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05451874 (banned)
join:2012-01-18
Worcester, MA

05451874 (banned) to Fronkman

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Re: is 12/2 really necessary?

When you buy 1000' of romex the difference is only like 17.5% more for 12/2 vs. 14/2. You're looking at like $285 for 12/2 vs. $235 for 14/2. I can't imagine that $50 is going to make much difference in the grand scope of things. If money is that tight there are other issues that need to be addressed.

DarkLogix
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join:2008-10-23
Baytown, TX

DarkLogix

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said by 05451874:

When you buy 1000' of romex the difference is only like 17.5% more for 12/2 vs. 14/2. You're looking at like $285 for 12/2 vs. $235 for 14/2. I can't imagine that $50 is going to make much difference in the grand scope of things. If money is that tight there are other issues that need to be addressed.

Exacly if money is that tight then you need to step back and wait till a later date for this project.

Fronkman
An Apple a day keeps the doctor away
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join:2003-06-23
Saint Louis, MO

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1000 feet of 14/2 is $185 at home depot, 1000 feet of 12/2 is $282, a 35% difference. it is not an issue of how tight money is, it is an issue of waste.

i am remodeling an entire 3500 sqft house using only the labor of myself, my wife and my dad. we are doing this because we can do as good of a job as most (but maybe not all) contractors and do it for substantially less money. this means we will have more money to buy nicer appliances, better looking tile, light fixtures, etc.

i don't want to waste this advantage by overpaying by 35% on materials for no measurable gain. what i am asking is for someone to convince me that using cable that is over NEC-specs (12/2 vs. 14/2) provides me with some tangible benefit.

currently, i remain unconvinced and i am NOT pulling 8/2 through plaster walls.

mattmag

join:2000-04-09
NW Illinois

2 recommendations

mattmag



The way I see it is you have two replies to choose from here, and the rest is hypothetical fluff...
said by nunya:

Normally (in our neck of the woods), 14/2 (15A) is used for the general purpose and lighting circuits.

14/2 is just fine. Keep in mind that you'll wind up with more circuits. My "rule of thumb" is 10 receptacles on a 20A circuit, and 7 receptacles on a 15A circuit. I've done it this way "ever since". I don't like callbacks, and I don't get callbacks.
There is no set number in the code for residential. You could put 547 receptacles on a single circuit, and it would still be compliant.

12/2 is just a bit more difficult to work with. 14/2 is just right. So, there's also a time savings.

If I get a situation, such as a long string where it would be silly to run two circuits, I'll go ahead and run 12/2.

I have mostly 15A circuits in my own home, and I'm not the least bit concerned about it.

You'd better cross your t's and dot your i's though. Both the city and county are cracking down HARD on homeowners doing unpermitted work. All it takes is one nosy neighbor to make a phone call.

And
said by whizkid3:

Sure, it will not get as hot. Might as well use 10 gauge. And if you want to feel safer, then you might as well use 8 gauge or even 6 gauge. But using 14 AWG on 15 amp circuits is as safe as it possibly needs to be.

As far as safety goes - there is absolutely no reason to use 12 AWG on 15A circuits, unless you want to protect yourself against some jackass who could come in later, and illegally and dangerously change out the 15A over-current protection for 20A. And if you're going to do that; you might as well just use 20A breaker to begin with. (Wiring with 12AWG and not using 20A breaker is just asinine to begin with.) You can trust me, or nunya, or anyone else on this. You're not gaining any safety. Any author who strongly encourages using 12 AWG wire on a 15A circuit for this reason, is mistaken, and likely has little real professional experience.

That being said, there are non-safety related pro's and con's to the use of both gauges. Being able to 'upgrade to 20A breakers in the future' is not one of them. It would be downright stupid to run the wiring using 20A now; buy 15A breakers now; and then pay again to buy 20A breakers later - when you could have put the 20A breakers in in the first place and saved money.

I prefer 20A wire for receptacle circuits. You are less likely to discover later that you need more receptacle circuits because your existing ones are overloaded. I prefer 15A for residential lighting circuits, primarily because its easier to wire and I like to break my lighting circuits with more switching, dimming, etc. It seems to work out better. Of course, if I have more than 1440 volt-amps (watts) of lighting on a circuit, I will use a 20A circuit.

