NEC 110.14 and highly stranded wire on oven

T

tajalir

Member
Location
Florida
Occupation
Engineer
NEC 110.14 says "conductors and terminals more finely stranded than class B or Class C must be identified for the use of finely stranded conductors." Every oven made for residential use comes with a flexible metal conduit that has finely stranded wires in it. These finely stranded wires get mated with the regular Romex wire or regular THHN (which are solid or with standard Class B or C strands) using a regular wire nut (such as Ideal Industries Wing nut, etc). The problem is that the commercially available wire nuts are not listed for use on highly stranded wire (the wire from the oven whip). The inspectors do not seem to be aware of the problem. Am I the only one who sees this problem? Has anyone else come across this issue (and found a practical solution)? Compression lugs (or butt splices) that are designed for highly stranded wires typically cover the large conductors (welding cable for generator, etc). I do not see a compression butt splice listed for #10 or #12 highly stranded wire (as is used with ovens).
 
Every oven for for residental use has flexible metal conduit with finely stranded wire? Since when? I have see a few with this but most are set up for cord and plug use. Can use a 3 wire cord for older 3 wire outlets or a 4 wire cord for newer outlets.
 
jmellc said:
Every oven for for residental use has flexible metal conduit with finely stranded wire? Since when? I have see a few with this but most are set up for cord and plug use. Can use a 3 wire cord for older 3 wire outlets or a 4 wire cord for newer outlets.
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Oven or range? Every range I've seen has terminals for a cord. Built in ovens tend to have a FMC whip which generally needs to get spliced to tapped in with the cooktop and branch circuit conductors. I haven't had a built in oven for over 30 years, and I don't think I ever took that one apart to know if it was fine strand or not. I assumed they would use AWM or MTW that is 105C.
 
tajalir said:
Am I the only one who sees this problem?
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What problem? Specs allow the use of solid or stranded wire with multiple combinations thereof. You have stranded wire, end of story. If you have a problem, you are probably not striping the conductors correctly or not letting the stranded lead the solid or not twisting the stranded. If after installing the wire nut you can tug either conductor and it doesn't come out, you have done it correctly.

-Hal
 
Chapter 9 Table 10 tells us that for #14 to #2, Class B stranding is 7 strands, and Class C stranding is 19 strands. So if the oven comes with an FMC whip with conductors with more than 17 strands (e.g. 37), then the connection in the outlet box requires a special connector per 110.14.

Cheers, Wayne
 
wwhitney said:
Chapter 9 Table 10 tells us that for #14 to #2, Class B stranding is 7 strands, and Class C stranding is 19 strands. So if the oven comes with an FMC whip with conductors with more than 17 strands (e.g. 37), then the connection in the outlet box requires a special connector per 110.14.

Cheers, Wayne
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Now find me where the wire nut specs don't allow their use with that wire. It only says they may be used with solid and stranded with no distinction between any particular stranding. So, I take that as saying they are identified as being suitable for this use per 110.14.

In my opinion 110.14 pertains to setscrew, pressure terminals and crimp lugs.

-Hal
 
tajalir said:
Compression lugs (or butt splices) that are designed for highly stranded wires typically cover the large conductors (welding cable for generator, etc). I do not see a compression butt splice listed for #10 or #12 highly stranded wire (as is used with ovens).
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Do you have a photo of the highly stranded wire?
 
hbiss said:
Now find me where the wire nut specs don't allow their use with that wire.
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That's not what 110.14 says. It says that for other than Class B and Class C, the connector "shall be identified for the specific conductor class or
classes." So if the whip conductors have class K stranding, then the wirenut packaging needs to say "suitable for class K stranding" or something like that.

Cheers, Wayne
 
hbiss said:
Now find me where the wire nut specs don't allow their use with that wire. It only says they may be used with solid and stranded with no distinction between any particular stranding.
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Look at the last part of the parent text of 110.14.
Connectors and terminals for conductors more finely stranded than Class B and Class C stranding as shown in Chapter 9, Table 10, shall be identified for the specific conductor class or classes.
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I am not aware of any wire nut that has been identified for use with finely stranded conductors.
 
don_resqcapt19 said:
Look at the last part of the parent text of 110.14.

I am not aware of any wire nut that has been identified for use with finely stranded conductors.
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I work with finely stranded (Type W) a ton. It doesn't seem the Code covers the use of ferrules in regular B/C set screw connectors, which is common practice and works well. I can provide photos.

Mark
 
I am just curious with regard to a "wirenut" and class K stranding...... Isnt SO cord or lamp cord ( from a pendant luminaire), also a type K stranding? If so dont we all use a "wirenut" to connect these conductors to building wiring?

Again just curious persuant to the current discussion.


Howard
 
busman said:
It doesn't seem the Code covers the use of ferrules in regular B/C set screw connectors,
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That would be a listing and labeling issue...only permitted if the manufacturer has specified that method of termination for finely stranded conductors. At one time SquareD had an instruction that showed wrapping the finely stranded conductors in copper foil for terminating in set screw connectors. Not sure if they still say that.
 
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