Extending a circuit/drawing power from a light

18 years ago

Hi,

I have a single fan fixture in a room that I would like to split into two fixtures--one for a light and one for a fan. The wiring to this room comes from an earlier junction box straight to the fan fixture in the ceiling. The light switch wiring for the fan is connected at the box where the fan is and goes down to the wall. Based on what I see, I have three questions.

1. I want to run a line from that light fixture box about three feet away to another new ceiling box, then run a line from the new ceiling box down the wall for a switch. Is that acceptable?

2. The wiring to the original light fixture is older and does not have a ground wire. The new wiring to make the new light fixture and new switch does have a grund wire. Does this matter?

3. I would have assumed a straightforward "white to white, black to black" set of connections. HOWEVER, the older, fixture where the fan is appears to have at least one set of white and black wires crossed. That fixture is currently disconnected and it might be that the crossed black and white wires together went with the black into the fan? Am I in over my head?

Thanks,

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Comments (8)

asak9
18 years ago
1. Yes, that will work
2. Doesnt matter. Just be aware that you wont have a ground even if you connect the ground wire at the switch.
3. I am guessing you have a total of four individual wires at the fan (two 2 wire cables) and two at the wall switch (one 2 wire cable). The black and white wires spliced together would be the hot coming into the box and going down to the switch on the white. When you turn the switch on the power goes back to the fan on the black which connects to the black of the fan. The white not spliced is your nuetral and connects to the white of the fan. You will have this same setup at the new light. To get power to the light box tie the black into the blk/wh splice and the white into the nuetral.
billhart
18 years ago
The white/black splice is standard for a switch leg beyond the light/fan. However, it makes it much clearer if you take a permanent marker or black tape and mark both ends of the white that will be hot.
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samneric
18 years ago
Asked: 2. The wiring to the original light fixture is older and does not have a ground wire. The new wiring to make the new light fixture and new switch does have a grund wire. Does this matter?

Answered: 2. Doesnt matter. Just be aware that you wont have a ground even if you connect the ground wire at the switch.

Of COURSE it matters! The NEC doesn't permit extending a non-grounded circuit without having run a grounding conductor back to the service grounding electrode system - either at the service or at a grounded subpanel supplying the ungrounded circuit. See 250.30(C).

And even if someone were to ignore that requirement, connecting an ungrounded ground wire to ANY equipment will only ensure that a ground fault at one end of the wire would be shared by equipment connected to the other end. The light housing becomes hot, then so does the switch. Awareness is a poor insulator.
asak9
18 years ago
I stand corrected. Thanks for picking that up.
pjb999
18 years ago
Hmm ya think? ;-)

If the jbox is metal and the wiring is the armoured stuff, it may be the armour itself is the ground, but hopefully someone who knows more will confirm this...otherwise you may have to rewire at least that section.

What I use to re-colour white wire when denoting it black as a switchleg is some paint-on electrical insulation I got from from a nautical store, I doubt it's rated for mains electricity but it's fine to paint over the white insulation...
aft1
Original Author
18 years ago
"The NEC doesn't permit extending a non-grounded circuit without having run a grounding conductor back to the service grounding electrode system - either at the service or at a grounded subpanel supplying the ungrounded circuit. See 250.30(C). "

Thanks, but can anyone translate this? Does it mean a ground should be run back to the fuse box? Or just the previous starting point/junction? And is it possible that the line is grounded another way, like to some old metal piping in the attic?

Thanks!
billhart
18 years ago
It means there needs to be a continuous metallic path back to the fuse/breaker box.

Using unrelated piping such as the heating or plumbing system for the ground path (aside from the required bond where water pipe enters the house) is frowned on because someone working on the pipes might open the path and get a shock from any leakage the grounding conductors were carrying. Also, there might be insulated joints somewhere in the piping that would prevent it from serving as a ground path.

I doubt your wiring is in armored cable as someone mentioned, but if so, that can be part of the grounding path. I would not rely on old "BX" that does not have a bare wire inside, however, as the spiral metal alone has too much electrical resistance. A ground fault (inadvertent connection from hot to the BX casing) could make it overheat and start a fire without blowing the fuse.
aft1
Original Author
18 years ago
I've found a newer, grounded line to use for the new light... But I am curious about this insulated joint issue? I believe ground-less line is grounded to old, unused gas lines in the attic crawl space. (These are gas lines that brought lighting, kind of like kerosene lamps?) But I just had the attic filled with cellulose insulation and I am wondering if the pipe grounds are affected by this?

Thanks!