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20A circuit on 14/2

6K views 43 replies 15 participants last post by  Yoyizit 
#1 ·
I have a couple 20A circuits in my house and noticed they're all on 14/2 wire. I know this is against code and should be 12, but it is existing wiring.

My question is, is it safe? Can 12awg handle 20A safely without posing a hazard? I know the code slightly over sizes to be on the safe side. I have two spare 15A breakers so I could switch out the circuits that I think are more likely to hit over 15A, but I wont be able to cover them all. It's not like they're using 20A constantly, but if it really is a big hazard then I will want to fix that, probably by buying some 15A breakers to replace them.
 
#2 ·
it is a big hazard. This means that an overload will burn the wire before the breaker trips. When the wire burns (it is inside the wall) the house burns. The code is a minimum standard not overkill. 14 wire on 15 amp breakers. 12 wire on 20 amp breakers. Size the breakers to whatever wire size is there.
 
#4 ·
it is a big hazard. This means that an overload will burn the wire before the breaker trips. When the wire burns (it is inside the wall) the house burns. The code is a minimum standard not overkill. 14 wire on 15 amp breakers. 12 wire on 20 amp breakers. Size the breakers to whatever wire size is there.
Bob.,

If I were you I will becarefull when you stated that word.

Let you know I am not being harsh but give you a head up we sized the breaker with smallest conductor in the circuit so if that person have mixed bag of #14 , #12 , #8 AWG sizes what I do ? size the breaker to the smallest conductor which it is #14.

The other thing KBsparky mention A/C unit there is extempt from the regulations this is used for hardwire A/C plus hardwired motors and it is stated clear in Art 430 for motors Art 440 for HVAC motors so that is one of few spots but again that is limited useage. { typically we will sized by mimuim running amp and max OCPD size per nameplate info on it }

Merci.
Marc
 
#11 ·
WADR (With all due respect) Where the "Code" allows oversizing (of 25% (125% of proper wire size) is with the overload protection for motors in an industrial setting. For several reasons. (BTW I'm just stating the obvious) a) A motor draws more at starting time than its running rating; b) The motor has internal Thermal protection; Whereas in a residential setting, the motors are small enough to be covered for the starting load, too.
 
#5 ·
Yes, #14 has some spare "room" in the rating
Table 310.16 (cable) lists it as 20a @ 60 & 75 degree, 25a @ 90 degree
That's with an ambient Temp of 86

310.17 (free air) lists it as 25a @ 60, 30 @ 75 degree, 35a @ 90 degree

Each column is different types of wire too

Would I be worried about it? Only if you think you will be pulling 15a+ for a while - continous load
I've pulled ~2600w on a 20a circuit for about 3-5 minutes before it tripped

I would upgrade it when you can...better sooner then later
Years ago there were not as much electronic devices as these days

12awg can handle 20a...I think you are asking about 14g tho :wink:
Are you sure its 14g wire....marked ?

Problem with running 15a at higher then its rating is you will heat up the wire
That can possibly cause a fire before the breaker will trip
 
#6 ·
Yeah pretty sure it's all 14 but I'd have to check every single cable to be sure, could be there actually is some 12. This house was built in the 60's so maybe it was not code then and they just used all the same wire. It is labeled "industrial wire" if that matters.
 
#12 ·
Yeah all wires are green, I was reading off of them. I actually saw one that is 12 coming out of the panel. I'd have to trace it. There's lot of places I can't trace like what is inside the walls so could be it's 14. Think I'll just go ahead and swap the breakers to be on the safe side. The only 20 amp I know is ok is my dishwasher because I ran that cable.
 
#15 ·
Our neighbors about 1/2 mile down built a new house a year ago, they left the garage outdoor flood lights on overnight and burned the whole house down, not sure on specifics but the electrical contractor put in 14 gauge on a 20 amp for the floods and it overheated in the garage attic. They just finished rebuilding for the 2nd time.

I have a question on topic about loads and construction. My dad was an electritian for 37 years, and I swear he finds more "issues" with electric than any builder or home inspector. When he built his house about 10 years ago, he ran everything on 12 gauge and in conduit. I thought at the time that it was a little overkill.

Anyhow, with 150 or 200 A service on nearly every home built, why do the builders mix & match 15 amp / 14 gauge & 20 amp / 12 gauge. My service panel is about 1/2 15's and 1/2 20's. Kitchen & Baths on 20's .... Bedrooms on 15's. Now my house is roughly 20 years old, if I want to add a computer and desk light to my sons bedroom I will likely need to fish 12 gauge and rewire 2 bedrooms.

Why can't the builders just run 12 gauge everywhere so there is a little extra when / if needed? Is this some penny pinching electrical engineer deciding that 14 gauge will save $0.11 per foot in construction, or is there a safety concern with having 12 gauge only carrying minor loads?
 
#16 ·
Cost of copper, why use 12g when its not needed?
Making more $$ is the bottom line
Lighting circuits can account for a lot of wire
Have you seen the gauge wire that connects lights to the circuit wire?
Its not 12g or 14g, usually 16g & smaller

2 floodlights burned a house down? What wattage? What else was on the circuit?
Did the fire Inspectors report blame the 14g wire or somethig else?

We had a friends house burn down due to a defective radio
You don't need defective house wiring for that to happen
 
#17 ·
Thanks Dave, I thought it was a cost thing. I heard everything about the fire second hand. Old farm, they built a new house on a different part of property. What I heard was the fire inspector claimed "IMPROPER WIRING" in the garage, from the newspaper. A different neighbor that makes juice (works at the power plant) said the electrical sub had 14 gauge for the whole garage, including 2 100 W floods that lit the driveway (long, country drive), deep freezer, and whatever else was in the garage. He thought it was on a 20, because it didn't trip. It was really sad to see an older couple with an 80 y.o. farmhouse, build a beautiful log cabin (@2,500 sq. ft.) with 2 story fieldstone fireplace and have it burn down inside of 2 months after compleation. Nice to see that they are now rebuilt again.... very nice home.
 
