installing additional garage light fixture

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  #1  
Old 10-03-07, 06:12 AM
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installing additional garage light fixture

hey all, great forum, been searching a bit but unable to find an answer to my specific question.

im attempting to install a new track lighting fixture in my garage. i have the typical one bulb socket fixture in the center. i want the track lighting fixture off to one side. i purchased some nomex cable (includes black, white, and bare copper ground wire), a new box and the track lighting fixture.

the bulb socket fixture has only a black and white wire connected with the ground hanging free (coming out of a nomex cable). its operated by a switch on the wall. next to where these wires attach to the fixture itself i see additional screws (one for each) i presume for hooking up a parallel circuit?

what i want to do is use these additional screws (by attaching the new cable black to black screw, white to white screw, and ground to ground using a wire nut) and run the new wiring to the new location for the track light. the track light will have 3-5 75W bulbs on its track. is this ok to do?

ive done some basic car electronic/stereo stuff, but am new to this home wiring stuff. it seems pretty straightforward but i want to be sure im doing things the right way. thanks for any help.
 
  #2  
Old 10-03-07, 06:42 AM
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You plan sounds fine.
The cable is ROMEX or NM-B not nomex. Nomex is material for racing fire suits.
 
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Old 10-03-07, 05:11 PM
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right not nomex, dont know why i thought that. thanks!
 
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Old 10-03-07, 06:32 PM
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One additional comment. The bare ground wire that is "hanging free" at the light fixture is not needed for the light fixture. This is because the light fixture is plastic or porcelain. This fine if the junction box is plastic. However, if the junction box is metal, the ground wire should be connected to the box.

Since you are extending the circuit, you should connect the ground to the box, if the box is metal. You can do this with a pigtail from your wire nut to the ground screw in the back of the box (which you may need to install), or you can buy a special wire nut that allows one bare wire to extend through the wire nut. This bare wire is then connected to the ground nut in the back of the box.

By the way, nomex is also used in firefighter turnout gear and in firefighter uniforms (at least in New York, where required by law).
 
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Old 10-04-07, 06:16 AM
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thanks racraft. the original fixture and box is plastic (where the ground is hanging loose), but the new track light housing is metal, so i will ground the track light to the original ground wire and use a new plastic box for the track light as well. correct?

also, being new to home electrics, can i extend this circuit indefinitely, i.e. is there a limit to how many fixtures i can run off of the original in this parallel fashion?
 
  #6  
Old 10-04-07, 06:23 AM
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You have not posted a location. In Canada the limit is 12 outlets(receptacles and light fixture) per circuit.
 
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Old 10-04-07, 06:40 AM
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In the US there is no physical limit to how many lights or receptacles can be on a circuit. There are location limits (such as you can't have bathroom receptacles on the same circuit as hallway lights, but limits on the number of receptacles and lights.

However, there are limits on the amount of power a circuit can provide. A 15 amp circuit can only provide 15 amps. A 20 amp circuit can only provide 20 amps. When you exceed that limit, you trip the circuit breaker or blow the fuse.

With any circuit you have to determine the load already on the circuit and the load you plan to add. For lights, you can use the circuit that current = watts / voltage. Use 120 for the voltage. So if you have four 75 watt bulbs (a total of 300 watts), you will need 300 / 120 or 2.5 amps. If your 15 amp circuit is already loaded at 13 amps, then adding 2.5 amps will put you over the top.

Bottom line, know what is on each circuit and plan carefully if you want to extend a circuit. Use the maximum wattage light bulb amount in your calculations.

Note that I am simplifying many things. There are rules about only continuous loads and about loading a circuit to 80 percent of it's capacity that I am explicitly not talking about.
 
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Old 10-04-07, 09:19 AM
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Adding light fixture to garage

OK. If I understand your question, you are concerned about adding a fixture to the existing circuit that serves the overhead light installed in the garage. Is that correct?

First I am not an electrician nor am I an authority on the NEC Code. That said, here are my suggestions:

Determine the amount of power that is currentley used by the existing circuit. Determine the amount of power used by the new fixture. If it is within the limit of amperage supplied by the breaker, If it is to high, then you have other choices to make.

If the breaker is a 15 Amp breaker, you are limited to 15 Amps of current. Its not the number of loads on the line, it is the total current drawn by each load.

I would start by pigtailing a #12/2 cable to the wiring at the lamp. Then run this extension over to the new fixture's junction box. Connect all ground wires together. if you are planning to have a wall switch operate the light independent of the existing lamp, then you need to run a switch loop to the switch and back. Again use 12/2 cable, Connect the white in the switch loop to the black on the supply cable. Place small wrap of black tape around both ends of the white switch wire to signify that the white wire is now a load carrying voltage. Connect the other end of the white end to the switch. Connect the black from the switch loop to the other terminal of the switch. And the other end of the black to the black of the fixture. Connect the two white together.
 
 

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