Wiring entire house with #12AWG

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jeff48356

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Livonia, Michigan
I've seen a number of houses where the electricians wired the entire house with 12AWG, rather than using #14 for the lighting circuits. This makes NO sense to me at all why anyone would do that. Wiring the receptacle outlets with 12AWG is great, as long as they are separated from lighting. Then wire the lighting circuits with #14 wire, separate from any receptacles or other loads (other than smoke alarms and a doorbell).

The main problems with wiring lighting circuits with #12 are:
1) Extra cost for #12 cable versus #14
2) Extra difficulty in working with #12 vs. #14, especially in multiple-gang switch boxes containing lots of wires
3) Box-fill issues. The same number of #12 conductors will NOT fit into a box of a given size filled with #14 conductors.

In reference to #3 above: For example, if wiring a lighting circuit, and using a 2-gang blue Carlon switch box, it can hold 16 #14 conductors. Let's say the circuit design calls for four 14/2 cables and one 14-3 cable in the box. This would add up to 16. Therefore, the same design could NOT be implemented using #12 wiring without using a larger size box.
 
Some of those that do that probably also do a lot of non residential work and often have specifications of 20 amp circuits to nearly all 120 volt circuits, some may not even realize they can use a 15 amp circuit for power or lighting period.
 
jeff48356 said:
I've seen a number of houses where the electricians wired the entire house with 12AWG, rather than using #14 for the lighting circuits.
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I see that you are from Knoxville. In certain areas of Tennesee at one time #12AWG was all that was allowed. The same goes for areas around Atlanta.

Things do change and I think #14 is accepted most places but old habbits die hard.
 
Those who use 14 regularly for many of the circuits don't understand why others use 12.

Those who use 12 regularly for all the circuits don't understand why others use 14.

There is no right way. Both are acceptable. It's just another version of Coke v. Pepsi, Ford v. Chevy, Nikon v. Canon............
 
480sparky said:
Those who use 14 regularly for many of the circuits don't understand why others use 12.

Those who use 12 regularly for all the circuits don't understand why others use 14.

There is no right way. Both are acceptable. It's just another version of Coke v. Pepsi, Ford v. Chevy, Nikon v. Canon............
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:thumbsup:

This is an odd day but I both understand and agree with Ken 100%. :D
 
I use all #12 in my own house because I prefer all 20 amp circuits. If box fill is an issue I use a bigger box. Commercially we use mostly #10 for branch circuit home runs so #12 is a breeze. :cool:
 
growler said:
I see that you are from Knoxville. In certain areas of Tennesee at one time #12AWG was all that was allowed. The same goes for areas around Atlanta.

Things do change and I think #14 is accepted most places but old habbits die hard.
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I don't know where you are getting that Tn (at one time) only allowed #12 in certain areas. We have a state wide adoption and I've never seen that requirement accept on certain job specs. But certainly not from a code stand point.
 
The only argument I can see for number 12 is one or two maybe 3 less circuits when going by the bare minimum VA per foot. Other than that IMO I think its nothing more than a bragging right for whom ever makes the decision. Sure you get a tad less voltage drop, but in all honesty nothing in a resi draws 20amps or is effected by VD, and I personally despised working with #12- especially high hats and pancake boxes.
 
The Carlon blue boxes are the most popular in this area. When I enter a house wired with all #12
and Carlon boxes I know I have a 95% probability of a red tag on box fill.
As other have stated, it's a matter of preference but I'm certainly in the #14 for lighting camp for the reasons mentioned in post #1.

ps: Like LittleBill, I've never known an area in TN that had a restriction on #14 but there may have been a local rule + some of our inspectors make their own rules :)
 
infinity said:
I use all #12 in my own house because I prefer all 20 amp circuits. If box fill is an issue I use a bigger box. Commercially we use mostly #10 for branch circuit home runs so #12 is a breeze. :cool:
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Personally in all homes I've lived in I've pulled 14/3 and split wired everything when I had to do it. That is not to say you are wrong, we all have our own ways in belief, just the odd ball that I am :p
 
jeff48356 said:
I've seen a number of houses where the electricians wired the entire house with 12AWG, rather than using #14 for the lighting circuits. This makes NO sense to me at all why anyone would do that. Wiring the receptacle outlets with 12AWG is great, as long as they are separated from lighting. Then wire the lighting circuits with #14 wire, separate from any receptacles or other loads (other than smoke alarms and a doorbell).

