Branch Wire: Solid vs Stranded

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captain kirk key

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Hey everyone, I need some help convincing an electrical engineer to allow us to install stranded #12 AWG & #10 AWG branch wire. For some context the project is a large warehouse that will be converted into an upscale office. Basic commodities will be used throughout: EMT, MC cable, etc. The project has boiler plate specs calling for solid #12 AWG & #10 AWG. The electrical engineer responded to an RFI and said "please use #12 AWG solid copper, as the norm in commercial project wiring installations." Solid branch #12 & #10 is not "the norm" (at least here in California), and we certainly don't want to be pulling solid wire throughout the building. Does anyone have any suggestions on how to persuade the engineer to allow for stranded branch wire? He's a very nice guy and in previous meetings has admitted has no field experience and "trusts our expert opinion on application." Thanks!
 
It might be hard to convince someone who's asking for something that is basically dumb because there is no real evidence that solid is better. Except for MC cable we uses stranded everyday, all day and have been doing so for decades. I've seen more damage done to solid conductors being pulled than stranded. IMO #10 solid should be banned from being pulled into raceways.
 
infinity said:
It might be hard to convince someone who's asking for something that is basically dumb because there is no real evidence that solid is better. Except for MC cable we uses stranded everyday, all day and have been doing so for decades. I've seen more damage done to solid conductors being pulled than stranded. IMO #10 solid should be banned from being pulled into raceways.
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Exactly, because he's never pulled wire himself, he doesn't understand how awful solid can be. Well, I'll keep brainstorming ideas of what to include in this follow up RFI.
 
I've been on a number of jobs in the past mostly military projects that had it in the job " specs" to only use solid wire. If it's not in the specs I wouldn't. I would try to explain that it's much harder to pull in conduit. U could even say that because of this the conductors could get damaged while pulling. Also maybe explain how it may take longer because of the difficulty in the wire pulls & that the job wasn't bid that way. Finally tell him that if u ever wanted to add extra circuits in the conduit for future expansion it would almost be impossible without pulling out all the other conductors. Maybe even physically show him the dirferance in flexibility between solid and stranded . Hopefully this helps.

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Jake@01 said:
I've been on a number of jobs in the past mostly military projects that had it in the job " specs" to only use solid wire. If it's not in the specs I wouldn't. I would try to explain that it's much harder to pull in conduit. U could even say that because of this the conductors could get damaged while pulling. Also maybe explain how it may take longer because of the difficulty in the wire pulls & that the job wasn't bid that way. Finally tell him that if u ever wanted to add extra circuits in the conduit for future expansion it would almost be impossible without pulling out all the other conductors. Maybe even physically show him the dirferance in flexibility between solid and stranded . Hopefully this helps.

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I think you hit some great talking points in this response. This is very helpful, thank you.
 
When I first started in the trade I used mostly solid #12. Never solid 10. Solid 12 is easier to push through runs with out using a fish tape where stranded will bunch up. Solid is also easier to form in panels making them look nicer. The past 25 years I use stranded THHN and MC cable 99% of the time.

I don't do really large projects so the engineers will create a set of drawings but never actually never see the project. Unless the engineer is going to be inspecting the project I would have no problem using stranded even if the plans spec solid.
 
curt swartz said:
When I first started in the trade I used mostly solid #12. Never solid 10. Solid 12 is easier to push through runs with out using a fish tape where stranded will bunch up. Solid is also easier to form in panels making them look nicer. The past 25 years I use stranded THHN and MC cable 99% of the time.

I don't do really large projects so the engineers will create a set of drawings but never actually never see the project. Unless the engineer is going to be inspecting the project I would have no problem using stranded even if the plans spec solid.
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As much as I would like to move forward with stranded and not say anything, there's just too much risk. This is a multi-million dollar project with hundreds of thousands of dollars in branch wire alone. If we get called on it, game over.
 
captain kirk key said:
As much as I would like to move forward with stranded and not say anything, there's just too much risk. This is a multi-million dollar project with hundreds of thousands of dollars in branch wire alone. If we get called on it, game over.
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Then I would try and have a discussion with there engineer to see why he feels solid is necessary.

To me the solid vs stranded is installer choice and makes no difference in the end. If you are going to be terminating wires on to screw terminal the solid is a better choice but we usually use devices with pressure plates.
 
If it's that large of a project than I agree with you & it should be at least talked about before moving forward. I don't know if u r a company owner or your a foreman on the project? When I've ran large jobs there is usually a project manager. I bring up the topic & let them battle it out with rfis & email .Maybe at least bring it up to the project manager or whomever bid the job & ask for there imput. At least this way if it becomes a huge issue they're aware of it. On a project of that size pulling solid wire would add a lot of man hours to the job. I would point out some of the suggested benefits of using stranded. Then stand my ground .

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captain kirk key said:
Exactly, because he's never pulled wire himself, he doesn't understand how awful solid can be. Well, I'll keep brainstorming ideas of what to include in this follow up RFI.
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At this point, I would not follow up with an RFI. Pick up the phone and give the engineer a call. Talk him through your concerns and preferred approach. If his rational is that solid #10s and 12s are commonly used in commercial work, maybe explaining that it is not how you see things in the field would help. Maybe a compromise where you pigtail devices with solid conductors, but use stranded for the branch circuit wiring. You aren't violating the NEC, so it is really a design preference. As an engineer, I couldn't care less if the contractor uses solid or stranded conductors. Whatever a contractor is most comfortable using is fine with me.

After you and the engineer come to an agreement, then you can follow up with a confirming RFI to get the decision documented.
 
d0nut said:
At this point, I would not follow up with an RFI. Pick up the phone and give the engineer a call. Talk him through your concerns and preferred approach. If his rational is that solid #10s and 12s are commonly used in commercial work, maybe explaining that it is not how you see things in the field would help. Maybe a compromise where you pigtail devices with solid conductors, but use stranded for the branch circuit wiring. You aren't violating the NEC, so it is really a design preference. As an engineer, I couldn't care less if the contractor uses solid or stranded conductors. Whatever a contractor is most comfortable using is fine with me.

After you and the engineer come to an agreement, then you can follow up with a confirming RFI to get the decision documented.
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This sounds like a great approach to the situation. With quad outlets being much more common on our jobs than single duplex, it's pretty much company standard that we pigtail all devices with solid wire. Thank you for your input!
 
I would just tell him that almost everyone now uses stranded simply because it's better. If it weren't no one would use it.
 
Send him a link to this form and this thread before he makes his final decision. After that it is what it is.
You can also use the approach of stock in hand. Maybe compromise on all home runs and any raceway with more than three conductors.

Like your handle. Cool name
 
captain kirk key said:
As much as I would like to move forward with stranded and not say anything, there's just too much risk. This is a multi-million dollar project with hundreds of thousands of dollars in branch wire alone. If we get called on it, game over.
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You need to work this out before you pull a single piece of wire. Years ago we pulled 4 floors worth of lighting homeruns all #10 stranded and they made us pull out all of it out and replace it with solid. A complete nightmare.
 
electrofelon said:
Man, I'm so glad my work is pretty much all "design- build". I would lose my mind having some engineer requiring things he not only knows nothing about, but has no business being involved with in the first place.
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I couldn't agree more. You wonder where these guys get this stuff. :unsure:
 
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