: Hair Dryer.

Other than an electric stove, clothes dryer, or AC, the common hair dryer is one of the highest wattage devices in the home. Luckily, it's only used for short periods of time.

Tom

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#3

Re: 12 awg versus 14 awg

09/28/2009 11:59 AM

Electrical installations in bathrooms have a special reference to Building Regulations part P in the UK, requiring a test certificate be raised by an appropriately-qualified person upon completion, and have a special section of reference in British Standard 7671. Socket outlets, other than those provided as isolated outlets for 110V and 230V mains-powered shavers, are not permitted.

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#4
In reply to #3

Re: 12 awg versus 14 awg

09/28/2009 12:10 PM

He is residing in the US......................

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#5

Re: 12 awg versus 14 awg

09/28/2009 1:09 PM

Unless your local code specifies 12 AWG the answer is no. IAW NEC 210.8 all that is required for a bathroom is a GFCI. A GFCI is required for any receptacle that is within 6 ft. of a water source. ie:sink, tub, shower, wet-bar, pool etc. or is outside or below grade or on the roof.

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#6
In reply to #5

Re: 12 awg versus 14 awg

09/28/2009 2:28 PM

All bathrooms must have at least one 20A power circuit.

Kitchen, pantry, breakfast room, and dining room must have at least two 20A power circuits.

The laundry room must have at least one 20A power circuit.

You may wire up to 600 square feet of living area on a 15A circuit or up to 800 square feet on a 20A circuit.

All 20A circuits shall carry their load on a 12Ga copper conductor.

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#7
In reply to #6

Re: 12 awg versus 14 awg

09/28/2009 5:58 PM

I stand corrected. As per NEC 210.11

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#8

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/28/2009 11:24 PM

Any electrical appliance that consume high current like hair dryer (with heating element), Hot water shower (with heating element), refrigerators (with compressor motor) and other appliance in kitchen and bathroom need a 20 amps power (receptacle) circuits. These are the highly electrical power consumable equipments. For lighting 15 amps pre circuit will be enough.

Bigger wire size able to carry higher current and help to reduce the wire overheated and prevent short-circuited. Most wire overheated is from the kitchen and the bathroom appliances.

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#9

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 1:07 AM

I had occasion to be looking after my son's 2br/2bath condo that he had rented out while he was away on an extended business assignment. The tenants were two young women. ........ You guessed it.

Second day in the unit one called and complained that the electricity went out whenever the used a hair dryer in the bathroom. Next day I looked the problem over and finally concluded that the old breaker had been tripped so many times that it was starting to derate and trip at lower current levels. A new 15 amp circuit breaker was the answer; problem solved!

A couple of days later I got the same call again. Sometimes it's a bit difficult to communicate across generations and cultures, especially when the people on the other side are fairly non-technical. I finally realized they had both used their hair driers at the same time. Duhhhh ... young working women ....similar living schedules.

Turns out that the builder had put both bathrooms on a single 15 amp circuit when the building was built some 30 years ago. The women just couldn't understand why they weren't able to use their hair dryers at the same time. I finally convinced them that we were in no position to build in a second circuit and that if they were both in a hurry to get ready to go out that one could go in the kitchen and plug in one of the hair driers there. They were happy and turned out to be excellent tenants.

Ed Weldon

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#10

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 8:10 AM

Maybe I'm old fashioned or just plain old but I make it a point to always use #12 as a minimum for all residential wiring. This use of #14 is a fairly recent development and as far as I am concerned, a mistake.

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#11
In reply to #10

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 8:30 AM

Did You ever try to wrap 12g on the screws of a gfi?

oilcan13

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#22
In reply to #10

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

10/02/2009 7:32 PM

I don't know about recent; my parents' house was built in the mid sixties mostly with #14 and 15 amp breakers. Even my old farmhouse with its cloth and resin wire running through / across ceramic tubes and knobs is mostly 14.

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#12

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 9:54 AM

The NEC requires bathroom receptacles to be 20 amp circuits. (NEC 210.11 3 C) The small conductor rule in the NEC would require #12 wire to these locations. In general, only bathroom receptacles may be on this 20 amp circuit (there is an exception, but read NEC for details).

The rest of the house cannot be wired in #14. The NEC requires 20 amp circuits for the following locations:

Laundry NEC 210.11 3 B

2- kitchen countertop circuits NEC 210.11 3 A and 210.52

Other equipment (dishwashers, furnaces, air conditioners, etc) require wire sized per manufacturer's installation instructions.

In fact, #12 may not be large enough for a good installation in a large house where the receptacles are a long ways from the service. The run may be increased to #10 AWG to prevent excessive voltage drop.