In your case, I would recommend 20A circuits (wire and breakers) for the receptacles; especially if you were considering 12 AWG wire to begin with. Size the lighting circuits for their loads.

Two knowledgeable professionals, with two viewpoints to consider. Ponder their information and make your own educated decision.

alkizmo
join:2007-06-25
Pierrefonds, QC

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1000 feet is way too much, he'll be not only equating money by using 12awg for 15a circuits, but also waisting money on what could turn out to be 300 feet left over.

Anywho I can understand him on trying to not spend money on something that most likely won't benefit him. You guys are seeing the wiring as THE whole project. For him it is only a small part of the project. If he takes on the attitude of buying things that are more expensive just "what if" for his whole project, then he'll be spending a few hundred dollars on MANY parts of the project totaling a few thousand dollars over budget. Bigger plumbing pipes, thicker tiles, etc. Where to stop?

sk1939
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Frederick, MD
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sk1939 to Fronkman

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True, except that wire runs through walls at some point, past/through insulation. I also regularly de-rate my outlets just to have a margin of error. An outlet with 15A going through it at all times on a 15A circuit has a nice, explosive, failure.

The only real gain would be the added value when you re-sell your house, the new owners I"m sure would appreciate it.

Another thing you could do is run 2 14/2 wires to each outlet, break the metal tabs on the receptacle, and make it so the top and bottom outlets are on different circuits.

Diagram as follows:



Or you could also use a MWBC (mutiple wire branch circuit)


DarkLogix
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said by sk1939:

The only real gain would be the added value when you re-sell your house, the new owners I"m sure would appreciate it.

yep

I know when I one day buy a house it could for me atleast be a possible buying point as I wouldn't have to re-wire as much to make it met my overkill dreams

Fronkman
An Apple a day keeps the doctor away
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join:2003-06-23
Saint Louis, MO

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said by sk1939:

Another thing you could do is run 2 14/2 wires to each outlet, break the metal tabs on the receptacle, and make it so the top and bottom outlets are on different circuits.

i think i will pass, looks like more trouble than it is worth! (not to mention double the wiring costs)

thanks to everyone for all of their comments, i really appreciate the input. i think running 14/2 on 15A circuits makes the most sense for me. i will let you know how it is going once I actually start!

alkizmo
join:2007-06-25
Pierrefonds, QC

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said by DarkLogix:

said by sk1939:

The only real gain would be the added value when you re-sell your house, the new owners I"m sure would appreciate it.

yep

I know when I one day buy a house it could for me atleast be a possible buying point as I wouldn't have to re-wire as much to make it met my overkill dreams

Maybe if there are 2 identical houses right next to each others at the same price, then MAYBE MAYBE the 12AWG wiring will be the thing making the buyer decide between the two (And only if the buyers can appreciate that fact).

Otherwise, 12AWG wiring will NOT make a buyer pay more or chose your house over another.
said by Fronkman:

i think i will pass, looks like more trouble than it is worth! (not to mention double the wiring costs)

Reconsider it, it's not THAT complicated once you understand the logic behind the wiring diagram above. One thing for sure, you'll want outlets in your kitchen to have different circuits for top and bottom receptacles because of the kitchen appliances like the kettle, microwave, blender, toaster and toaster oven.
49528867 (banned)
join:2010-04-16
Fort Lauderdale, FL

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said by sk1939:

Another thing you could do is run 2 14/2 wires to each outlet, break the metal tabs on the receptacle, and make it so the top and bottom outlets are on different circuits.

And use a common 14 AWG for the neutral, are you nuts?

Um, how does that work, two hots protected at 15 amps each and a single 14 AWG neutral as the return?????

In addition have you ever seen the damage a open neutral can do to appliances if the hots are from two separate feeds providing 240 hot to hot?

Piss poor idea.

Wayne
49528867

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said by sk1939:

An outlet with 15A going through it at all times on a 15A circuit has a nice, explosive, failure.

Sorry, but that is bull crap...

