Question about wiring a circuit for fans/lights

[ACDNate]

Planning a circuit and wanted to run it by someone. Lights and fan on one circuit.

6 fixtures with 6 32w T8 bulbs
3 fixtures with 4 32w T8 bulbs
48x 32w bulbs = 1536 watts total
1536w/120 volts = 12.8Amps Lets call it 13amps

3 ceiling fans that draw .9amp each. = 3amps.

with a 20amp breaker I'll have 4 free amps, well within the 80% rule.

Am i thinking this out correctly?

Also on the ceiling fans. I bought a controller for them. Wiring Diagram attached.

My thought is that i'll have a MC cable 12/2(with ground) feeding the circuit to the 3 gang switch box. That will power both light switches (6 on one, other 3 on the other).

Power will feed to the controller as well. My thought was to ground the controller and the fans at each box. I want to use MC cable 14/3(with insulated ground) to provide my 4 wires from switch to the first fan and on down the chain to the remaining fans. Since the insulated ground will not be used as a ground, i'll mark it with tape at the exposed ends.

Will that work for my install?

Anybody make a 14/4 mc cable?

 

[n8n]

you can't mix wire sizes on a circuit, if you start with 12/2 you need to keep it 12AWG the whole way. This is in the NEC, I'm not trying to be a jerk just telling you what it says. Not sure if there is an exception for your situation where the wiring is run from a dedicated controller to the fan. I would research. If the controller includes a 15A or less fuse or breaker though then that should be OK.

I do not believe that you can relabel a green ground wire. Only whites and blacks.

Pretty sure there is 14/4 Romex and MC both available. Will become more common as now switch legs are required to have neutrals present by latest code. You could also use Greenfield and THHN to accomplish the same thing. If you bought 14/4 it would be 14/4 not counting the ground so you're still good there. (if you use greenfield/THHN you probably would be required to include a ground wire as well)

If you use a 20A ckt and 12AWG pay attention to box size and wire fill.

 

[ACDNate]

Ah gotcha. After reading it, i feel like i should have known that I can't change sizes on the circuit. I'll have to do some hunting to see if I can find some MC in 12/4 locally.

I'll be going with deep boxes throughout to hopefully not get too close on wire fill. May grab a pack of the slide in connections for the 3 gang to save some extra space with all that will be going on in it.

Thanks

you can't mix wire sizes on a circuit, if you start with 12/2 you need to keep it 12AWG the whole way. This is in the NEC, I'm not trying to be a jerk just telling you what it says. Not sure if there is an exception for your situation where the wiring is run from a dedicated controller to the fan. I would research. If the controller includes a 15A or less fuse or breaker though then that should be OK.

I do not believe that you can relabel a green ground wire. Only whites and blacks.

Pretty sure there is 14/4 Romex and MC both available. Will become more common as now switch legs are required to have neutrals present by latest code. You could also use Greenfield and THHN to accomplish the same thing. If you bought 14/4 it would be 14/4 not counting the ground so you're still good there. (if you use greenfield/THHN you probably would be required to include a ground wire as well)

If you use a 20A ckt and 12AWG pay attention to box size and wire fill.

 

[pattenp]

What NEC prohibits the mixing of wire sizes in a circuit?

you can't mix wire sizes on a circuit, if you start with 12/2 you need to keep it 12AWG the whole way. This is in the NEC, I'm not trying to be a jerk just telling you what it says. Not sure if there is an exception for your situation where the wiring is run from a dedicated controller to the fan. I would research. If the controller includes a 15A or less fuse or breaker though then that should be OK.

I do not believe that you can relabel a green ground wire. Only whites and blacks.

Pretty sure there is 14/4 Romex and MC both available. Will become more common as now switch legs are required to have neutrals present by latest code. You could also use Greenfield and THHN to accomplish the same thing. If you bought 14/4 it would be 14/4 not counting the ground so you're still good there. (if you use greenfield/THHN you probably would be required to include a ground wire as well)

If you use a 20A ckt and 12AWG pay attention to box size and wire fill.

 

[Zeke]

What NEC prohibits the mixing of wire sizes in a circuit?

I think your point is that as long as you don't overprotect the circuit and use the breaker appropriate for the smaller sized wire it's OK.

That doesn't make it a good idea. Let's make that clear.

 

[Mustang51js]

You can use any size wire you want but must breaker it to the smallest wire.

 

[pattenp]

Yep.. I know you can mix wire sizes as long as the over protection is sized to the smallest amp capacity. I just wanted to know what the NEC section was that n8n was referring to.

I think your point is that as long as you don't overprotect the circuit and use the breaker appropriate for the smaller sized wire it's OK.

That doesn't make it a good idea. Let's make that clear.

 

[ACDNate]

Yep.. I know you can mix wire sizes as long as the over protection is sized to the smallest amp capacity. I just wanted to know what the NEC section was that n8n was referring to.

I could use the 14 ga but I am planning on 16 amps on the circuit with a 20amp breaker so I have to use 12ga. Either way good discussion and help

 

[ACDNate]

On a related but not improtant note.