Your buddy does not know how to wire.

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#13

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 10:18 AM

I'm not a licensed electrician by any means but I've studied residential wiring practices and have reviewed the code many times. So, here is my two-cents worth regarding residential wiring:

12Ga wire will fit around the screw terminal of receptacles. I don't recommend using the strip-and-insert type of receptacles. The screw terminal is a much more secure way of attaching and the installer has complete control over the quality of the connection. When stripping the end of the wires, be certain that the copper is not nicked AT ALL as the copper will eventually break at this nick.

Never put more than one wire under a screw. Use a short piece of 14Ga wire and a wirenut to attach two 12ga wires to a terminal (two 12Ga and one 14Ga wire under a wirenut). Check the security of the wirenut connection after installed. wrap wirenut and wires with some electrical tape. Install a wire under a screw in a clockwise direction only. The last thing we want is an arcing wirenut or a screw terminal from a bad connection.

Always check the receptacle with a circuit polarity tester once power is applied. A mis-wired receptacle will play havoc with a computer or other type of electronic appliance. These all have a line filter in them, some on the hot wire side only, and rely on the ground to return unwanted noise filtered from the hot wire to the distribution box and ultimately the house's ground. So, it is imperative that the hot and neutral are not reversed and the ground is good.

When installing a light fixture in the ceiling, DO NOT cover the top of the fixture with ceiling insulation - it needs to breathe in order to keep cool. Never use a bulb that is a highr wattage than the fixture calls for. If more wattage is needed, replace the fixture.

Never run the cable over rafters - they can be stepped on. Instead, drill holes in the side of the rafters and run the cable thru them.

Never run cable under appliances in the attic or anywhere else for that matter. A stopped up drain on an A/C drip tray could leak over onto the cable and rot it out to the copper conductors(I've seen this happen).

Work safe, ensure all connections are secure, and good luck.

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Anonymous Poster
#14
In reply to #13

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 11:18 AM

Speaking as a licenced master electrician in Canada ,I question some of the advice given.I would only adhere to your NEC and any State, City or Local Utility Codes . As in Canada ,not all jurisdications have the same codes . Hire a professional to perform the work. If your juridiction allows you as a home owner to perform the work, at the very least have a professional inspect the work.

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#15

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 12:17 PM

Appliances, especially hair dryers, and motor driven devices pull much more current than lights. 12 gage wiring is code for bathrooms and kitchen (refrigerator, range, microwave oven, other plug-ins) circuitry as well as independent circuits for washer, dryer, furnace and dishwasher where you are likely to have devices plugged in that pull upwards of 9 amps themselves (typical) with start up current in the 12 amp range. 12 gage wiring will have less voltage drop than 14 gage wiring for a given load ... basically it will have less heat build up for a given current. If you plug in more than two devices on one circuit and operate them simultaneously it is likely that you will pop the circuit breaker at the breaker box and then you will have to reset it and unplug one of the devices. A 20 amp circuit breaker is used on these circuits. FYI: A 20 amp circuit breaker is typically good for 25 amps of inrush current for a few milliseconds for motor device operation. The 1st plug in the 12 gage circuit downstream from the circuit breaker box should be a GFI (Ground Fault Interrupt) plug to prevent inadvertant shock hazard. This is especially true of a bathroom where water is close by.

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#16

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/29/2009 1:24 PM

This requirement is, in my opinion at least, not technically sustainable.

The breaker on a 20A circuit (#12) is usually rated at 20A and since most breakers are rated at 80% of their listed value, the continuous current is limited at 20x0.8 = 16A.

For the #14 wire, listed for 15A circuits, the continuos current is limited by the corresponding 15A circuit breaker to 12A.

This is for "continuos load" meaning 2-3 hrs of that load, so that the heat developed in the conductor shall stabilize its temperature, which is very unlikely in a bathroom.

The code (NEC) per se, is not a design document, it is part of the NFPA (National Fire Protection Association) publications.

In the Notice about NEC, it states " The NFPA has no power, nor does it undertake, to police, enforce compliance with the contents of this document. Nor does the NFPA list, certify, test or inspect products, designs or installations for compliance with this document...."

All recommended sizings are usually "overkills" to avoid possible fire hazards. So basically, in theory at least, an electrical engineer is supposed to apply his/her own engineering judgment to size distribution, circuits, etc.

The main issue is that the approval of projects by the authority having jurisdiction (AHJ) is done, in lack of any other recognized comprehensive document, based either on the valid version of the NEC or, im case of some states, based on the State Electrical Codes ( for ex. California). That local code is basically the 3-years earlier version of the NEC with some very minor changes/additions.

