Another wiring question

[SteveB]

[?]
rewiring my garage (shop)put in a new panel and placing outlets. Since this is a block wall garage would it be wise to use shielded wire (conduit or BX cable) (using 12/3 with gnd.)

thx

S

[WoodRook]

Follow your local codes. I ran PVC conduit for the peace of mind since I had to surface mount my outlets on my concrete walls. If you run conduit, don't use romex cable, use "single strand" conductors instead (much easier to pull & no heat considerations).

[John Hunter]

Depends on what your local code requires. I personally like to run thinwall since I can go back and pull in more wires if my needs expand.

[don_hart]

Most localities will require the running of conduit. Some of them will require that it be EMT and not PVC but this is dependant on local authorities. Whenever using conduit you must use indvidual condutor wires and not romex.

[mschrank]

Don,

Is that no romex in conduit a code type of recommendation, or just because it's easer to pull individual wires through? I've often seen romex inside conduit...and was planning on doing it that way for an upcoming project.

Mike

[rbfunk]

Mike,
Rather then have you wait for Don, I'll jump in here.
If I remember correctly, The issue with Romex(r) is the amount of area it takes up in the conduit. The Federal code limits the amount of space that wires can take up in the conduit and Romex is considered a circular conductor with a diameter equal to the maximum width of the cable. Your state or local code may just forbid Romex in conduit.
And I have no idea what Steve has to do up there in Canada. Their codes are a lot stricter on some things from what I have heard.
Bob

[WoodRook]

I think the bigger problem with romex inside the conduit is heat build-up. You essentially have double insulation since the romex itself is insulated & the conduit provides another layer. At least that's what I was told.

And pulling romex through the conduit would be a bear (unless you had a large diameter conduit).

[don_hart]

WoodRook is right the problem is with heat. And yes it is a code requirement.

[mschrank]

You guys are great. It's good to learn this stuff now rather than when the inspection happens. I've only recently started boning up on electrical, and so far I've found several no-no's in my existing runs. Kinda makes me nervous about the stuff I can't see.

Mike

[mschrank]

Just thought of something else...
Currently, my breaker box contains nothing smaller than 20-amp breakers, and all the wiring I've seen is 12/2. So why are all of my existing devices (outlets) 15-amp? I was planning on replacing all the outlets in my garage (can't wait to start calling it a "shop") with 20-amp outlets, since the wiring and breakers are rated for that. Am I missing something?
Mike

[ejs1097]

quote:Originally posted by mschrank

Just thought of something else...
Currently, my breaker box contains nothing smaller than 20-amp breakers, and all the wiring I've seen is 12/2. So why are all of my existing devices (outlets) 15-amp? I was planning on replacing all the outlets in my garage (can't wait to start calling it a "shop") with 20-amp outlets, since the wiring and breakers are rated for that. Am I missing something?
Mike

Correct me if I'm wrong but that doesn't sound good. It's my understanding that the breaker must be the weakest point. If you have a 15amp outlet on a 20amp breaker the outlet can fail before the breaker trips leaving for a dangerous situation.

[Tom Miller]

quote:Originally posted by ejs1097

Correct me if I'm wrong but that doesn't sound good. It's my understanding that the breaker must be the weakest point. If you have a 15amp outlet on a 20amp breaker the outlet can fail before the breaker trips leaving for a dangerous situation.

The theory is that something that truly requires 20A will have a plug that won't fit into a 15A receptacle.

I don't think there's anything wrong with having a 15A receptacle on a circuit that can otherwise support 20A, and I think this is done all the time.

Regards,
Tom

[WoodRook]

Tom is correct. Something that truly requires a 20A circuit has a plug configuration that is different from the typical polarized/grounded plug. One of the vertical legs has a short "arm" perpendicular to the vertical leg (poor description but I hope it suffices).

[BobSch]

quote:Originally posted by WoodRook

Tom is correct. Something that truly requires a 20A circuit has a plug configuration that is different from the typical polarized/grounded plug. One of the vertical legs has a short "arm" perpendicular to the vertical leg (poor description but I hope it suffices).

If you look at the drawing you'll see the 20 amp socket will accept a 15 amp plug, but you can't put a 20 amp plug in a 15 amp socket.

[mschrank]

So, is there any harm in putting in 20 amp outlets (provided the wiring and breakers are rated for it)? If I don't have any tools that require 20 amp, is there any benefit to installing them?

I remember reading some code guidelines somewhere...I think it was for somewhere in Canada...that mandated no greater than 15 amp circuits in certain rooms. That leads me to believe there may be some potential hazard associated with 20 amp circuits.

Mike