Best practice for wiring lights - 1 or multiple circuits

[jpcjguy]

Hi all,

So I bought a bunch of 4 ft LED lights: https://www.ledlightingwholesaleinc.com/E5SLB35D4-850-p/e5slb35d4-850.htm

I plan on having the lights on 3 switches - left area, center bay and right bay.
Being that they are only 35 watts each and I am running 14/2 duo wire (for dimming), technically I could probably run all of them on one 15A breaker. (conservatively 1500w for the wire divided by 35 watts per light equals 42 lights - and I have 36)

But should I split them on 2 or 3 breakers? That way if one pops, I am not in the dark. Or am I over thinking this? (like I do everything according to my wife)

 

[jh87]

I see no reason to put the lights on separate circuits assuming you’re not also putting receptacles on the same circuit. Once the lights are on you’re not going to suddenly overload the circuit like you might by plugging in too many things into the receptacles on a circuit.

 

[spudley]

I'm running two circuits for the unlikely circuit pop, mostly because I bought a thirty space box that I'll never get close to using up, and breakers are cheap.

I'm doing two switches, center lights on one and outside rows on the second. Also including outside lights on the center circuit, separate switch.

 

[jpcjguy]

Both good points - lights are on a dedicated circuit and most likely never be overloaded, but with my luck - it would pop and I have a 30 foot walk in the dark to the panel through the hazardous maze of parts, tools, quads, etc. that will probably be my normal - ha!

 

[aussieblake]

Switching the lights by bay is a good idea, I switched my shop by bay.

Have your heard of the 80% rule for breakers? What that means is this, most breakers are rated at 80% of their listed capacity, i.e 15 amp breaker @80%- 12 AMPS, 12 AMPS at 120 Volt is 1440 watts (aka VA, VOLT AMPS). I only use 20 AMP Breakers, only cost difference is the conductor #12 vs #14 for a 15 amp breaker.

I am not saying your installation won't work on a single breaker, but its right at the threshold of potentially not working. I would plan on Two circuits, makes any guess work go away.

If you have any other questions you might PM me.

 

[nadogail]

IMHO, there’s no one correct answer to this question. With almost no exception both of all answers to this question are reasonable.

You could also put a single low wattage LED, on a dedicated circuit, near the panel and exit doors and fire extinguisher. A few 8 watt LED lamps will draw an insignificant amount of current.

 

[pattenp]

........

Have your heard of the 80% rule for breakers? What that means is this, most breakers are rated at 80% of their listed capacity, i.e 15 amp breaker @80%- 12 AMPS, 12 AMPS at 120 Volt is 1440 watts (aka VA, VOLT AMPS). I only use 20 AMP Breakers, only cost difference is the conductor #12 vs #14 for a 15 amp breaker. ... . .

I don't know where you got this info from, but the 80% is a rule for continious loads on a circuit from the NEC and not a rated limit of a breaker.

 

[Kaizen]

I thought of the separation of lights for energy sake. Then calculated the cost and said forget it.
Also as lights are dedicated breaker not much besides a power outage will cause them to go out.
Would recommend a lighted switch at man and roll up doors. 3 way


Sent from my iPhone using Tapatalk

 

[Shiftless]

IMHO, there’s no one correct answer to this question. With almost no exception both of all answers to this question are reasonable.

You could also put a single low wattage LED, on a dedicated circuit, near the panel and exit doors and fire extinguisher. A few 8 watt LED lamps will draw an insignificant amount of current.

Separate low wattage “safety illumination” is a good idea but if it’s on a separate circuit with its own switch, the user has to switch that on when he switches on the main lights. If a guy didn’t hit both switches and the main lights fail, he is once again in the dark. That could be controlled by a sensor that only turns on the safety lights when it senses a lack of current in the main lighting circuit.

Maybe a better idea would be to have a battery powered emergency exit light in the garage just like in a commercial space.

For me, that’s just one of the many reasons I carry a small flashlight (AAA powered Fenix) on my keychain.

 

[vavet]

If I understand this correctly, you have
36 lights x 35 watts/light = 1260 watts
1260watts/120 volts = 10.5 amps

80% of 15 amp = 12 amps

I'm not an electrician by any means, but I think you're good.
I still recommend putting them on at least 2 circuits. All my lights are on the same switch. I had a friend come over to help me with drywalling the garage. I had half the lights down so we could work on that part. We finished for the day and he went home. i figured I'd hang lights in the area we finished and remove lights from the part we were doing the next day to make the most of the time that my friend was there and available to help - I was wiring/mounting lights in the dark. That was fun.

Another reason to have them on 2 breakers- mount a receptacle in the ceiling for a cord reel. You can run almost 9 amps off that cord reel then when you'd be limited to 4.5 if you had all the lights on that same circuit.

 

[laser3kw]

Whoops!
didn't read enough

 

[Noltz]

I always like separation where space permits, but I don't think I'd wire them on separate breakers myself. Definitely on separate switches. And I'd spend the $50 and get an emergency light (the kind that pops on if the power goes out, runs on a battery). Add an outlet up high.

