Replies

1. 
   G.LaLonde | Jul 29, 1999 02:08am | #2

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   Larry, The difference in price between #12 & #14 NMC at our supplier right now is less than 2 cents a foot. If I was building a house like yours, I wouldn't put # 14 wire anywhere. It sounds like a large house with a lot of loads. You'll get many more loads per run of wire with the # 12 and leave your options open down the road. You will also get less voltage drop as Mike pointed out. I think it's only a matter of time before #14 wire is not allowed in new homes.

2. 
   Guest_ | Jul 29, 1999 03:41am | #3

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   Larry,

   I won't use 14 wire for anything anymore except temp lighting. Thats just my opinion and Mike is correct in everything he says. But G is also right. The cost difference is negligible and it's really not any harder to work with so the labor should be about the same too. I use 12 for everything just because I feel its the right thing to do, and if a future remodeler or homeowner wants to add load to an existing circuit they usually will have more latitude.

   Over building as usual,

   Richard Max

3. 
   ToolBear_ | Jul 29, 1999 12:46pm | #4

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   Larry,

   300 lights? A common split ranch?

   I ran some numbers on the ElectriCalc to see what the damage is: Assume 120V, a modest 10A load, and CU wire. To maintain a 3% voltage drop, you can run 14g for 60.24' and 12g for 95.53' How long are your home runs?

   In practice, for the Habitat duplexes we are doing, they get 12g for the outlets and 14g for the lights and fans. We even run 14/3 to the switch so they have the leg for a ceiling fan, should they desire to upgrade. The box is even rated for a fan.

   I looked at one custom house that had 400A of service and a lot of 14g Romex wiring.
   When the home runs go from front to back and up three floors, I would not be running 14g. Would have loved to see what the voltage was on the top floor, back, with a 1000VA load

   If you want to see real voltage drop in action, come to the Skagit County Habitat project. The farmer that donated the land (Very nice of him. Enough for a whole tract.) is also supplying construction power - via a very long run of 12g extension cords from his shop. Wonder why the connections are hot?

   TB

4. 
   Guest_ | Jul 30, 1999 11:19am | #5

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   Yeah, voltage drop is the big problem, but only as you approach 15 amps and/or long runs. Power dissipation grows (and voltage drops) as a function of current squared times resistance; so the slightly greater resistance of the thinner wire or longer runs is only significant on moderately to heavily loaded circuits. Lights are less efficient at lower voltages but otherwise don't care. Other devices may be damaged by lowered voltage, and you may get dimming of the lights when a new load is switched on. So long as the wire is properly fused -- so that it's maximum ampacity is protected -- it's not going to catch fire or anything.

   I think 14 gauge is faster to work with, especially when pushing everything into a wall box, but have started using 12 for everything to avoid mistakes and allow for future changes. It is a nuisance having two kinds of wire around. it doesn't sound like your contractor is doing anything outrageous, unless the run length vs. amperage max. is being pushed. But I'd choose 12 ... esp. if I wasn't doing the installation!

1. 
   Guest_ | Jul 30, 1999 09:56pm | #6

   *One point I always make if using 14 wire anywhere in a circuit is to make sure that the wire that enters the load center is 14. That way nobody will come along and think that since the wire is 12 a 20a breaker is ok.

1. 
   Guest_ | Jul 30, 1999 10:54pm | #7

   *The thing is, I've occasionally wanted to make the initial long run to a box with 12 then have 14 to, say, a dozen light fixtures. I thought of writing on the NM jakcet, "Look, moron, this wire is connected to a 15 amp breaker for a good reason" but think Mike's rule is safest. Not that the person who would try uprating the circuit would probably notice gauge anyway.Question: I've noticed that 14 is "rated" for 20 amps, but the Code has limited it to 15 amps. Anyone know why? Voltage drop concerns?The 14-12 price difference may be laughable now, but when copper prices shoot up again someday it may not. It was copper prices that caused builders to move from copper to aluminum way back when (oops).