Wayne

sk1939
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Frederick, MD
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You do know that's how MWBC are often run right?

Yes. I'm not saying it's the best idea, but it's been done. The way I did it (and what is good practice) was with two neutrals, rather a common neutral. It's how kitchen circuits used to be run back in the day, and I think it's a rather good idea.

I have, and it shouldn't happen if you break the tabs like your supposed to.

Not necessarily.
sk1939

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You mean other than the fact that the outlet in question blew out it's entire right side?
49528867 (banned)
join:2010-04-16
Fort Lauderdale, FL

49528867 (banned)

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said by sk1939:

I have scorch marks on my wall to prove it.

Yea right.

Wayne

sk1939
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Frederick, MD
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sk1939

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said by 49528867:

said by sk1939:

I have scorch marks on my wall to prove it.

Yea right.

Wayne

Don't be an ass.

Electrical fires caused by outlet failure can be quite volatile.

49528867 (banned)
join:2010-04-16
Fort Lauderdale, FL

49528867 (banned)

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said by sk1939:

Don't be an ass.

Electrical fires caused by outlet failure can be quite volatile.

Excuse me, you stated explosive and you had it happen, so knock off the Internet Googled crap and stick to what you have had "actual" experience with, ok.

Wayne

sk1939
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Frederick, MD
ARRIS SB8200
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sk1939

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said by 49528867:

Excuse me, you stated explosive and you had it happen, so knock off the Internet Googled crap and stick to what you have had "actual" experience with, ok.

Wayne

It's an exaggeration, but it was enough that I have scorch marks and 1/2 an outlet, the rest of it either blew apart or disintegrated upon touching it with a screwdriver.

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

garys_2k

Premium Member

Sounds like a backstab failure. Those can cause scorches and heat damage well below 15A. Backstabs are just crap in general.

cdru
Go Colts
MVM
join:2003-05-14
Fort Wayne, IN

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said by 49528867:

And use a common 14 AWG for the neutral, are you nuts?

Um, how does that work, two hots protected at 15 amps each and a single 14 AWG neutral as the return?????

Yup. Each hot is from a different leg. The return current can not exceed the amerage of the higher of either single leg. If both legs are used, the neutral only carries the difference.

In addition have you ever seen the damage a open neutral can do to appliances if the hots are from two separate feeds providing 240 hot to hot?

Have you ever seen a electrical device that required two different plugs into the same outlet? Yeah, me neither.

Dennis
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Algonquin, IL

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Discussion is good and are opinions when presented politely. I just ask we keep that all in mind here please.

Personally I'd go 12/2 just because I'd rather build the system to not need upgrading in the future, as opposed to building it for the perceived need today.

Keep in mind that's a general principle and not an expert opinion.
Expand your moderator at work

mackey
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join:2007-08-20

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Re: is 12/2 really necessary?

said by cdru:

In addition have you ever seen the damage a open neutral can do to appliances if the hots are from two separate feeds providing 240 hot to hot?

Have you ever seen a electrical device that required two different plugs into the same outlet? Yeah, me neither.

You completely missed his point. An open neutral on a MWBC affects ALL devices plugged in and can be very, very bad.

/M
nonymous (banned)
join:2003-09-08
Glendale, AZ

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I think someone may have mentioned this. But for specific things like home theater setups and say a computer room/ office/ whatever room you want to make sure you have enough power. Heck someone throws a coffee pot into the mix so do not have to walk to the kitchen.
Yes little things like TVs or computers or stereos do not individually overload a circuit. But if you have a larger shared office with multiple desks/ computers a nice laser printer a fax, then whatever else you have it adds up quick. Same with a home theater system. Just a TV a nice stereo a nice computer to send out the video to other rooms, a cable box a router a whatever it starts to add up.
A garage that is to be used for real manly hobbies is also a setup onto itself for power.

sk1939
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Frederick, MD
ARRIS SB8200
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said by mackey:

said by cdru:

In addition have you ever seen the damage a open neutral can do to appliances if the hots are from two separate feeds providing 240 hot to hot?

Have you ever seen a electrical device that required two different plugs into the same outlet? Yeah, me neither.