#18 ·
I would prefer to buy & run 12g & 20a
Wires more $$, but for lighting runs you can have more lights on a circuit
I have almost 2 full rolls of 14-2 that I need to use
So I'll be using it up on my addition, other then that I'd rather run 12g
I used to run all 12g...when a roll was $29 :laughing:
Then I moved to this house & needed more & went to buy it & a roll was $129 :eek:

So I switched to using 14g for lights, the 15a breakers were here - I had spares
I had intended to go with 12g & 20a.....but I have enough 15a breakers already installed to cover all my lighting needs
 
#19 ·
Hmm how would a fire start on 14awg wire if the amp draw is not even close to what the wire is rated for? Even though it was on the improper breaker it was only drawing a couple amps. Did they just blame it on the wire because it's the only thing they saw that was wrong? I would almost suspect the light itself got too hot and burned or something. OR did it have an arc fault that caused a short and burned the wire before tripping the breaker?
 
#22 · (Edited)
I have a couple 20A circuits in my house and noticed they're all on 14/2 wire.
You already have the wiring in place.
Run 20A or 25A through it with two hair dryers and several incand. lamps and see if any section of the wire gets hot enough to ignite tissue paper.

Here's the touch test:
no burn ever at 42°C(108°F)
burned in 30 sec at 54°C(129°F)
5 sec at 60°C(140°F)
1 sec at 71°C(160°F)

The cable may take 15 mins to stabilize at its final high temp.
 
#25 ·
Hmm I'll have to try that. I can also test to see if my stab lok breakers actually trip like they should by increasing over 20amps. :p I don't have a blow dryer, but my 550 space heater, shop vac, and air compressor should probably do the job. Can then add smaller items like incad lights. I should get a killawatt, it would come in handy for a test like this.
 
#27 ·
I just ran a test on a 15 amp circuit, was more a "while I'm doing this" type thing. I had my air compressor going and my shop vac going on a single 15 amp circuit, that circuit has some lights as well. I was cleaning out a PC so I would just empty the compressor in single shots (small tank) and then wait for it to fill up and keep working, all while the shop vac remained on. I decided while I'm waiting for the tank to refill to plug my dewalt drill into the circuit and just keep turning it on/off sometimes leaving it on. I don't recall all the amperates off the top of my head but I totalled it and it came up to around 29 amps total! I touched the wire (before it feeds all 3 items) and it felt slightly warm but very hard to tell. I had to go to the other end of the circuit and touch it to see a difference and even then it was minimal. I did this for maybe about 15 minutes.

Now I'm not sure how much amps these devices actually pull off, maybe the ratings are more or less startup use or max use and maybe they only use half when in normal operation. Could this be? I'm just surprised I never tripped the 15 amp breaker. Then again, it is a stab lok... :eek:

Should I be worried and maybe test this further? This is kinda going away from the original question, but while I'm testing high loads...

I plan to upgrade this panel eventually though. It's a somewhat newer stab lok so don't think I need to be worried, at least I hope not.
 
#28 ·
I hesitated whether to reply to your post with repeating your post. (Since I don't (yet) know how to fraction a quote. (Shame on me.)) But since you make some major points about overloading circuits and about "Stab-Lok" panels/breakers, I'm re- quoting you, anyway! As I pointed out in another post (on this thread) that a particular fire that happened wasn't due to the slight, possible overload. Rather, the primary cause must have been a bad connection. IMHO a fairly small (few % of capacity) overload, occasionally, is not dangerous. But another part of your experiment surprises me. Because my experience in the past few years, working with FPE/Stab-lok panels showed just the opposite. They were very sensitive on circuit overloads. Their weak point was on responding to "Ground Faults" (Shorting to ground, a/o to Neutral). Another interesting point is, that the Oooold Federal breakers responded to Ground Faults very quickly, too. But those were "Bolt-ONs. BTW. They were one of the most popular & efficient brand of breakers some time ago. Only when the manufacturer took shortcuts in the production process (i.e. Using low-quality, corrosive materials) and subsequently attempting to fool the UL, is what led to their downfall and demise, after the multiple "Wrongful Death" and injury lawsuits.
 
#39 ·
I think I would setup a test 14-2 circuit that was not in the wall if I really wanted to test this

My 1st item would be a 1500watt heater running to use most of the 1800w
Then additional 100w light bulbs that could be plugged into a power strip to raise the wattage

I was never really worried about breakers tripping when they were supposed to
Until my I noticed water dripping out of my mom's panel
Water was coming from inside the feed wire sheathing into the panel
Never been so freekin scared as when I realized that
---standing there barefoot outside my basement bedroom in a puddle

Electrician replaced panel, main feed & all the breakers (maybe meter too)
He said some breakers were so rusted they probably would not have tripped
 
#40 · (Edited)
I think I would setup a test 14-2 circuit that was not in the wall if I really wanted to test this
I did this. The temp rise from 20A flowing through #14 Romex was hardly detectible with a thermistor embedded under the outer jacket.
A dryer outlet supplied the 20A and it took 15 minutes for the temp. to stabilize.

You can check breaker performance against their trip curves by drawing enough current to trip the CB in 10 secs or 100 secs, depending on your load.
You can also check the 1/2 cycle trip time by vaporizing a small gauge copper wire, but that is not for DIYer's.

Sultini, where ya' been? The place hasn't been the same without you! :laughing:

BTW, I heard Tesla wrecked a building in Chicago by spinning an eccentric flywheel at the building's resonant freq.
 
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