A very basic question regarding wiring flourescent lights...

[Kewan Floyd]

I have a very basic question regarding fluorescent lights that I can’t seem to answer. I’ve attempted to use the SMC search engine, read through the home wiring book from B&D, and even tried searching the internet for this answer with no luck.

Is it better to wire 5 separate T8 4’ double bulb fluorescent fixtures by pig tailing the wires within the fixture or pig tailing the wires in a junction box outside the fixture? After pig tailing the wires using the correct method the wire would continue on to the next fixture and the method repeated. They will be controlled by one switch and running of one 15A circuit using 14/2. Is there a better way to go about this or am I on the right track?

For background I am converting a 22’x12’ area in my basement to a shop. I will be installing a sub panel and running the 5 fixtures from the sub panel on a 15amp dedicated circuit. I already have two single light fixtures with regular light bulbs in the shop that run off the main panel. I plan on tapping into that line from the main panel and adding a few fluorescent fixtures so that if the sub panel trips I will have plenty of “emergency” light.

I’m wiring up the outlets and lights myself but am hiring an electrician to check my work and to hook up the sub panel to the main panel. Thanks for your help.

[Bob Herpolsheimer]

I would wire a power supply cord to each fixture and then just put up nail-on boxes with a single receptacle in each box. Pig tail the receptacles on one circuit. This way you are able to repair/replace a fiture without having to shut down power. Double check me on your draw but you should be fine with the 15 amp circuit to run your lights.

Bob

[James Suzda]

Now I'm assuming that the power line is going to the switch. If this is correct, I'd run from the switch to the first light, then run a wire to the next light in the series and so on until power is supplied to all lamps. Plus I'd make the connections inside the fixture.
BTW, to help, here is a very good site to search for help on wiring, plumbing, and other good stuff:
http://www.selfhelpandmore.com/

[Matt Meiser]

I put a short plug in cord on each of mine and mounted a box in the ceiling at each one. The fixtures hang from chains. That makes it easy to take one down for service rather than work on a ladder.

[Ken Fitzgerald]

Kewan,

I have 11 8' 4 T-8 bulb fixtures in my shop. 3 rows of 3 fixtures and 1 row of 2 fixtures.

I placed a outlet box at the end of each row. Each row is controlled by it's own switch.

In each row, one 8' fixture is butted up to and connected to it's neighbor. the first fixture has a pig-tail that plugs into the outlet box. Internally fixtures are pigtailed using wire of high enough temp rating to withstand the heat of the ballast during operation.

1/2 of the lighting is on one circuit....the other 1/2 on another circuit. Should one breaker trip.....I'd still have 1/2 the lighting if it was turned on.

[Anthony Whitesell]

If the wires come out of the fixtures at the ends (rather than the center) then I would place the junction boxes between the fixtures and either hard wire or add a plug to the end of the pig tail. I would do as much work outside the fixture as possible. If it is inside the fixture and you decide to change something or the fixture needs to be changed out, you'll have to take the fixtures apart to get to the pigtails.

[Kewan Floyd]

Thanks for all the great (and quick) responses. Your responses bring up good points and help to clarify things for me. I like the idea of putting in outlets and running plug cords to each fixture so that it is easier to switch out bad fixtures or add/rearrange fixtures for better light. I think I will go that route.

I have found planning out the shop and working to get it ready is a lot of fun. Over the weekend I painted the walls white and that has already made a big difference in the light level. My next step is to run the wiring for the fixtures and outlets. As always, thanks for the help.

[Dan Oelke]

I have myself done short plug cords and outlets. But now that I think of it - how often have I moved any of those fixtures since I hung them? I would say in 10 years - never. So it might not be worth the extra hassle

[Chris Padilla]

I have various round boxes in my ceiling rafters in my garage and I just hardwired the 8' T8 fixtures right to them with some "nice looking" round, white wire. I have 4 rows (2 8' fixtures per row) and 4 switches. :)

[Ron Coleman]

If shop lights are hung from chains and can move around they should be wired with flex cable not solid building wire. An easy solution is install boxes and outlets and then connect the fixtures with cords. That's the typical industrial standard. If you have to service a fixture, it's easy to just unplug it and take it down without doing it in the dark.

