Old wiring

Old 02-18-04, 04:28 AM
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Old wiring

I am remodeling a bathroom and purchased a new exhaust fan. I Thought I could handle this simple replacement, but now have questions. First, my house wires have no ground. Do I simply not use the ground provided with the fan? (One end is grounded to the metal housing, the other end would be for me to use) Or should I run a new wire and ground it somehow? Also, the instructions tell you to use wire of the appropriate rating? My house wiring is 14, but I have a book that recommends a bathroom exhaust fan use 12 AWG. What is appropriate? I originally planned on using the old 14 already present for the old fan, assuming it is not wise to connect 12 AWG to the old 14 and making my job a little easier. However, now that I have removed the old walls I see that is exactly what a previous electrician did. At some point in time they hooked up 2 12 AWG wires to the old 14, one was for a light fixture above the medicine cabinet and one to a GFCI. Their actual connections are hidden by a bunch of electrical tape (don't worry, there are wire nuts under the electrical tape). I am wondering if is it safe to use the 12 connected to the 14 and how the GFCI is really grounded since the wires end in this little glob of wire nuts and tape? The GFCI was working before I removed it, but if it is unsafe it would only make sense to fix it now while the walls are torn out. Thanks for your help.
Old 02-18-04, 04:58 AM
Join Date: Sep 2003
Location: Central New York State
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So many questions.

It is safe to use 12 gauge wire on a 15 amp circuit. I do not recommend this, as it serves no purpose and because 12 gauge wire is harder to work with, but it is not unsafe.

In your case someone most likely used 12 gauge wire because it was all they had and they were too cheap or too lazy to go and buy 14 gauge wire.

Your book probably recommends 20 gauge wire for a bathroom fan because there is the possibility that somebody may someday want to install a unit that also features a heater.

If you are replacing a light fixture and your current wiring does not have a ground then you simply do not hook up the ground. This is not unsafe unless the fixture specifically requires a ground.

A GFCI does not need a ground to work properly. It will provide protection without the ground. However, with no ground the outlet should be marked "No Equipment Ground".

Electrical connections should not be hidden by electrical tape. I hope these connections were in an electrical junction box and that they were accessible before the walls came down.

Now, more importantly, you say that you have removed the walls. If you have removed the walls and the ceiling then you should bring the bathroom up to code. I would run a brand new 20 amp circuit to the bathroom from your electrical panel and place the entire bathroom on this new circuit.

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