Wire Length Estimating

[Spudland_Dave]

Next up on my agenda will be to add more recept's in the garage.. Will run 12-2, on a 20A breaker...question is, how much wire do you think it takes to do the "average" 30x50 Garage... I'm just asking because Its clearly cheaper to buy the longest wire available...1000ft Spool vs 250'
I hate to buy 1000' and have 550' leftover, but at the same time....Hitting Lowes or my Electric Supply house every other day for a 250' spool isnt smart either...
How do the Pro's quote or figure something like this out?

 

[moserjj]

At our local box store, wire is the same price in 250' spools as it is for 1000' spools if you compare per ft cost. But for that large garage, i'd get a 1000' spool. it tends to come off that spool straighter too even with the wire feeder wheel thing for the smaller spools (mine always gets hung up or tips over, pita)

 

[lakee911]

Well, it all depends on how you run the wire and how many receptacles. Think about how you'll do it, estimate the distances and add 10% for slop. Sometimes it helps to make sketches or plans for what you want to do.

When I did my unfinished garage I run each receptacle switch up to the ceiling and then accross on runners to best protect them as where I am its a code violation to run them accross unfinished stud walls without protection. Runners on the wall looks silly. This method made for a very neat and clean install but it took a lot more wire.

You might want to think about more than one 20A breaker too. At least put in two or three no matter what your use. At a minimum, put lighting, and the opener each on seperate circuits.

 

[madosta]

Next up on my agenda will be to add more recept's in the garage.. Will run 12-2, on a 20A breaker...question is, how much wire do you think it takes to do the "average" 30x50 Garage... I'm just asking because Its clearly cheaper to buy the longest wire available...1000ft Spool vs 250'
I hate to buy 1000' and have 550' leftover, but at the same time....Hitting Lowes or my Electric Supply house every other day for a 250' spool isnt smart either...
How do the Pro's quote or figure something like this out?

Why in the world would you need 1000' for one breaker? Figure out where you want your receptacles, and the number of them as well as the number of circuits since I'm assuming you wont just have one breaker powering 50 recepts.

As others have said, do a little planning and give yourself some room for "slop".

Have fun!

 

[Gary S]

Well, it all depends on how you run the wire and how many receptacles. Think about how you'll do it, estimate the distances and add 10% for slop.

This is correct. There is no single way to wire a shop, so there is no single number of how much wire you will need to get the job done.
When I did my 24x48 garage, I used about 1000' of wire. You could easily get by on a lot less, or you could put in a lot more wire depending on what you choose to put in.

 

[snorky18]

At our local box store, wire is the same price in 250' spools as it is for 1000' spools if you compare per ft cost. But for that large garage, i'd get a 1000' spool. it tends to come off that spool straighter too even with the wire feeder wheel thing for the smaller spools (mine always gets hung up or tips over, pita)

Same here, exact same price per foot for 250' vs 1000'. 27 cents / foot before tax IIRC.

If you do 1000, I believe it comes on a drum. If you buy the 250, you better buy or build an effective dispenser. I just went through that search, and came up with nothing current production that was priced reasonably and would work for what I wanted. Carlon used to make a good one for <$50 but it is no longer available.

How to estimate: I don't have any rules of thumb. I draw up a detailed plan of where I'm going to put electrical devices, plan the path for the wires, then look at the building to make sure my paths will work. After that I measure all the paths, add up my wire needs, and add slop as recommeneded. For a bigger job I might measure on paper, but for my ~600SF of garage, it's easier to go out there with a tape measure and a notepad.

Honestly though, I usuallly just buy 250' rolls as needed. I'll eventually use it, and it's not getting any cheaper.

 

[Spudland_Dave]

You might want to think about more than one 20A breaker too. At least put in two or three no matter what your use. At a minimum, put lighting, and the opener each on seperate circuits.

Oh there will be much more then a single breaker...probably closer to 5-20A of them just for recepts in the shop end...2 more in the Garage end...

Thanks to all, I guess more then anything, I knew without a doubt 250' wouldnt be enough..when looking at the 1k' spool I was thinking, MAN thats alot of wire...but at the same time, doing my 14-2 for exterior lighting, I'm watching the spool shink faster then I thought.