You completely missed his point. An open neutral on a MWBC affects ALL devices plugged in and can be very, very bad.

/M

If properly done, it's no different than an open neutral on any other outlet. Remember that the top and bottom parts of the outlet are completely SEPARATE. They are not connected together so that you have two hots to the same plug, rather two hots to two plugs joined together than share a neutral.

mackey
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join:2007-08-20

mackey

Premium Member

said by sk1939:

If properly done, it's no different than an open neutral on any other outlet. Remember that the top and bottom parts of the outlet are completely SEPARATE. They are not connected together so that you have two hots to the same plug, rather two hots to two plugs joined together than share a neutral.

I'm kinda confused. If you have both 2 hots AND 2 neutrals thereby making the 2 outlets completely separate then yes, it's as you say. However, if you have 2 hots on one side and a shared neutral on the other it is NOT "no different than an open neutral on any other outlet," it's an open neutral on a MWBC which probably means fried equipment unless both halves have the exact same load (very unlikely).

/M
Critsmcgee
join:2011-12-02

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said by Dennis:

Personally I'd go 12/2 just because I'd rather build the system to not need upgrading in the future, as opposed to building it for the perceived need today.

That's my thought as well. If your going to do something do it right the first time. While 14/2 will work today who knows if it will be good enough 5 or 10 years from now. It would be a nightmare to rewire all that 14/2 down the road and copper prices are only going up. The resale value between 14/2 and 12/2 is worth it alone. It wouldn't raise the actual price of the house like a lot of upgrades but it will make it that much more appealing to a new owner so it should sell faster. Either way hopefully you get it permitted and inspected. If you do the work poorly it could be a costly mistake.

whizkid3
MVM
join:2002-02-21
Queens, NY

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Sorry to say, but for some reason this thread is full of amateur opinion & mis-information. Unfortunately, the OP doesn't know who the professionals are here & who to trust. Little I can do about that.
said by 05451874:

Possibly but then why didn't his 12/2 ALSO melt? If 14/2 melts and 12/2 doesn't let's apply some logic instead of non-sense. An a/c unit could function fine on a 15a circuit as required yet when the compressor kicks on it can draw more then 15a's under some conditions.

Nonsense? Now who is trolling. Its obvious from your post that you don't understand this subject the way a professional does. You say a compressor can draw more than 15A under some conditions? No. It draws more than 15A under all conditions. Its a short term condition called in-rush and will not heat up the wire. Meeting the NEC code requirements for breaker size and wire size is more than good enough - its safe under all proper wiring installations - with a safety margin to boot. Circuit breakers are designed to work with their respective wire sizes, to trip under overload conditions, before the wire is damaged. This includes when the wires are grouped together as allowed, inside of thermal insulation. As quite a few people here have said there was something else wrong with the circuit you described; perhaps a poor connection or bad breaker.
said by 49528867:

More so when you consider the fact that 14 AWG copper can carry 20 amps until the cows come home without a problem.

Pretty much accurate. 14AWG wires can carry 20A without issue. However, the NEC limits 14AWG wiring to 15A, because of certain issues, mostly poor residential installation practices, where the crappy installer doesn't follow the other provisions in the NEC. (Think a few wires bundled together in an attic reaching 130 degrees F in the summertime. The NEC would require this to be derated. I have yet to see any typical homebuilder take that into account.)
said by Fronkman:

20A devices are 500% more expensive.

Then you are buying your materials in the wrong place. The cost of both 20A receptacles and breakers are usually the same price or just slightly more than 15A devices. And there is almost no need for 20A receptacles on 20A circuits, with the exception of a few appliances that require dedicated 20A circuits, anyway. Seriously, I think you should start to consider the use of a qualified electrician. Sorry to say, but your questions make me wonder how qualified you are to do the actual wiring.
said by 05451874:

Then why is 12 AWG required by code not just use 14 AWG for all 20 amp circuits...

Its not. 14AWG is permissible in quite a number of circuits, just not receptacles wired with type-NM cable.
said by sk1939:

Remember that for datacentres all circuits are de-rated; 15 amp is de-rated to 13A, 20 to 16A, 30A de-rated to 24A. It's not all that outlandish really, especially if your running multiple circuits in conduit, where you have heat dissipation to worry about.

