solid vs stranded THHN

[ActionDave]

Certainly a matter of preference and what type of work you do. I seem to do lots of work where pulling solid is very difficult, i.e. two - three full boats of #12 in a 3/4 with 3-4 bends....

I've pulled that in 1/2" all day long with solid or stranded. I'm not busting your chops I just notice a lot of electricians seem to think you need 3/4 and I've never understood it.


And for the record I'm a stranded guy all the way.

 

[StarCat]

Solid copper wire especially does not belong in flex conduit that connects to motor or many other vibrational machine loads, and the problem is that there is some kind of militancy surrounding not having stranded on the jobsite which leads to problems and failures down the road, to include broken conductors and single phase conditions.
I have found it to be superior in about 99% of industrial applications and I would use nothing but THHN stranded or MTW in control panels. When I hear old school electricians say that solid is easier to terminate I have to assume that they have not really worked with stranded in much measure. It is very unforgiving if you mess up an intricate pull and have to take it back out of the conduit after having gotten a lot spooled off. There is a lot of narrow mindedness around this subject of solid vs. stranded wire.

 

[Dennis Alwon]

As a design engineer, I most often see the specifications call for solid for some sizes (typically #10 or smaller) and stranded for larger sizes. I have no technical basis for such a requirement. But the NEC is silent on this issue, and anyone telling you there is a code violation here is simply wrong.

Charlie perhaps because it is not compliant to use solid wire Larger than #10, not to mention hard to find, but I think your question is really why is 10 and smaller spec'ed as stranded in some cases. I don't know why.

have heard people say that stranded carries more current and other stuff that doesn't make sense. Even if stranded is capable of a higher current it is still rated for the same overcurrent protective device as solid.

I had a service call on a hot tub that I did not install. The service guy said the problem was that stranded wire was used and that was why the tub wasn't working correctly-- even though it ran for years with the stranded wire. He insisted I change the wire. I called his boss and told him what the issue was with the tub and he knew right away what the problem was.... I don't remember the exact situation but it wasn't the stranded wire. :rotflmao:

310.106(C) Stranded Conductors. Where installed in raceways,
conductors 8 AWG and larger, not specifically permitted or
required elsewhere in this Code to be solid, shall be stranded.

 

[electrofelon]

I've pulled that in 1/2" all day long with solid or stranded. I'm not busting your chops I just notice a lot of electricians seem to think you need 3/4 and I've never understood it.


And for the record I'm a stranded guy all the way.

These are three phase full boats, so 3 would be 12 CCC which does not fit (by code) in a 1/2". But I dont hesitate to use 1/2" loaded up with 9.

 

[electrofelon]

I dont think anyone has pointed out that solid is a little cheaper, FWIW

 

[nick h]

thanks guys

 

[jap]

For those who find it difficult to land stranded wire on device screws, there are a few tricks:

Reverse-twist the strands which keeps them together better

Pinch the loop closed with needle-node pliers while tightening

Leave a ring of insulation on the tip of the wire strands

Use solid wire pigtails to join with the stranded wires

I think those who find it difficult to land stranded wires on device screws should invest in some back wired devices with compression terminals before resorting to this.

JAP>

 

[electrofelon]

I think those who find it difficult to land stranded wires on device screws should invest in some back wired devices with compression terminals before resorting to this.

JAP>

I do that sometimes. I can spin on a pigtail with my drill and make it up faster than prepping and making up stranded on a screw.

 

[electrofelon]

These are three phase full boats, so 3 would be 12 CCC which does not fit (by code) in a 1/2". But I dont hesitate to use 1/2" loaded up with 9.

Sorry that's 12 conductors , 9 CCC.

 

[jap]

Duplicate Post

 

[jap]

I do that sometimes. I can spin on a pigtail with my drill and make it up faster than prepping and making up stranded on a screw.

Hence, my suggestion of the "back wired" devices with the compression terminals.

No need for solid pigtails, prepping, or making up stranded on a screw.

JAP>

 

[ActionDave]

These are three phase full boats, so 3 would be 12 CCC which does not fit (by code) in a 1/2". But I dont hesitate to use 1/2" loaded up with 9.

I miscalculated, I was thinking of 9....:ashamed1:

I did pull eleven 12AWG in 1/2" once on an office remodel 'cause the furniture required a "clean" ground and an extra neutral.

 

[infinity]

Back to the OP, who comes up with this stuff? :slaphead:

I recently moved out to Montana and it seems like everyone uses solid wire. I'm referring to 20A and 15A circuits pulled through conduit. Several months ago someone saw me pulling stranded wire and told me it was a code violation to used stranded wire in a commercial building...i've had several people tell me the same thing since.

 

[electrofelon]

Hence, my suggestion of the "back wired" devices with the compression terminals.

No need for solid pigtails, prepping, or making up stranded on a screw.

JAP>

Yes clamps are my preference with stranded, but sometimes you don't have devices with clamps for various reasons.

 

[jaggedben]

Three pages of chat and nobody has mentioned the one section (to my knowledge) that actually talks about this.

8awg or larger in raceways must be stranded.

It's 310.3(C) in the 2020 NEC, 310.106(C) in previous codes.

 

[jusme123]

I would say 99% of my jobs specified solid for #10 and smaller, it is not hard to pull.

Roger

Load up a 1” conduit with #10 solid, and tell me it’s not a hard pull . Hard pulls are relative to the bends and pull points, ......a rookie running conduit can make for a nightmare pull.

 

[infinity]

Three pages of chat and nobody has mentioned the one section (to my knowledge) that actually talks about this.

8awg or larger in raceways must be stranded.

It's 310.3(C) in the 2020 NEC, 310.106(C) in previous codes.

It's right there in post #23.

 

[roger]

Load up a 1” conduit with #10 solid, and tell me it’s not a hard pull . Hard pulls are relative to the bends and pull points, ......a rookie running conduit can make for a nightmare pull.

We would plan our conduits accordingly and not "load them up", IOW's we would not have to derate the conductors to a lower ampacity than they are allowed at face value.

That translates to easy pulls even with solid conductors.

Roger

 

[jap]

Three pages of chat and nobody has mentioned the one section (to my knowledge) that actually talks about this.

8awg or larger in raceways must be stranded.

It's 310.3(C) in the 2020 NEC, 310.106(C) in previous codes.

And thank goodness the NEC was sharp enough to make that decision.

Otherwise it would be like shoving a groundrod through a conduit run.

JAP>

 

[roger]

It's right there in post #23.

:thumbsup:

Roger