1. 
   Guest_ | Jul 30, 1999 11:18pm | #8

   *Not that it matters one bit to Larry's original question, but as an amateur who has re-wired only his own house and no one else's, I found 14 gauge wire significantly easier to work with, as Andrew said, especially when trying to stuff things into a box (always within Code limits). You might even wonder whether someone is more likely to make good connections with 14 gauge wire because it is so much friendlier. I found myself choosing to make more 14 gauge circuits rather than use 12 gauge with fewer and longer circuits. However, this might be totally a non-factor for people who do this for a living and have stronger hands and fingers.

1. 
   Guest_ | Jul 31, 1999 12:39am | #9

   *Thanks for all the well thought out advice. I spoke at length with the contractor this morning, and he has assured me that we have no more than 15 cans on any one load, these are Juno halogen fixtures with a integral transformer that only pull 1/2 amp each. He has placed 4 subpanels around the house to distribute the loads, so the length of runs will be minimal. As Mark has suggested, the main reason for using #14 is ease of trim out at the panels, and he has assured me that using this wire will not compromise the design or the function. I am satisfied and am going to stay with the #14. Thanks for all the great feedback.Larry

2. 
   Guest_ | Jul 31, 1999 06:26am | #10

   *That's exactly how I felt. After a while, however, I refused to use the spring-loaded back terminals any more (limited to 14 but shouldn't be there at all) and started using pliers to twist the wires after getting enough cracked callouses using my fingers. You get better at arranging and bending the wires so that the devices go in easily too, saving a lot of grief. I can see why pros may want to use 12 only, but it's not a matter of life or death. Now, making mistakes with electricity IS a matter or life or death!Larry, those subpanels give you a big break on voltage drop and energy waste too. They cut the resistance on their subcircuits by half or better. So what's the scope of this project anyway?

3. 
   Guest_ | Jul 31, 1999 07:28am | #11

   *As we've discussed here before, in Ontario we use #14 on 15 amp circs for all residential plug and light wiring, #12 on 20 amp circs for resistance heating, shop motors etc. Having just finished a rewire as part of a reno I'm doing, I was instantly reaquainted with why I HATE #12. Friggin stiff, unwieldy #*%#* and it costs more than a couple of cents a foot (can't say at the moment how much more).Spend a couple of hours stuffin boxes with #14, and then tie into some #12 and you'll soon see the difference.If nothing else your fingers will thank you!The comments above on voltage drop, length of runs, and size of loads is all pertinent of course.Lovin #14-pm

4. 
   Guest_ | Aug 06, 1999 07:19am | #12

   *You know what, Larry?As a contractor, I really appreciate your response. A little communication is all it took to see that your contractor was not just trying to save a buck and compromising your job. If more people would take the time to communicate like you did... homeowners would feel better about their homes and their contractors, and their contractors would be more willing to go the extra mile. Good job.RayT

5. 
   Guest_ | Aug 06, 1999 09:43am | #13

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   My contractor is using 12 guage wire for the outlets, but says that the ceiling cans and other lights are best served by 14 guage wire. Should I demand 12 guage on the whole project? This is a big job with 300 lights, 400 amp panel and lighting control system. Thanks.

   Larry

1. 
   Guest_ | Jul 28, 1999 11:06pm | #1

   *You can demand anything you want, but unless it is specified in the plans or contract, your contractor can demand you pay extra for it. #12 wire is required on 20a circuits. Using #12 for outlets makes sense, since 20a circuits are preferable for loads that are not especially predictable. They have long been required for the small appliance circuits in a house where loads may be high. With more and more new electrical applicances and equipment, using 20a for all outlets is a good idea. #14 wire can be used on 15a circuits. For lights and ceiling fans the load is very predictable and unlikely to change much. The total number of lights or the size of the service makes no difference in the wire size for individual circuits. 20a circuits would allow more lights to be put on one circuit, thus reducing flexibility of controll. There is nothing wrong with 15a circuits, and there is nothing wrong with #14 wire. #12 wire on a 15a circuit would normally be excessive.The exception to this last statement would be if you have an extremely long homerun of wire from the outlets/lights on a circuit to the load center where it originates. This could be delt with by either reducing the number of outlets on the circuit or increasing the wire size. What, you may ask, is an extremely long homerun?That will depend on the load, the nature of the load,as well as the distance. I would question anything over 50'. Somewhere along the line you will have to trust the judgement of your contractor.