Hey Guys,
Need some help with wire. Print on the wire jacket says: cerro wire vinylon-A 4 AWG (UL) THHN or THWN-2 or MTW or AWM GR2 Sun. Res. VW-1 600v -c (UL) TWN75 or T90 Nylon
I don’t understand everything it’s for. When it says or between some items does that mean it can be used for any of the listed things or am I totally wrong? Is this good for wet locations? I am planning to use it for service wire to a subpanel in a detached garage. It will be run through 1.5 inch grey pvc conduit for 180 feet. What is the highest amp breaker I can use figuring in the voltage drop. I plan on running three of these wires and 11 #12 wires all in the same conduit. Is this amount of wires okay? (#12 wires will be for some three way switches and a garage door opener) Also, what gauge wire would you use for a garage door opener at this length? I know it’s alot, any help will be much aopreciated.
Replies
It's #4 wire and UL listed to meet the specs for THHN or THWN-2 or MTW or AWM.
THHN is your general-purpose wire -- "When used as type THHN, the conductor is suitable for use in wet or dry locations at temperatures not to exceed 90°C or not to exceed 75°C in oil or coolants".
THWN-2 is another designation for essentially the same thing as THHN. You generally see the same wire rated both ways. (The old THWN without the "-2" had a lower temperature rating.)
MTW is machine tool wire -- "When used as type MTW, the conductor is suitable for use in dry locations at 90°C, or not to exceed 60°C in wet locations or where exposed to oils or coolants".
"Unlike most wire categories, appliance wiring material (AWM) is a Recognized Component used in UL Listed or Classified end products. AWM wires are intended as factory-installed or factory-provided components of complete equipment submitted for investigation, rather than for direct separate installation in the field. The final acceptance of the component depends on its installation and use in or with complete equipment submitted to UL."
Don't ask me why there are so many different categories that mean essentially the same thing.
#4 THHN has a basic ampacity of 95 amps. But, according to the rules this means it must be protected by a 70A or smaller breaker and should not be subjected to a continuous load of greater than 56 amps. At 56A load there would be a voltage drop of about 6V in 180 feet, which is a bit much. It would probably be best to limit the load to about 40A, or use a larger wire.
Running these wires and that many #12s in the same conduit could represent a problem for both. Some derating is likely required by code.
A little curious as to why the GDO would be run off a separate set of wires and not off your new panel. In any event, a small (1/2 HP) GDO should be fine on 180 feet of #12, though it would be better to have it off the panel.
You are better all around to put the feeder (#4s) in a separate conduit. You would have to derate them (use lower amps) if you don't.
We would know more about derating the "11" #12s if we knew what they were doing but a general rule is you don't really have any impact from derating "small conductors" (12 and 14) until you get over 9 carrying current. That is because of the artificially loww rating in 240.4(D) that you don't have to use when derating. #12 can only have a 20a breaker but you can start derating from the 90c column which is 30a.
Before derating your #4s are good for 85a (using the 75c column) and the W in THWN means wet location. The -2 means you can use the 90c column to derate. As long as you only have 3 it is not an issue
Why would you need to switch a light and open a garage door from 180 ' away? There are probably more ways to skin the cat you are thinking about her... What are you trying to accomplish with this wiring?
(Dammit -- lost my post again!)
The GDO control signal is low voltage and MUST NOT occupy the same raceway as power wiring. It doesn't need a raceway at all, but of course you have a problem getting it under the driveway. Might I suggest using a keypad instead?
For the light switch lines you may want to consider using X-10 remote controls rather than separate wires.
Derating is confusing to most people. Basically, if you have two wires that individually could handle X amps, the two in a common raceway are limited to something less than 2X amps, since they each interfere with the other in terms of dissipating enough heat to avoid overheating. The rules for dealing with this are, unfortunately, pretty arcane.
(I don't think you're going to get 3 #4s and 11 #12s, plus some ground wires, through a 1.5" conduit 180 feet long.)
It won't be easy to pull anything 180 feet but 11 #12s, 3 #4s and an 8ga ground is only 0.4195 sq/in and would legally fit in a 1 1/4 pipe. If you kept the bends down to two with condolets on each end, it might not be that hard. Get a bottle of Yellow 77 lube and don't be stingy with it.
Oh, yeah, that reminds me -- the garage will need a "grounding electrode system".
X10 is the way to go here. Using the automation stuff will give you greater flexability, safety, and allow you to have more amperage in the garage subpanel. Looks like the low voltage controller is about $18, I didn't see what the other stuff cost.
http://www.x10.com/news/articles/0302_garage.htm
The problem with running the door opener in the same conduit: If the little wires get energized with the big voltage... the stuff the little wires connect to ALSO get the big voltage that they weren't built for. These types of situations commonly also involve smoke, sparks, and eventually open flame.
Garage door controls are going to be 24VAC and you are going to have problems legally putting that in your conduit with the feeders. You can get around that problem with a 120v coil relay that switched the garage door circuit.
With some careful planning you could use the hot from the light switch and only need one wire for the relay coil.
I am still confused about how you get to 11 wires in the pipe.
2 for the garage door opener and 3 for the light switch. What are we missing?
As for the derating with 10-20 wires in the pipe you are at 50%
You can use your #12s at 15a and your #4s at 50a (rounding up)
If you can get down to 9 that is 70%. The 12s are OK at 20a and you can round the 4s up to 70a.
The ground is free. (for now)
How many 3way switch loops are we talking about? Eight wires would be 3 with one left over.
If you want to follow current code (2005 and up) you really need a ground wire in that pipe. #8 will do it.
X-10 will work if you want to save some wire and squeeze 90a out of your sub panel (with the rounding) but if you actually started using that much you could bump into voltage drop problems.
I would draw up a list of exactly what tasks you want to accomplish from which location. For example: I want to be able to turn off the garage lights from inside the garage, and from inside my house 180' away. Once you have that list made up, give those x10 sales folks a call and they will tell you what gear you need. Might want to google other home automation companies too to see what they offer - x10 was just the first name to come up here as the example.
For lighting power useage... If you had four 500w halogen lamps running in your garage, plus another 4 100w incandesent bulbs burning, do you know how many amps that would draw?
500x4=2000
+100x4=400
2400watts/120v = 20amps.
20 amps is not very much - and that is assuming the most power hungry inefficient lights in use. Most people put a bunch of fluerecent or a mix of halogen and fluerecent. You would be surprised at how little power it takes to brightly light a garage.
Just an FYI, I ran my whole house for a month on 40 amps of power. That's with electric stove and microwave, but no AC. Never tripped the breaker.
On a side note - I'm actually a little worried about your plans at the moment. You have an idea of what you want to get done, but have come up with some faulty methods to do it. If you implement a faulty method in electrical, you can end up with someone getting killed - you, your family or friend, or the next person who buys your house. I'm all for doing things yourself, but please have someone local take a look at your plan and exactly what you are intending to use to implement your plan - they might catch something that you didn't think to ask about here. Like that ground wire for instance!
When I redid my electrical service, the electrical supply store helped me spec out EXACTLY what I needed, and the building inspector caught an issue with my ground wire that I didn't even think about. All this was besides the good advice I initially found here!