What do you guys use for Spool Racks? I really got to get setup with something.

 

[Spudland_Dave]

Same here, exact same price per foot for 250' vs 1000'. 27 cents / foot before tax IIRC.

Hmm...could very well be the same here, I just ASSumed it was cheaper longer...

If you do 1000, I believe it comes on a drum. If you buy the 250, you better buy or build an effective dispenser. I just went through that search, and came up with nothing current production that was priced reasonably and would work for what I wanted. Carlon used to make a good one for <$50 but it is no longer available.

We must have been posting at the same time...JUST asked that question...but your right, the 1k comes on a drum. Anything less then 1k comes plastic wrapped. Couple weeks ago I saw and bought a 250' Spool holder from Lowes by Southwire...well worth the 10 bucks. http://www.lowes.com/pd_236833-295-55380701_0__?productId=3380862&Ntt=southwire+romex

Honestly though, I usuallly just buy 250' rolls as needed. I'll eventually use it, and it's not getting any cheaper.

Very true...I've got a bit of 12-2 left over from when we finished the basement oh, 4 years ago...having a few feet leftover doesnt hurt my feelings.

 

[Steevo]

Man, I wish I had been able to find one or two of those when I wired my shop!

I tried to buy one of these from Craigslist, but missed it:

 

[snorky18]

Thanks to all, I guess more then anything, I knew without a doubt 250' wouldnt be enough..when looking at the 1k' spool I was thinking, MAN thats alot of wire...but at the same time, doing my 14-2 for exterior lighting, I'm watching the spool shink faster then I thought.

Since you bring up 14-2, in case anyone is wondering, after you derate to 80% of the breaker value, meaning 16 amps available on a 20 amp breaker w/ 12-2 and 12 amps available on a 15 amp breaker with 14-2 wire, the difference in cost to carry 1 amp for 1 foot on 12-2 vs 14-2 is.... wait for it....

Nothing. Well, at least not a lot on smaller jobs.

I did the math and compared the $/ft/amp carried on 12-2, 12-3 MWBC, 14-2.
14-2 was 1.46 cents per foot to carry 1 amp
12-2 was 1.67 cents per foot to carry 1 amp
12-3 (MWBC) was 1.46 cents per foot to carry 1 amp

13% price difference to carry the same amperage in 14-2 vs 12-2. So whether to use 12-2 vs 14-2 is more a choice of convenience on smaller jobs, unless there's some code that I'm not aware of that would affect it.

On long runs where you are not going to need the entire capacity of the wire, such as a few exterior lights on their own circuit, or smoke detectors, 14 would certainly make more sense.

Whoever did my house did not use a single piece of 14 anywhere. All 12 and bigger. And no there is not a code requirement to outlaw 14 here.

Couple weeks ago I saw and bought a 250' Spool holder from Lowes by Southwire...well worth the 10 bucks. http://www.lowes.com/pd_236833-295-55380701_0__?productId=3380862&Ntt=southwire+romex

Man do I wish I had found that a couple of months ago! I'm going to order one now just to have. Sadly I can't get it from Lowes.com and it's not in stock within 200 miles of me, but I'm sure I can find it somewhere on the internet.

 

[Spudland_Dave]

On long runs where you are not going to need the entire capacity of the wire, such as a few exterior lights on their own circuit, or smoke detectors, 14 would certainly make more sense.

Hmm. never looked at it that way BUT I did wire up all my exterior lights using 14-2, Interior lights are 14-2, GDO Recep will be 14-2...any normal recep will be 12-2.
I'm a fan of alot of seperate circuits...

 

[lakee911]

Hmm. never looked at it that way BUT I did wire up all my exterior lights using 14-2, Interior lights are 14-2, GDO Recep will be 14-2...any normal recep will be 12-2.
I'm a fan of alot of seperate circuits...

Sounds good. Me too.

 

[madosta]

Pure cost didn't go into my 12-2 vs 14-2 debate in my head. My utilization is not near on my 14-2 - it's just a relief on your hands once in a while. I know I have a little girly hands huh? LOL!

