bathroom vent fan re- wiring

[John H.]

I had a solar tube light system install in my bath, which is nice but now I have the problem that the vent fan fan only turns on with the lights. I climbed up into the attic space and there's 1/2 inch metal wraped romex from the fan to a junction where it meets the light wires, from there a single line goes down the wall . I guess what I want to do is access the wires to the fan and run a separate line down the wall but I cant access them at the junction since there are copper pipes covering them. So that leaves the fan box itself, with the power diabled, I can cut the romex from the fan and wire nut some 12/2 line and feed it down the wall to a new 2 line switch. Does this sound Ok Is there an attachment that clamps on to the 1/2 metal caseing to the 12/2 romex. Should I just get some metal cased line instead? I was thinking the plain line will be easier to pull through into the box than the metal cased line?

TIA

[~^Johnny^~]

Install a relay switch. Phone wire or bell wire is a lot easier to fish through existing openings than 12/2 NM. And solid state relays aren't that expensive, and old 16 volt bell transformers are a dime a dozen. And you can do neat things, such as add time delays, like a

10 minute turn-off delay, etc.

[trader4]

A transformer and relay? Good grief! He has access to the fan and area above in the attic. What's so hard about doing it the straight forward way he proposed? It's no big deal getting another romex down a wall from above to the existing switch location, as opposed to bell wire and a more complicated hack job.

Also, no need for 12/2 romex, 14 gauge is fine, unless you already have

12 gauge. And yes there is a cable clamp for romex that will fit an extra knockout in the fan. Not sure what he means about cutting the existing wire, as it sounds like it should just be done from inside the fan box, where he can disconnect and cap the existing wire and install the new run.

[buffalobill]

a guess: did this work properly before the wall switch was recently replaced? if so rewire the switch on the wall correctly or replace it with the proper switches first after you have your electrician check the circuit and switch and ceiling device with his multimeter. do we presume that the solar tube is not electrical?

John H. wrote:

[~^Johnny^~]

What hack job? Relay switches are becoming more and more prevalent. If you think about it, all motion sensor lamps are controlled internally by relay switches. X-10 type systems use wireless relay switches.

Second, why tear up drywall or run unsightly surface raceways, if you can fish low voltage wires through existing holes?

I've seen entire buildings hard wired with relay switches. New construction. It may sound ridiculous, but it makes sense, if you think about it.

[trader4]

Yes and both of those systems are far more complex, expensive and failure prone than a simple wall switch, which is all that's needed in a bathroom.

Who said anything about tearing up drywall or running unsightly raceways? The OP said he went up in the attic and can access the bath fan area from there. Now, how hard is it to drill a hole in the top plate, drop a single cable down and put in a new wall switch? It's simple, straightforward and the preferred method that's used by everyone from electricians to homeowners every day.

Makes no sense for this simple bath fan switch. The OP already was on the right track to a simple solution.

[~^Johnny^~]

Not hard, provided there's no insulation, fireblocking, etc. Don't know; I'm not there; I can't see it. A fishing line won't snag on insulation if it's taped up well.

[~^Johnny^~]

Technically, it's a code violation to splice outside a junction box. But it's not really that unsafe, considering all the K&T wiring in existence with soldered and taped connections.

Fishing NM or armored cable down the wall may be a problem - then again, maybe not.

Modern codes have required insulation in all walls, so how old is your construction?

Also, you could J in the fan housing, if there's an extra 1/2 inch knockout. That would eliminate cutting the cable.

Romex (NM cable) is fine, but then again, it may be a local code violation. The trouble with code violations is not avoiding the building inspector (it's a bootleg install anyway), but avoiding any possible insurance snags, should something go wrong later and necessitate a claim. Insurance adjusters are assholes, and will look for ANYTHING to cut payments.

I wasn't kidding about the relay switch. It's probably how I would do it, just for the flexibility (no pun intended). But to run a regular switch leg, I'd try to J inside the fan box, local codes permitting.

BTW: copper pipes obstructing access to an electrical J box is a Bozo No-No. Bad, BAD plumber!!! :-)

[trader4]

You should stop giving advice, because telling someone it's just a technical thing and no safety issue to do wiring splices outside of boxes, proves beyond any doubt you are a hack.

Now maybe I missed something, but when did code get changed to require insulation in all interior walls, like the bathroom wall in question?

[Jeff Wisnia]

In which case you'd prolly find you couldn't run the fan unless the lights were ON.

Because, it sounds from what the OP says that the guy who recently installed the solar tube light system just grabbed power for them off the existing switched feed to the fan and told the OP to use what used to be the fan switch to control 'em both. I could be wrong about that, but it's probably the "way to bet".

I've equipped the fans in all our bathrooms with "wind up" 0-60 minute timers so we can leave the fans running for a while after using the john, without having to remember to go back and shut them off.

Timers like these:

Jeff

[John H.]

thanks for all the info, I'll take everything into consideration. I'm thinking I'll just go with my original plans. . I'm not an electrician but this job seems so straight forward that I can handle it.

I think a timer is a good idea if you got a houseful of kids who will forget to turn off the fan, I'm single and my family rarely comes over. Separating the two lines and running a new fan line down the wall seems the most straight forward way for me to go. I'll get my neighbor to help me get the line through the box.

Does anyone know a good text for the weekend DIY for electrical jobs? There are some more upgrades I want to do, I'm doing the easiest first. Thanks john

[~^Johnny^~]

So it is. The line isn't hot, it's swithed from the light switch.

A hot lead has to be grabbed from somewhere, if the fan is to run completely independant of the light (whether the light is on or off).

And the switch leg probably J's inside the box that is obscured by the plumbung. ;`(

"Dewerks" is "Screwed" spelled backwards.

[~^Johnny^~]

Where I live, 16 - 17 years ago, at least.

[~^Johnny^~]

You'll probably have to heat it from the hot wire to the light switch, if you can gain enough slack in the line to install a junction box. Usually you can't, and in this case, what I would do, is install two junction boxes near each other, adding cable between them.

An alternative is replace the single switch box with a duplex box, and you already have a hot lead there. Then use half a new Romex or whatever, to run from the new switch back up to the fan. You can use the other wire to send a hot back up to the fan box, for later use, e.g., a new unit later on down the line that might need it.

If the wiring is in BX (flex conduit), then you may be able to fish an extra wire up through it. This may be easier than grabbing a hot in the attic, on the same circuit.

[trader4]

Very informative and useful information, as usual. Would that be NYC or Bosnia?

[John H.]

Ya know, I woke up in the middle of the night and realized that the way I was going to do it wouldnt work, no power. Would need to do it the way you described.