There is no 'de-rating' as you discuss in data centers or anywhere else. You are mistakenly confusing the requirements for continuous vs. non-continuous loads. This is not de-rating the circuit. It also has absolutely nothing to do with the wire - just the breakers. Where thermal-magnetic breakers are used - which are not 100% rated for continuous loads - the load must be multiplied by 125% in the calculation. This is for the breaker to work properly. If you could buy a 100% rated breaker, the wire would not have to be increased. Individual wires in conduit have much better heat disipation than type-NM cable. Any multiple circuits have to have de-rating applied whether its in conduit or cable. This has nothing to do with the other points discussed here. Sorry, but there is nothing in your statement that is not wrong.

cdru
Go Colts
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Fort Wayne, IN

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said by mackey:

You completely missed his point. An open neutral on a MWBC affects ALL devices plugged in and can be very, very bad.

Yes I did miss his point. Or more accurately, misunderstood what he was getting at. You are correct. However MWBC are/were allowed (although AFCI breaker requirements make it expensive/impractical).
05451874 (banned)
join:2012-01-18
Worcester, MA

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said by whizkid3:

Sorry to say, but for some reason this thread is full of amateur opinion & mis-information. Unfortunately, the OP doesn't know who the professionals are here & who to trust. Little I can do about that.

Even if we did know who is who anyone can claim anything they want online. The only safe assumption is NO ONE here is a professional. I mean even the so called PRO's here are wrong all the time. A compressor can pull 12-13A when it starts normally but when dirty it pulls 15-17A. That just happened less then a year ago for me. It was verified by TWO licensed electricians as well. Once the coil was clean the compressor was back in the 12-13A range when it started. In this instance the compressor was hanging trying to kick over so it was sticking at that level until it popped the breaker which took a few minutes each time. I don't buy anyones professional opinions on the forums here without supporting info to back it up. No one has went as far as to prove anything either way just posting opinions.

Fronkman
An Apple a day keeps the doctor away
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Saint Louis, MO

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said by whizkid3:

Sorry to say, but for some reason this thread is full of amateur opinion & mis-information. Unfortunately, the OP doesn't know who the professionals are here & who to trust. Little I can do about that.

said by Fronkman:

20A devices are 500% more expensive.

Then you are buying your materials in the wrong place. The cost of both 20A receptacles and breakers are usually the same price or just slightly more than 15A devices. And there is almost no need for 20A receptacles on 20A circuits, with the exception of a few appliances that require dedicated 20A circuits, anyway. Seriously, I think you should start to consider the use of a qualified electrician. Sorry to say, but your questions make me wonder how qualified you are to do the actual wiring.

first of all, you haven't read my posts very clearly. i asked a specific question: is there a tangible, quantifiable benefit to wiring a 15A circuit with 12/2?

i NEVER said that i think that all outlets in a house NEED to have 20A receptacles on 20A breakers. the thread got a little off track and veered into the cost and utility of later upgrading a circuit wired with 12/2 to 20A receptacles and breakers. i quoted prices from home depot, not exactly an unusual or obtuse place to buy materials for home renovation. not everyone has access to wholesale prices, nor do they want to purchase 5000 feet of cable or 500 devices to get the wholesale price.

when you say that the prices are "usually" nearly the same for 15A and 20A devices, where do you shop?

i appreciate the input from many people on the safety of various wiring configurations. i also understand that there is not universal agreement on the best approach. the default position is from the NEC (plus/minus local code additions) but clearly many professionals and experienced people have practices that exceed the NEC.

i believe i am qualified to do this job and i don't buy your logic that buying materials from home depot automatically makes someone incapable of performing the work. i have an extensive background in science/physics and a lot of practical experience (growing up with a dad who completed 3 old house renovations himself as well as 5 years of habitat for humanity builds). this house has a pretty simple layout with almost no complexity. in fact, there is only one 3-way switch in the entire house, that is the limit of the complexity. furthermore, the work will be permitted and inspected.