 

[Falcon67]

FWIW - I ran 12-2 for everything except the 5kW heater circuit (which required 10-2). My shop is 24x40 and used just short of 1000'. That was for 5 120v plug circuits, and 3 each 240v circuits.

 

[Milton Shaw]

I did most of my shop with emt. That way I can easily change form a 120 20A circuit to a 240 30A or more on any wall. Fed main run 3/4 emt to center of each wall and then ran down walls with 1/2 emt to outlets and put double GCFI in center of wall with each GCFI protecting the left or right circuit. So far I have not needed to add any additional circuits except for a 240V 50A circuit for welder overhead to reach both ends for the shop and keep the extension cord off the floor.

 

[Aceman]

I'd buy a 1000' reel and then use these:

http://www.rack-a-tiers.com/product/6/Rack-A-Tiers-Wire-Dispenser

Or if have a 4 legged stepladder, slide a pipe across the bottom rungs to support the spool.

 

[ddawg16]

Nothing worse than being 1' short on your wire bundle....especially when your pulling 150' sections of wire....AMHIK......

When I'm not sure....I push a fish tape through....then pull back a string.....and use the fish tape to figure out how much wire I need.....and then add a few extra feet to it....

It's a lot easier to cut off a couple of feet vs adding a couple of feet.

 

[68 Bird]

I used about 500' in my 32 x 48.
As for spools, I have always just tore a small hole in the middle of the plastic on the 250' rolls and just let the platic wrapping keep the coil together and feed out what I need through the hole. Works well if you grab the correct end of the wire.

 

[Spudland_Dave]

I used about 500' in my 32 x 48.
As for spools, I have always just tore a small hole in the middle of the plastic on the 250' rolls and just let the platic wrapping keep the coil together and feed out what I need through the hole. Works well if you grab the correct end of the wire.

I used to do that...works fine for small pulls, but typically what happens in the wire gets very twisted. With a spool, the wire comes out straight & flat. Makes it easier to pull and manage.

 

[68 Bird]

I used to do that...works fine for small pulls, but typically what happens in the wire gets very twisted. With a spool, the wire comes out straight & flat. Makes it easier to pull and manage.

No argument there. I have always just taken my time to twist it out flat before I staple. I figure why add one more tool to the mix that I will use occasionally. I mean it's not like I wire, pull it out, add to and re-wire, every other week. I have enough **** laying around the way it is.

 

[Falcon67]

No argument there. I have always just taken my time to twist it out flat before I staple. I figure why add one more tool to the mix that I will use occasionally. I mean it's not like I wire, pull it out, add to and re-wire, every other week. I have enough **** laying around the way it is.

This. I have the time and temperament to spool out 40/50/60' of NM and work it until it's untwisted before pulling. Worth the effort.

 

[68 Bird]

This. I have the time and temperament to spool out 40/50/60' of NM and work it until it's untwisted before pulling. Worth the effort.

To each his own I suppose. 40/50/60 isn't short to you? I guess when I pull wire I like to take my time so a few extra minutes doesn't matter. It's worth not tripping over another unused tool for eternity.

 

[wyliesdiesels]

I'm curious if any $ could be saved by using 12/3, which could cut the footage of wire on the home run sections. You could run 12/3 to the last j. box on the first circuit and then 12/2 from there to the j. boxes for the next circuit. Or run 12/3 to a quad box and then splice to 12/2 for the individual circuits. The savings obviously depends on the cost difference of 12/3 and double pole breakers!

 

[68 Bird]

I'm curious if any $ could be saved by using 12/3, which could cut the footage of wire on the home run sections. You could run 12/3 to the last j. box on the first circuit and then 12/2 from there to the j. boxes for the next circuit. Or run 12/3 to a quad box and then splice to 12/2 for the individual circuits. The savings obviously depends on the cost difference of 12/3 and double pole breakers!

I always try to keep my wiring as simple as possible. I know the pro electricians have some pretty slick methods for saving on material but I ain't one of them. It may work, do the math.

I always cringe whenever I need 3 wire anything, that stuff seems to get spendy quicker, plus I'm always either 5 feet short or have more leftover laying around than I want.