Long lighting circuit with ceiling fans

Reply

  #1  
Old 03-19-13, 07:42 AM
Member
Thread Starter
Join Date: Mar 2013
Posts: 10
Long lighting circuit with ceiling fans

One line summary: Is 13.75 amps on a 60 ft lighting circuit too much for 15amp/14ga ?

I'm rewiring the 2nd story of a 100 year old home because the K&T wiring has to be replaced. I read in a wiring book that the longest recommended length for a 15a 14g wire run is 73 feet. The 2nd store lighting circuit that I'm trying to figure out will have 6 light fixtures on it, 3 ceiling fans and 3 closet single bulb fixtures. If each fan has 4 100 watt bulbs and a motor that's 50 watts, that's 450 watts times 3 fans that's 1350 watts, add in 3 more 100 watt bulbs for the closet fixtures to get around 1650 watts, that's 13.75 amps.

The idea is pull wi
One line summary: Is 13.75 amps on a 60 ft lighting circuit too much for 15amp/14ga ?re up through the center of the house into the attic and branch off 3 wires from a junction box, each feeding a closet light and room light (ceiling fan) and a switch. This design runs close to 60 ft for the longest path from the attic junction box back to the panel.

The other option would be to wire everything individually from the attic JB (like s star pattern), but that would be 6 wires out of the box and one 1 in to the box. *A direct line from the JB to the switch and overhead lighting, and another direct line from the JB to the closet lighting, and so on would reduce the length to something like 50 ft.

My question is: this seems to be quite pushing the limits of 14 gauge 15 amp circuit. Should I run 12 gauge up to the attic and 14ga from the JB to the fixtures? What's wrong with just doing the whole lighting circuit 12ga/20a? I understand that mixing gauges can confuse people down the road, so clearly marking the smallest gauge on the branch would be done at the box if it was mixed 12 and 14.
 
Sponsored Links
  #2  
Old 03-19-13, 09:15 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,639
Should I run 12 gauge up to the attic and 14ga from the JB to the fixtures?
All wire on a 20amp breaker must be #12 (or larger).

What's wrong with just doing the whole lighting circuit 12ga/20a?
Nothing would be wrong with that. It is a good solution.

A third solution going back to your first idea would be to run a multiwire circuit off of either a 15 amp 240v breaker or two handle tied 15a, 120v breakers using 14-3 to an attic Jbox and then running two 14-2 cables. Each cable to half the lights. This would give the advantage of slightly easier to work with #14 wire.
 
  #3  
Old 03-19-13, 09:51 AM
Member
Thread Starter
Join Date: Mar 2013
Posts: 10
Should I run 12 gauge up to the attic and 14ga from the JB to the fixtures?
All wire on a 20amp breaker must be #12 (or larger).
For that solution I was thinking of keeping the 15 amp breaker, and use a 12ga feeder wire just to reduce the overall length of the circuit that is on 14. 12ga up to the attic as sort of a "trunk", then 14ga for ease of installation to all the luminaires and switches, thus reducing the overall length of the branch that is on 14ga by about 30 feet.

But, then as I added up the wattage estimates of 3 ceiling fans with 4 potentially 100 watt bulbs, it seemed to go over the 20% margin of a 15amp circuit. So then I'm thinking, I have 12ga up in the attic, why not just push it everywhere and bump the circuit up to 20A?

Actually, now that I think about it, there's 7 lights up there. The hallway/staircase light will also be on that. Even though I know not all lights and fans will be on simultaneously, it seems like a 20a lighting circuit makes sense in this situation.
 
  #4  
Old 03-19-13, 09:57 AM
Member
Thread Starter
Join Date: Mar 2013
Posts: 10
Also, is the consensus response to running 12ga everywhere regardless of 15A/20A over protection "it's your money, spend it how you want?"
 
  #5  
Old 03-19-13, 10:03 AM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 18,513
I find 12 ga a lot harder to work with than 14, I don't use it unless I'm on a 20 amp circuit. Also, it can cause confusion when seeing 12 ga wire, as most will assume that means it's on a 20 amp circuit.
 
  #6  
Old 03-19-13, 10:06 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,439
I wouldn't normally run #12 on a 15amp circuit unless it was a long run to a single device. Running a lot of #12 on a 15 amp breaker, as in your case, seems to be wasteful.
I'm not a fan of mixing wire sizes within a single circuit.