The main problems with wiring lighting circuits with #12 are:
1) Extra cost for #12 cable versus #14
2) Extra difficulty in working with #12 vs. #14, especially in multiple-gang switch boxes containing lots of wires
3) Box-fill issues. The same number of #12 conductors will NOT fit into a box of a given size filled with #14 conductors.
Click to expand...

To be fair 12 doesn't cost that much more than 14. OTOH, if you are doing tract housing the cost does add up. I don't find 12 to be that much more difficult to work with- a big issue with it in residential is that a job will go a little slower b/c you can't backstab it (a plus there) if you use cheap devices-of course when you buy the spec grade stuff (something that does not happen with most residential) with pressure plates that argument is gone.....

There is no issue imo with putting and mixing a couple of bdrm ckts and lighting on 14 awg in a new house- the place will have a modern hvac system, so no space heaters/ window ACs. A reno without such a system is different- is that case putting a bdrm on its own 20a ckt (or at least putting a dedicated near the window(s), etc..) and doing the lights in 14 would be better.

Mainly, as alluded to above, its a belt and suspenders type of deal.
 
jeff48356 said:
.........1) Extra cost for #12 cable versus #14.........
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Only if you figure on running 12 instead of 14 in a 1:1 ratio. With 12, however, you can hook more outlets to a circuit, resulting in fewer circuits. This means fewer homeruns, less labor to install few homeruns, and fewer circuits needing those *(@)(&*$ expensive AFCIs.
 
Never seen a house here wired with all #12/20A branch circuits. MWBC are extremely rare in residential here too.

"augie47
The Carlon blue boxes are the most popular in this area. When I enter a house wired with all #12
and Carlon boxes I know I have a 95% probability of a red tag on box fill."

Yep. Box fill is often blown with #12 if there is more than 2 cables in the box. 3 #12 NM and a device is 6.75 + 4.5(3) = 20.25ci. I count the first cable w/ground as 3 wires, then 2 for each additional cable (since grounds are counted once) and the device (most boxes used here have no internal clamps to count). A 12/3 feed or switched receptacles blows even a 22ci box unless it's all daisy chained and nothing is jumped out of the box.
 
Here in nyc it's a very common practice to use #12 for the whole house, in fact it's a violation to use #14 for line voltage in NYC period

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nickelec said:
Here in nyc it's a very common practice to use #12 for the whole house, in fact it's a violation to use #14 for line voltage in NYC period

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That would maybe make sense in some buildings there- NYC is full of old apartment buildings and other mu housing (long runs possible, window acs, heaters if hvac is not working, insufficient and old etc). But a complete ban for ALL housing is unnecessary imo.
 
One reason you might want to standardize on #12, is if most of your circuits are 20A circuits that require it. If only an occasional circuit is a 15A circuit, you might as well just run #12 anyway. Less rolls of wire to inventory for the job.

If you have a choice between 15A and 20A circuits, there is an advantage to standardizing on 20A circuits for your general lighting and receptacles. More kVA on the same circuit, and thus less circuits in total. You can also use 15A receptacles on 20A circuits when there are multiple receptacles, because the receptacle is rated to supply 15A at the plug, and carry 20A through to the next receptacle. A 15A receptacle is also cheaper than a 20A receptacle.
 
user 100 said:
That would maybe make sense in some buildings there- NYC is full of old apartment buildings and other mu housing (long runs possible, window acs, heaters if hvac is not working, insufficient and old etc). But a complete ban for ALL housing is unnecessary imo.
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Agreed. As most of the things in NYC are unnecessary

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