Wire size reduction for branch circuits

don_resqcapt19

Moderator
Staff member
Location
Illinois
If you are using smaller than 14 AWG I agree, it must be fixture wire, my point all along here has been that use of tap conductors is not limited to fixture wire only.
After taking another look the rules in 240.5(B)(2) included conductors 14 and larger. I think the code language in 240.5(B)(2) needs fixing. As I re-read it, you must use fixture wire anytime you are protecting the conductors at the ampacities listed in that section. Some types of fixture wire is available in 12 and 14 AWG, but I think the code needs fixing here. Not sure there is any reason to have the OCPD rating based on the type of insulation on the conductors. The insulation type is the only real difference between other conductors of the same size and fixture wire.
 

kwired

Electron manager
Location
NE Nebraska
After taking another look the rules in 240.5(B)(2) included conductors 14 and larger. I think the code language in 240.5(B)(2) needs fixing. As I re-read it, you must use fixture wire anytime you are protecting the conductors at the ampacities listed in that section. Some types of fixture wire is available in 12 and 14 AWG, but I think the code needs fixing here. Not sure there is any reason to have the OCPD rating based on the type of insulation on the conductors. The insulation type is the only real difference between other conductors of the same size and fixture wire.
Why? 240.5(B)(2) is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." If there is such a rule on other "tap conductors" to a luminaire they it can certainly be in some other section, this one is or fixture wire. I didn't find any specific general rule for tap conductors that are other than fixture wire or cord, but did find the couple specific applications I mentioned code sections for.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Why? 240.5(B)(2) is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." If there is such a rule on other "tap conductors" to a luminaire they it can certainly be in some other section, this one is or fixture wire. I didn't find any specific general rule for tap conductors that are other than fixture wire or cord, but did find the couple specific applications I mentioned code sections for.
(B)(2) is specific to fixture wire. (B)(1), (B)(3) and (B)(4) apply to flexible cords. (A) covers the requirements for flexible cable.
I see nothing in the other sections that you cited that act to change the requirements of 240.5.
 

kwired

Electron manager
Location
NE Nebraska
Why? 240.5(B)(2) is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires." If there is such a rule on other "tap conductors" to a luminaire they it can certainly be in some other section, this one is or fixture wire. I didn't find any specific general rule for tap conductors that are other than fixture wire or cord, but did find the couple specific applications I mentioned code sections for.
(B)(2) is specific to fixture wire. (B)(1), (B)(3) and (B)(4) apply to flexible cords. (A) covers the requirements for flexible cable.
I see nothing in the other sections that you cited that act to change the requirements of 240.5.
Correction, 240.5 is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires."

If your tap conductor is not fixture wire flexible cord or flexible cable, nothing in 240.5 applies to it, is what I have been trying to say all along.

Does AC or MC cable count as flexible cable? If so then I take back some of what I said. How about THHN in flexible metal conduit? Supposed to be a raceway not a cable?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Correction, 240.5 is titled "Protection of Flexible Cords, Flexible Cables, and Fixture Wires."

If your tap conductor is not fixture wire flexible cord or flexible cable, nothing in 240.5 applies to it, is what I have been trying to say all along.

Does AC or MC cable count as flexible cable? If so then I take back some of what I said. How about THHN in flexible metal conduit? Supposed to be a raceway not a cable?
Correct, if it is not one of those, nothing in the section applies. However that means other than the very very limited branch circuit taps permitted in Article 210, those other conductors have to be protected at their ampacity.

AC and MC are not flexible cables, and neither is THHN. Flexible cables are those found in Table 400.4.
 

kwired

Electron manager
Location
NE Nebraska
Correct, if it is not one of those, nothing in the section applies. However that means other than the very very limited branch circuit taps permitted in Article 210, those other conductors have to be protected at their ampacity.

AC and MC are not flexible cables, and neither is THHN. Flexible cables are those found in Table 400.4.
So is it acceptable to use a fixture tap that is THHN in flex or AC/MC cable or must you run same size as branch circuit when using those methods?

I think 410.117 is one place that specifically says you can, though that is a specific situation and not a general thing there.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
So is it acceptable to use a fixture tap that is THHN in flex or AC/MC cable or must you run same size as branch circuit when using those methods?

I think 410.117 is one place that specifically says you can, though that is a specific situation and not a general thing there.
In my opinion if you want to protected the fixture tap wires at the ampacities specified in 240.5(B)(2) the conductors must be fixture wire and not THHN.
 
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