It takes a lot of time and effort to try to justify something that is, based on sound engineering judgment, correct, but deviates from the code recommendations, so most of the designers simply select values recommended in the code, even if the selected values are, in some cases, way oversized for the purpose they are intended, just to avoid review bottlenecks.

So, it's like having a speed limit of 65 mph, local authorities chose to apply a safety cushion of 20%, bringing the limit down to 52 mph, just to make sure that fewer accidents and/or with less serious consequences ...etc.

Of course, doing along this type of reasoning, you may lower further to 42 mph, etc when, at a certain level, you ask "how low is technically/economically reasonable ?".

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#17

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/30/2009 2:35 AM

14 awg wiring in a home should be outlawed! I will not wire a home with anything less than 12 awg, 90 degree insulation copper for all lighting and standard receptacle circuits. Period. The extra cost is more than justified. Strip and poke outlets should be outlawed!

Special circuits for electric range, clothes dryer, baseboard heaters and all circuits that are required to be stand-alones are wire sized and breakered according to their individual ratings/needs.

House wiring is not rocket science and exceeding the bare minimum codes is the Only way to go. After 35+ years of wiring many 100's of homes and businesses, I've Never had a circuit failure or fire. (lucky? maybe)...(I don't use $0.20cent outlets or switches either)

It doesn't take any more time to do-it-right than to do-it-wrong.

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#18
In reply to #17

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/30/2009 7:53 AM

I agree that all residential wiring should be done with 12Ga only. I understand that there is less waste when using only one gauge. Should the <600sq. feet areas still be protected with a 15A breaker?

Strip and poke devices I don't trust either. A real electrician will take the time and use the screw terminals.

Remember aluminum wiring? Whose hair-brain idea was that anyway?

Also, it's not just the code - is about safe and reliable wiring practices- don't you agree?

I've always had a saying "Do it right the first time and chances are you will never have to go back and do it again".

GA, by the way...........

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#20
In reply to #18

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/30/2009 12:54 PM

Hello tropicalspeed

Should the <600sq. feet areas still be protected with a 15A breaker?

The main object of a circuit breaker is to protect the wire. Built into most codes (NEC & local) are buffers (overkill) designed to help make sure that, as long as you stay within the rules, the chances of a fire will be greatly reduced. Since the rules allow 20A breakers for 12awg wire, that's what I use. I never wire more than 2 adjacent rooms (depending on size) for lighting per circuit. I actually prefer 1 room/circuit especially with the greater use of ceiling fan/light combos.

Also, I use a 3A per receptacle rule so I never place more than one room or 6 outlets on a single 20A circuit. Less chance of trips that way.

I still find copper clad aluminum wire quite often. I don't like it and will always remove it when the opportunity arises. The same goes for knob & tube and anything with the name Federal-Pacific stamped on it.

You can't go wrong if you stay within codes and use common sense best practices when dealing with electricity.

I often send people with questions to this site. Or recommend the book "Practical Electrical Wiring".

Btw, thanks for the GA. I always appreciate them.

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#19
In reply to #17

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/30/2009 12:29 PM

You say you favor outlawing the use of #14 in homes. It is my understanding that you used only #12 and as a consequence you had no circuit failures and/or fires.

If you look at the statistics of circuit failures & fires, most of them were caused by bad connections and not by a conductor being undersized (#14 vs #12). While I do not share your opinion on wire size, I agree that strip & poke outlets provide a more unreliable connection.

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#21
In reply to #19

Re: Bathroom Wiring: 12 AWG vs. 14 AWG

09/30/2009 1:27 PM

Hello tomad

It is my understanding that you used only #12 and as a consequence you had no circuit failures and/or fires.

Yes, that is correct. I also never used any shoddy wiring devices or techniques. So that probably added to my track record to date.

While I do not share your opinion on wire size,

That's ok. It has always been my preference to use 12ga., especially in modern times with the greater use of higher powered electronics. I don't think that 14ga and 15A breakers are sufficient. Also, I've found far more 14ga circuits operating on the very-warm-to-touch-hairy-edge than 12ga. circuits. Thus, a greater chance of insulation failure over time. So, I simply refuse to use 14ga wire in a home or commercial business.

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Anonymous Poster (3); Ed Weldon (1); GX (1); Jerry New Hampshire (1); noshorts (2); oilcan13 (1); PWSlack (1); Simon Wan (1); snygolfgs (3); tdesmit (1); tomad (2); tropicalspeed (5)

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