There are no GFCIs in the unfinished part of our basement, so I have decided to replace the receptacle above a work table. This was wired with 12-gauge BX. The BX connects to 12-gauge AC cable (the bonding strip bent back and wrapped around the metal sheath). I haven’t found anything else on the circuit (so far).
Can I use a regular, 15-amp GFCI here?
Also, the cables don’t have ground wires, but the voltage tester lights up when touched to the black wire and the box. Does that mean that I don’t apply the “No equipment ground” sticker?
Janet
Replies
The AC cable jacket is your ground so you are OK there. The older BX was listed as ground back in the day but it is inferior to the AC with the bonding strip. I still would not worry about it behind a GFCI.
The circuit breaker for this receptacle has "20" on the tip of the switch. What does this mean? The various breakers say 15, 20, 30, 40, and 100. The main switch at the top of the panel says 200.
Janet
That means that it's a 20-amp circuit, and it must have wire that is #12 or thicker. However, a quirk in the code allows receptacles (and, I believe, GFCIs) rated 15 amps to be on a 20-amp circuit, and this is quite commonly done.
The NEC allows multiple 15a receptacles on a 20a circuit because the configuration of the plug prevents using any single piece of equipment that draws more than 15a.
The device itself is rated to pass through 20 amps.
Thanks, guys! Saved me a trip to Home Despot.
Janet
What gauge wire is required on the breakers marked 30 or 40?
Janet
What gauge wire is required on the breakers marked 30 or 40?
Janet
Check out an "ampacity
Check out an "ampacity chart", eg http://www.cerrowire.com/ampacity-charts . But note that the current capacity of wire varies depending on the insulation ("NM-B" is conventional "romex", while the THW... varieties are "loose" wires intended to be placed in conduit). For romex, you need #10 for a 30 amp breaker and #8 for a 40 amp breaker.
(Note that you should not place conventional light fixtures or receptacles on a circuit larger than 20 amp.)
Adding conduit
If I add a box downstream from the GFCI, the cable will need conduit because it won't be within a wall cavity.
I found some EMT and offset connectors to the box, but these connectors don't allow use of the romex clamp you showed me. Are clamps not required when the cable is in metal conduit?
Janet
You don't always need conduit to protect cables but it is not a bad idea if you even think it might be subject to "physical damage" (the test).
If you are using a raceway, you do not need a clamp where the cable enters the box, just the proper conduit connector. If it exits the conduit somewhere that is not a box, (sometimes done when the cable is above the area considered subject to physical damage)you either use a bushing or one of those connectors that integrates a cable clamp and a conduit connector on each end.
Although EMT is an excellent wiring method and gives a very professional look, there are other more homeowner friendly options. You can use rigid nonmetallic conduit (gray PVC) virtually anywhere you can use EMT. Most places are also suitable for Electrical Nonmetallic Tubing (blue smurf tube).
I thought of EMT because there was some stashed in the basement, but I'm certainly open to alternative material, mainly because I don't have access to a conduit bender.
The existing wiring is surface-mounted BX. Can I assume that BX does not need conduit?
Janet
BX/AC are usually considered to provide some protection from physical damage but the whole physical damage thing is not well defined so the standard is far from "standard".
The easiest raceway type wiring method is ENT/Smurf Tube. It is flexible enough to run almost anywhere and you do not need any special tools at all. Everything snaps together and you can cut the tube with a sharp knife.
Next would probably be Rigid Non metalic Conduit (the gray stuff). You should get a PVC cutter and it glues together with PVC cement.
EMT requires a hacksaw or some other metal cutting tool, a bender and something to ream the burrs out of the cut ends.
BX in conduit
I've seen angled EMT connectors that eliminate the need for a conduit bender, but it must be for romex—I don't think BX can make that sharp of a bend. So, if I were to put the BX into conduit, it would have to be the flexible type?
Janet
There is no good reason to put BX/AC in conduit.
Speaking of raceways
One of my library books cautioned against "overloading" by using outlet multipliers like this: 35626.jpg. Their recommended alternative was to surface-mount an additional receptacle and connect the two using a raceway. The accompanying picture showed a set-up that was pretty unsightly but supposedly safer.
Why is this safer? It seems to be the same amount of power used on a single circuit.
Janet
I agree, if they are on the same circuit, adding another receptacle is not really doing anything but placating a NEC rule without actually adding any safety.. If you were talking about adding one that eliminated an extension cord you might have a case.
BTW the "legal" way to do this is with a surge suppressor strip with an over current device in it.
That is common if you are talking about a computer or entertainment center where you have a lot of low power pieces of equipment..
I wouldn't get your shorts in a knot about using a few "cube taps". You shouldn't use them for high-amp equipment, and you shouldn't use them by the dozens, but a few, for "small" loads, are fine.
And my favorite way to permanently add more outlets is to replace the single box with a double box and two duplex outlets. I've done this on a couple of occasions, and the "surgery" to do it is not that difficult.