I like to install pull chain switches on each fixture so I can turn off the ones I don't want if I'm in the shop just puttering around at the bench in the evening.

[Kewan Floyd]

I got started with the lighting project last night and assembled and hung all the fixtures. Tonight I want to tackle the wiring but I had another follow up question. I have 50’ of 14/2 MC wire (this is the MC-THHN type with black, white, and green wires) that a neighbor gave to me. Since it was free I was going to use this for the lights.

Does code allow you to run MC from the ceiling to the light switch without conduit? This is in a basement with cinder block walls so the MC would be out in the open. I know some wire needs to be protected by conduit when potential damage can occur (like exposed wire on a wall leading to a switch) but I didn't know if MC qualified as acceptable protection.

I posted this question over at www.selfhelpforums.com (http://www.selfhelpforums.com/) but it looks like that forum isn’t as frequented as SMC. Thanks for the help.

[Rob Russell]

OK - do you mean the spiral-bound, metal encased cable?

[Kewan Floyd]

Rob - yes, this is the spiral bound metal enclased cable. It has individual THHN wires (black, white, green) encased by the spiral bound metal.

[Rob Russell]

For your installation, it looks like MC cable needs to be treated pretty much like NM cable. Article 330 covers the requirements specific to MC cable. Under Uses Not Permitted, the first thing listed is "Where subject to physical damage." [330.12(1)]

A simple way to accomplish what you want is to run the MC through the ceiling joists. When you get over to the point where you need to run down the wall, take a length of straight 2x4 (good luck finding that!) long enough to reach from the ceiling down to where you will mount the switch box. You might want to use pressure-treated for this. Route a groove down the middle of the 2x4 deep enough to take the MC cable - probably about 1/2" will do. Make the groove just deep enough so the MC cable is flush with the surface. Fasten the 2x4 to the cinder blocks (something like Tapcon screws would be fine). This does 2 things - it gives you an easy place to mount your switch box and by recessing the MC cable in the groove, that should suffice for "protecting it from damage". You can secure the MC cable to the 2x4 with normal cable staples. By not making the groove too deep, the MC cable won't flop around inside the groove under the staples.

If you want to be extra sure, call your local building inspector and ask if that meet installation meets their criteria for protecting the MC cable from damage.

Rob
Addy protocol: unlicensed, homeowner electrician

[Ron Coleman]

Ignore me, my brain isn't on yet this morning.

Ron

[Don Bullock]

I put a short plug in cord on each of mine and mounted a box in the ceiling at each one. The fixtures hang from chains. That makes it easy to take one down for service rather than work on a ladder.

I agree with Matt on this one. Having plugs on the lights and receptacles in the ceiling also allows for more flexibility in light placement than hard wired lights. Having different switches for groups of lights like Ken does is also a good idea, but it does add a lot to the cost due to the extra wire needed (Have you priced copper wire lately?:eek:)

[Kewan Floyd]

Thanks again guys for the help. Rob - good idea on the 2x4.

My first thought was to run the MC wire through EMT conduit. Are there any issues with this approach? From the light switch to the ceiling is only 35-40" so it would be a short run. My first thought was it would be ok...the MC wire has a ground wire so it isn't like the old armored cable that used the metal casing as a ground.

[Rob Russell]

You could use EMT to sleeve the MC. You'd also need to find way to properly ground the EMT. The 2x4 is probably easiser overall if your local AHJ approves it.

[Ben Cadotte]

You could use EMT to sleeve the MC. You'd also need to find way to properly ground the EMT. The 2x4 is probably easiser overall if your local AHJ approves it.

I believe you have to have 1 1/4" min in front of the wire?? I dont have my NEC book with me. But if you don't have that, you have to protect the wire with a metal cover. I would leave the 2x4 whole and just add 2 - 1/2" strips to it leaving a channel for the wire.