If I was in your position I would be running a 14-3 and splitting the circuit in two like Ray mentioned earlier. Less cost and the wiring is easier to work with.
 
  #7  
Old 03-19-13, 10:38 AM
Member
Thread Starter
Join Date: Mar 2013
Posts: 10
Can you do the 14/3 off of one of those dual 15 amps breakers (single pole, two switches) as long as the switches are physically connected (handle tied) or does that defeat the purpose?
 
  #8  
Old 03-19-13, 10:42 AM
Member
Thread Starter
Join Date: Mar 2013
Posts: 10
I wouldn't normally run #12 on a 15amp circuit unless it was a long run to a single device.
Well, I feel it's a fairly long run (60 ft) and why should I push the limits when it's brand new wiring (potentially 14 amps if all bulbs are 100 watts and all fans are on)?
 
  #9  
Old 03-19-13, 10:52 AM
Member
Thread Starter
Join Date: Mar 2013
Posts: 10
A third solution going back to your first idea would be to run a multiwire circuit off of either a 15 amp 240v breaker or two handle tied 15a, 120v breakers using 14-3 to an attic Jbox and then running two 14-2 cables. Each cable to half the lights. This would give the advantage of slightly easier to work with #14 wire.
If common and ground from the 14/3 are each used as neutral for the half of the lighting fixtues wouldn't the fan motors technically be "ungrounded" then? Either that or the neutral wire and ground wire from the 14/3 are doing double duty on 2 15 amps circuits.


UPDATE: i think i answered both my own questions. Using a dual flip 15A breaker would not allow the two hot wires to be on different "phases" of the 2 legs of the mains input. This would cause the neutral or ground wire to play double duty. Using some combination of breakers or a double pole breaker stops the two electrical phases from combining and overloading the neutral.
 
  #10  
Old 03-19-13, 11:36 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,639
Can you do the 14/3 off of one of those dual 15 amps breakers (single pole, two switches) as long as the switches are physically connected (handle tied) or does that defeat the purpose?
If you mean tandem no. One breaker on each of your 240v buses is requited. A tandem is both breakers on the same 240v side of the line.

UPDATE: i think i answered both my own questions. Using a dual flip 15A breaker would not allow the two hot wires to be on different "phases" of the 2 legs of the mains input.
That is correct.

This would cause the neutral or ground wire to play double duty.
In a proper multiwire circuit the neutral only carries the difference between the amps on each leg of the 240. Since neither of the 240's can exceed their amp rating the difference will always be at the amp rating or less. (15 Leg A- 0 leg B = 15)If both breakers are on the same 240 leg the current is additive and can exceed the amps of the breakers. Ground does not factor in. It only carries current in a fault situation.
 
  #11  
Old 03-19-13, 02:26 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
I'm rewiring the 2nd story of a 100 year old home because the K&T wiring has to be replaced. The 2nd store lighting circuit that I'm trying to figure out will have 6 light fixtures on it, 3 ceiling fans and 3 closet single bulb fixtures. If each fan has 4 100 watt bulbs and a motor that's 50 watts, that's 450 watts times 3 fans that's 1350 watts, add in 3 more 100 watt bulbs for the closet fixtures to get around 1650 watts, that's 13.75 amps.
Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG. A circuit protected at 15 amperes can safely supply up to 1,800 watts of non-continuous load or 1,440 watts of continuous load. A continuous load is defined as a load that is connected for more than 3 hours.

Your values for the lighting seem unusually high. I don't recall ever seeing a lighting adapter for a ceiling fan that had four lampholders rated at 100 watts each. 60 watts is usually the upper limit. Beyond that, 400 watts of incandescent lighting clumped together would almost certainly produce an overwhelming amount of glare. A 100 watt incandescent fixture in a closet would likely exceed the heat limits allowable in a closet, and fixtures mounted tight to the ceiling are almost never rated for lamps that are larger than 60 watts.

If we say that you have two 60 watt lamps in a pendant fixture in the stairwell, that would make a total of 17 lampholders on this circuit. If they're lamped (and rated) at 60 watts each, that's 1,020 watts total. Another 150 watts for the three fan motors brings the total to 1,170 watts.

I would wire it with a single 15 ampere circuit using 14-2/G cable.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'