multiple conductors and te NEC

[Pro-Scapes]

We did an install awhile back where we had to run a double wire. Someone told me today on the mike holt site that its a code violation altho it was reccomended to me by an unnamed manufacture and dist.

I cant seem to find a link to the code and dont have a code book on me. Can anyone elaborate on 310.4 where i might be in violation ? someone said you cant run doubles on something as small as 10ga

[NightScenes]

What do you mean, double wire? I don't understand what you are trying to say Billy.

[Pro-Scapes]

ok run was 200 ft approx. No way to get line voltage out there nor place to hide a trans out there with out MAJOR work (will try and go get a pic next week)

We had 6 lamps 4 x 35 and 2x 20 for a total lamp load of 180. Instead of buying 8ga wire a dist told us to run 2 pieces of 10 this brought us to where we could use a 15v tap available on our transformer instead of an 18v tap. I think I should of just put 2 separate hubs in and thats what I was going to do but was told to do it otherwise.

Did Billy make a boo boo ? I think I misread the Cast site where it says use 2 pieces of 10ga... should everything be joined up like its one hub ? basically I ran the 2 pieces of 10ga in parallel. If I made an error I will go fix it and split it to 2 separate hubs this week.

[NightScenes]

Billy made a BIG boo boo!! Unfortunenately, your distributor is not an electrician and I haven't read the Cast thing to know if it was misread. My NEC book is at the office or I would quote it for you. I'll try to remember to look it up. Let me state that you NEVER join two lengths of wire together to make a single run.

Billy, a single run of #8 wire is cheaper than 2 runs of #10 anyway. It's also easier to bury one wire than two. I always have some #8 on hand just in case.

[Ruben Rocha]

310.4 in the 2002 NEC states that parallel conductors need to be 1/0 AWG or larger.
Exception 2 may allow you to use the 10awg as long as all the conditions are met.

[seolatlanta]

Hey Billy-

This is one of those instances (I am speaking here in terms of myself) where you have to either do 1 of 2 things-either go get a larger transformer with an 18 volt tap or pull 2 home runs out there. It has happened more times than I care to discuss when I have to switch out transformers because I didnt have enough voltage at a long run or when a customer adds fixtures.

Dave

[Pro-Scapes]

glad i learned this... I will be going out 1st thing monday and seperating them. Since I already have 2 runs buried out there I will split the load into 2 hubs. I guess I just misunderstood the recomendations. It did seem kinda wierd to me at first but it worked fine.

I will go split it all in half and be ok on monday I should be able to put another splice in the same valve box just seperate the load in half so half is on 1 strand of 10ga and half is on the other strand. Would that be ok ?

Thanks for helping me learn.

[Pro-Scapes]

310.4 in the 2002 NEC states that parallel conductors need to be 1/0 AWG or larger.
Exception 2 may allow you to use the 10awg as long as all the conditions are met.

What are the conditions of exception 2 ? I just ordered an NEC book and will be sur and study it more.

[NightScenes]

Yes Billy you can have both junctions in the same box. Good luck reading the NEC, people make a lot of money just teaching people how to read it. The electrical exams are all open book and most people fail the test just because they don't know how to find the information in the book.

[Pro-Scapes]

I really do try hard to make my workmanship the very best I can. I dont feel stupid for asking about all this. I am happy that I got the oppurtunity to leanr from things. I really apprreciate everyones help.

It bothered me so much that i may of been in violation (at a lawyers house no less) that I just came back from looking. IndeedI I did run it in violation. I simply cut my splice apart...Verified quickly which leads belonged to which lamps and split it with two 35w and a 20w on each run of 10ga. givinh me a total load just over 113 w per 10ga run including the wire and still allowing me to run the 15v tap. Resoldered and tagged my runs and packed it all back inside the valve box.

Took about 30 min to correct this. Thanks again

[steveparrott]

Billy, my apologies if it was me that gave you this advice.

I was under the impression that running the low voltage cables in parallel was OK as long as the combined ampacity restriction was followed. A reading of 310.4 seems to contradict this. None of the exceptions seem to apply. Unless, someone corrects my reading of the code I'll advise against the practice of running two cables in parallel.

For those who have already installed with this method, I wouldn't be concerned - the physics support the fact that, in such an application, the wires will safely carry the current. But the code is the code, so in the future the practice will not be advised.

[Pro-Scapes]

Im not sure if it was you directly but Casts wording on thier wire selection guide is a bit deciving. Where it says double up on wire. I think it should probably be worded more like.

Add another run or run 8ga wire. I didnt have any 8ga nor was any avalible locally so this is why I ran 2 10ga wires. The original install only called for a couple of 35w lamps but we added 4 lights.

Live and learn. It just shows yu never stop learning! All is fixed now! I wasnt as concerend about the saftey of it as much as I was concered about my workmanship being the best it can be.

[NightScenes]

Good job Billy! Now all is well and people have learned something.