I am pretty sure its 1 1/4". :confused:

I bought the cheapo 4' fixtures from the Borg. They are actually very good fixtures. Electronic balasts and can use t-8 or t-12 bulbs. The electronic ballasts work great in the cold (my situation). They come with 5' cords already attached (just had to put the chains on, ready to go). So I installed outlet boxes in the ceiling joists. Every other electrical box skips past one to the next. That way I can light the whole shop with either circuit. I have 6 4' 2 bulb fixtures on each 15 amp circuit.

[Wilbur Pan]

My next step is to run the wiring for the fixtures and outlets.

If you're not too far into this project, I would get fluorescent fixtures that space the bulbs as far apart as possible. This will spread the light more evenly than the fixtures that run the two bulbs right next to each other.

I would also heavily consider doubling the number of outlets you're planning to install, especially 220V outlets.

You may not think that you'll need this many outlets, but you're probably wrong. DAMHIKT. ;)

[Matt Meiser]

Then double it again. :D

I replaced all the original single gang boxes with double in my shop. I still have places where that's not enough. Not that I'm using that much power, but for example at one spot I have my planer, bandsaw, the bandsaw's light, and my sander plugged in. No spares unless I unplug something, and then the cord falls behind the tools etc. Another spot has my phone, miter saw, and emergency light. Only one spare. Where my chargers and drill press are, there's no where near enough. The drill press takes 3 alone for the motor, light, and laser.

[Thom Sturgill]

Every other electrical box skips past one to the next. That way I can light the whole shop with either circuit. I have 6 4' 2 bulb fixtures on each 15 amp circuit.

If you ran BOTH circuits to a duplex receptacle at each light, and break out the little brass strip connecting the top and bottom, then you have maximum flexability with arranging which light turns on with which switch. Only costs a little extra for the wiring. Just be consistent as to which circuit is wired to the top and which to the bottom. It will save confusion down the road.

[Rob Russell]

I believe you have to have 1 1/4" min in front of the wire?? I dont have my NEC book with me. But if you don't have that, you have to protect the wire with a metal cover. I would leave the 2x4 whole and just add 2 - 1/2" strips to it leaving a channel for the wire.

I am pretty sure its 1 1/4". :confused:


I suspect that what you're thinking about is the depth that cables have to be buried from the edge of a framing member. When the cable is run through holes bored in the framing member, the edge of the hole closest to the "nearest edge" of the framing member must be at least 1 1/4" in. This is so, if sheetrock is installed on the face of the framing members, even with 1 5/8" sheetrock screws or nails, you've clearance to where the wiring would be.

The reason I say check with the AHJ on the 2x4 is because they would need to consider that an "approved method" for protecting the MC cable.

[Ben Cadotte]

If you ran BOTH circuits to a duplex receptacle at each light, and break out the little brass strip connecting the top and bottom, then you have maximum flexability with arranging which light turns on with which switch. Only costs a little extra for the wiring. Just be consistent as to which circuit is wired to the top and which to the bottom. It will save confusion down the road.

I thought about doing that. But was easier and less stuffing to do in the single gang boxes by just skipping over to the next one. Also adding some more specific lighting on a third circuit when I get some time. These will be lights for specific machines or areas.

[Rob Russell]

These will be lights for specific machines or areas.

If these are lights for "specific machines or areas", why not just do the receptacles in the ceiling and pull chains on the lights? It's simple and the shop isn't so large that I'd think pulling chains to turn on the lights would be easy enough.

[Roger Warford]

Just to be clear, does the NEC allow joining the wire inside the fixture? Specifically, it would be two two-conductor wires coming into the fixture, one from the service panel or switch, the other going on to the next fixture. There would be three three-conductor bundles connected together (hot, netrual, and ground). I'll dig through the NEC later, but thought someone might know the answer already and save me some digging! :)

[Roger Warford]

It does appear that the NEC will allow wiring mutliple fixtures together inside the fixture. I forget the exact citation, but it is in article 410. Only note is that the wiring must be rated for the appropriate temperature if it passess within 3 inches of the balast.