 

[ezzzzzzz]

I like zones. It's energy efficient if you only need lighting in a certain area vs illuminating the whole garage. This comes into play on cloudly days and dusk/dawn. At night I'm lit up like a football stadium. The extra effort and cost is justified to me.

 

[jpcjguy]

Thanks all. I think I might do 2 breakers. One for the bay (16 lights) and then one for the lights under the attic trusses (still 2 switches - splitting that area in half).
What stinks is the high dollar of the toggle 0-10v dimmer switch! Not a lot of options in the traditional toggle style....sigh...
https://www.bulbs.com/product/TSD4FBL3PTC?cm_mmc=GooglePLA-_-Nonbrand-_-9997527528-_-shopping&affID=6&gclid=Cj0KCQiAwf39BRCCARIsALXWETxHYVQEpeiVChpDrLzFAsoDeYbwefyT6XIp1oAvTw3ZXDXH0ARZsCAaAt4BEALw_wcB

 

[wyliesdiesels]

Switching the lights by bay is a good idea, I switched my shop by bay.

Have your heard of the 80% rule for breakers? What that means is this, most breakers are rated at 80% of their listed capacity, i.e 15 amp breaker @80%- 12 AMPS, 12 AMPS at 120 Volt is 1440 watts (aka VA, VOLT AMPS). I only use 20 AMP Breakers, only cost difference is the conductor #12 vs #14 for a 15 amp breaker.

I am not saying your installation won't work on a single breaker, but its right at the threshold of potentially not working. I would plan on Two circuits, makes any guess work go away.

If you have any other questions you might PM me.

this is totally incorrect. It is a myth that wont die. Breakers are rated for 100% of their capacity and do not have an 80% limit. The 80% rule applies to continuous loads and the wire for the circuit.

For example, a motor circuit requires wire that is rated for 125% of the FLC table current

 

[Crazyjake8493]

I would say there's really no reason to have multiple lighting circuits if one circuit is sufficient for your lighting load. A tripped breaker on a dedicated lighting circuit would be highly unlikely. Put all the lights on a dedicated lighting circuit, and put different bays on different switches if you want control over various areas.

 

[u2slow]

2 lighting circuits for me. One #14 MWBC. I try to load them evenly for minimal voltage fluctuations as I use some hungry 120V tools at times.

Lighting is never finished for me. Always changing. Not fully LED yet, so more loading. 2 circuits gives a lot of flexibility.

 

[ezzzzzzz]

I have only one breaker for my interior lighting. It feeds four switches for zoning. There is separate ambient lighting in the overhead and bathroom. I ran dimmer wiring for the high bays but decided I liked the level of lighting so didn't install dimmers. The low bay is the same situation so I never ran the dimmer wiring at all. The footcandle readings are probably 60 to 100 depending on the meter position. When looking at dimmers I considered Lutron Pico remote dimmers because I hadn't run dimmer wires to the switch locations inside the wall. They aren't cheap but work very well.

 

[PCustoms]

2 lighting circuits for me. One #14 MWBC. I try to load them evenly for minimal voltage fluctuations as I use some hungry 120V tools at times

Don't you loose the ”benifit” of 2 circuits if you wired MWBC?


I have 1 circuit split into 3 banks for my overheads. I also have a 2nd circuit that has a few basic bulbs, enough lighting to get through the garage and outside or up the stairs. This is on an occupancy sensor.

 

[u2slow]

Don't you loose the ”benifit” of 2 circuits if you wired MWBC?

How do you figure?

 

[PCustoms]

How do you figure?

Don't both breakers trip simultaneously?

 

[wyliesdiesels]

Don't you loose the ”benifit” of 2 circuits if you wired MWBC?

I have 1 circuit split into 3 banks for my overheads. I also have a 2nd circuit that has a few basic bulbs, enough lighting to get through the garage and outside or up the stairs. This is on an occupancy sensor.

Don't both breakers trip simultaneously?

Depends on the breaker/handle style

some breaker tie clips only trip one breaker despite being tied to both breaker handles.

obviously a DP SQ D with only one handle would trip both sides....

 

[alfredeneuman]

some breaker tie clips only trip one breaker despite being tied to both breaker handles.

Then they're faulty

 

[wyliesdiesels]

Then they're faulty

not necessarily. the handle tie is only for making sure both circuits are shut off simultaneously for circuit work NOT for overload tripping.

one can push down on the center of the tie and it should shut off both handles.

I have seen cases where the movement of a handle, during an overload/trip condition, is not enough to cycle the opposing handle its tied to. Furthermore, the handle is not even required to move in order for the breaker to trip. (think of handle lock-ons for fire alarm circuits)

 

[u2slow]

Don't both breakers trip simultaneously?

No tie bar; separate 1-pole breakers for me. I do things my way. You may do things your way

 

[alfredeneuman]

not necessarily. the handle tie is only for making sure both circuits are shut off simultaneously for circuit work NOT for overload tripping.

On second thought I agree!

 

[wyliesdiesels]

No tie bar; separate 1-pole breakers for me. I do things my way. You may do things your way

oh you code breaker!

 

[u2slow]

oh you code breaker!

Standard practice really... its allowed under CEC 14-010(b)... lighting and non-split receptacle circuits.