Why would the manufacturer use the wire color scheme they chose on teh controller???

The fan motor color scheme matches 12/4 cable and makes more sense.

 

[Charles (in GA)]

How will those fan boxes get their ground if you are not going to carry a ground wire to them???

You are not allowed to remark a green wire for other uses, if I recall. You might consider conduit for the run instead of MC.

Personally, I would split that up into two circuits, or three. You are setting yourself up so that if you don't have enough light, you cannot add more to the circuit.

Charles

 

[ACDNate]

How will those fan boxes get their ground if you are not going to carry a ground wire to them???

You are not allowed to remark a green wire for other uses, if I recall. You might consider conduit for the run instead of MC.

Personally, I would split that up into two circuits, or three. You are setting yourself up so that if you don't have enough light, you cannot add more to the circuit.

Charles

Found some 12/4 at an electrical supplier not far from here. Going to go that route.

You may be right on splitting that circuit. Was trying to cut down on 70' +/- runs from the circuit breaker to the switch box.

Also leaves me thinking that most of my circuits are going to terminate closer to center of the building than to one end. Maybe I should push my breaker panel towards the center...

 

[ACDNate]

While i've got the attention of you knowledgeable experienced folks. How do I go about my exterior connections?

I'll be putting in some dusk/dawn lights on the exterior of the building. What's the best way to mount a box and ensure it stays dry?

Punch just wire through skin of building and secure box to exterior?

Is there a way to recess it like a standard wall box in drywall?

 

[n8n]

Found some 12/4 at an electrical supplier not far from here. Going to go that route.

You may be right on splitting that circuit. Was trying to cut down on 70' +/- runs from the circuit breaker to the switch box.

Also leaves me thinking that most of my circuits are going to terminate closer to center of the building than to one end. Maybe I should push my breaker panel towards the center...

If you split into two circuits, if there's no requirement for them to be GFCI protected you could use an Edison circuit for the homerun to where they split. This will only give you some of the advantages however as you'd then have to use a double pole breaker, but you'd only have to run 12/3 or 14/3 instead of two x/2s.

I believe there are double pole GFCI breakers available as well, if you like the Edison circuit idea, but they are somewhat spendy.

 

[ACDNate]

If you split into two circuits, if there's no requirement for them to be GFCI protected you could use an Edison circuit for the homerun to where they split. This will only give you some of the advantages however as you'd then have to use a double pole breaker, but you'd only have to run 12/3 or 14/3 instead of two x/2s.

I believe there are double pole GFCI breakers available as well, if you like the Edison circuit idea, but they are somewhat spendy.

Dummy here and not quick on the industry terms.

Edison Circuit?

 

[nehog]

...
6 fixtures with 6 32w T8 bulbs
3 fixtures with 4 32w T8 bulbs
48x 32w bulbs = 1536 watts total...

Nope, you don't compute power using bulb, the current is shown on the ballast. This is because the ballast/bulb combination is not 100% efficient, but actually they are perhaps 80% efficient. (T5 is more efficient, T12 less.) I'd use 40 watts per bulb, giving 1920 watts (approximately.) That's about 16 amps. Add the fans, and you're at 19 amps minimum.

 

[ACDNate]

Nope, you don't compute power using bulb, the current is shown on the ballast. This is because the ballast/bulb combination is not 100% efficient, but actually they are perhaps 80% efficient. (T5 is more efficient, T12 less.) I'd use 40 watts per bulb, giving 1920 watts (approximately.) That's about 16 amps. Add the fans, and you're at 19 amps minimum.

Ah gotcha. Didn't think about the ballast draw. That settles that. Going to split the circuit.

Probably put the lights on one, that will allow me to split the fans, some exterior LED lights and maybe an exterior GFCI outlet off to another.

 

[Charles (in GA)]

The Edison circuit idea would be good, considering this is a long run from breaker to switches.

Edison circuit is technically known as a Multi Wire Branch Circuit (MWBC) which uses a double pole breaker, thus the opposing bus's of the circuit panel, to power a circuit, but share the neutral. Alternating current allows this to happen without overloading the neutral. You install the DP circuit breaker and then run 12/3 w/grd to the switch box. the neutral is pigtailed to all runs, and the two hots are used to power the lights and fans in whatever way you want. I would put the fans and the 3 ea 4 bulb fixtures on one of the hots, and the 6 ea 6 bulb fixtures on the other hot. This will split the loads much more evenly. The sticker on the ballasts will tell you how much current is consumed total by the fixture. Electronic ballasts are about 95% or so efficient, but there are still losses in the ballasts, so you cannot use bulb wattages alone.

Charles

 

[ACDNate]

Long weekend in the shop.

I ended up putting the 6 high bay (6 T8 32w bulbs ea) and two exterior 33w LED lights on one circuit. That gives me about 13amps on the circuit. Room for another couple bulbs if I find it necessary.

I put the 3 fans and 3 4bulb fixtures on another circuit. Around 8 amps, again room to extend that circuit.