wire choices

[jives]

Hi all:
I'm almost embarrassed by asking this, but I need idiot-proof wiring advice. I've built and fixed many things, but household wiring has never been a strong suit. Anyway, I'm getting ready to insulate and panel the inside of my garage but need to pull the wires first. Problem is, I'm not sure what wire to get. I've read much, but the types of wire (e.g,. 12/2/2, Romex, NM-B, THHN, etc) are rarely specifically identified in the instructions I've been reading. What I'm really looking for is a specific name & label, or link to the exact cable I need. Here are the specs:

--Garage with 100 A subpanel from the house (not yet installed).
--Standard 110/120 V outlets (perhaps 12 total on 2 or 3 different circuits, not included garage door openers on their own circuit) placed around the perimeter, wires in the walls. I'm guessing this could be Romex 12/2 NM-B with ground, like this for use with 20A circuits:
http://www.lowes.com/pd_70111-295-28828269_0__?productId=1193433

-- 120V ceiling lights, controlled by 3 way switches. I'm guessing Romex 12/3 with ground, like this for use with 20A circuits:
http://www.homedepot.com/p/Romex-250-ft-12-3-Solid-SIMpull-NM-B-W-G-Wire-63947655/202316276

--At least two 240V outlets to run 240V electric heaters and perhaps a welder in the future. Perhaps something like this with a 40A circuit:
http://www.homedepot.com/p/Southwire-125-ft-8-2-Black-Solid-NM-B-Wire-28893602/202316591

I welcome advice.

 

[ddawg16]

NM and Romex are the same thing. NM = Non Metalic

You basically have the right stuff selected.

On the lights, unless you are running incandescent, I'd go 14/3. Much easier to work with....especially over head.

Per NEC....

20A ckts....12/2
15A ckts....14/2 (14/3)

Higher amps....sized per NEC table.

 

[simpler=better]

Two side notes:
If it's a constantly-on circuit (heater, lights, etc) then you want to oversize a little.
For example:
15amp heater-put it on a 20amp circuit and 12gauge wire

Bigger is better-use oversized junction boxes for your sanity.
For example: single outlet, put it in a 2gang with a "mudring" that bring it down to 1 outlet. Now you have plenty of space to work.

Use two or more lighting circuits, so if something pops you can still see.
Ex: front half of shop on breaker#1, rear of shop on breaker #2

 

[theoldwizard1]

-- 120V ceiling lights, controlled by 3 way switches. I'm guessing Romex 12/3 with ground, like this for use with 20A circuits:
http://www.homedepot.com/p/Romex-250-ft-12-3-Solid-SIMpull-NM-B-W-G-Wire-63947655/202316276

Lighting is almost always on a 15A circuit and 14 guage wire, unless you are running a bunch of ceiling fans in addition to the lights.

Depending on what year NEC your area is using, many location now require a hot and a neutral in both the switch box and the ceiling box. Therefore 14/3 is necessary, or, if it is a 3 way switch, 14/4. Future proofing.

 

[theoldwizard1]

NM and Romex are the same thing. NM = Non Metalic

Romex is a brand name owned by Southwire.

Like Kleenex and facial tissue.

 

[theoldwizard1]

Two side notes:
If it's a constantly-on circuit (heater, lights, etc) then you want to oversize a little.
For example:
15amp heater-put it on a 20amp circuit and 12gauge wire

Not sure why you recommend this. The breaker will protect the wire.

 

[shawhite]

Price difference between 14-2 and 12-2 are negligible I would just run all 12-2.

 

[nadogail]

IMHO, if you are going to need only a small amount of 14 gauge NM, just use the 12 gauge.

This will eliminate having two leftover coils of wire.

 

[Cmreschke]

.

Depending on what year NEC your area is using, many location now require a hot and a neutral in both the switch box and the ceiling box. Therefore 14/3 is necessary, or, if it is a 3 way switch, 14/4. Future proofing.

What? 3 ways do not require a constant hot in both ends. There is nothing that the op wants to do that will ever require the use of 4 conductor with a ground cable.

All of your switching can be done correctly to code with 12/2 (unless doing 3 way switching) for travelers you need 12/3. You do not need 12 2 2 or anything like that.

 

[Mr. T]

Not sure why you recommend this. The breaker will protect the wire.

I believe he was referring to the need to increase the conductor and OCPD size for continuous loads to at least 125%.

 

[Charles (in GA)]

Two side notes:
If it's a constantly-on circuit (heater, lights, etc) then you want to oversize a little.
For example:
15amp heater-put it on a 20amp circuit and 12gauge wire

Not sure why you recommend this. The breaker will protect the wire.

Because 80% of 15 amps is 12 amps max, and 80% of 20 amps is 16 amps max. Specifically heaters (always), and lighting if expected to be on for more than 3 hours continuous, is considered a continuous load and the 80% rule comes into play.

I believe he was referring to the need to increase the conductor and OCPD size for continuous loads to at least 125%.

You are actually not oversizing anything, you are simply restricting the load on the circuit to 80% of the circuits capacity, and size accordingly. I guess you can look at it the other way and take the expected load, and figure 125% of that for circuit sizing. Either way, its the 80/125 rule that is the issue.

Charles

 

[jives]

Thanks, all. Your conversation got a bit over my head, but for now I think I can get away with 12/2 to wire the outlets and 8/2 for the 240V, 40A circuits. I'm only doing the bottom 8' of the garage this summer, so I need to get those outlets and switches in. I'll leave the sub-panel area unfinished. Garage is 14' high at eaves, scissor trusses with 20' interior height at the peak. The 14/3 (or 12/3) for the ceiling lights and 3-way switches can be installed later, after I figure out my lighting and ceiling choices.

Gracias.

 

[Dagny]

20 amp switches cost a lot more than 15 so even if you use 12-2 put it on a 15 for the lighting

 

[theoldwizard1]

What? 3 ways do not require a constant hot in both ends. There is nothing that the op wants to do that will ever require the use of 4 conductor with a ground cable.

IANAE, but the "latest" NEC requires a hot and a neutral to be in ALL junction boxes. Your area might not be using the code level.

 

[theoldwizard1]

Because 80% of 15 amps is 12 amps max, and 80% of 20 amps is 16 amps max. Specifically heaters (always), and lighting if expected to be on for more than 3 hours continuous, is considered a continuous load and the 80% rule comes into play.

Never heard this one. Obviously only applies to "hard wired" items.

 

[Falcon67]

Price difference between 14-2 and 12-2 are negligible I would just run all 12-2.

That's what I did.