Code Question

[Jeffrey R. Pope]

Can anyone provide me with a reference? I'm on an inspection and haven't had the opportunity to look this up yet.

What section/reference requires all conductors of a single circuit to be contained within a single conduit?

Thanks in advance.

[Michael Larson]

300.3 Conductors

• (B) Circuit Conductors Grouped Together.
All conductors of a circuit must be installed
in the same raceway, cable, trench, cord,
or cable tray, except

[Jeffrey R. Pope]

Thanks Mike.

[Jim Port]

There is an exception for circuits run in non-metallic methods.

[Jeffrey R. Pope]

Originally Posted by Jim Port

There is an exception for circuits run in non-metallic methods.

Yes, I know. This was in two runs of side-by-side PVC, buried and supplying the pool equipment panel about 60 feet away.

I had never seen this done before, so I wanted to check the reference before I left the property. One PVC contained 1 ungrounded conductor and the neutral, while the other PVC contained the other ungrounded conductor and the EGC.

[Robert Meier]

That is also a violation of 300.20(A).

300.20 Induced Currents in Ferrous Metal Enclosures or Ferrous Metal Raceways.
(A) Conductors Grouped Together. Where conductors carrying alternating current are installed in ferrous metal enclosures or ferrous metal raceways, they shall be arranged so as to avoid heating the surrounding ferrous metal by induction. To accomplish this, all phase conductors and, where used, the grounded conductor and all equipment grounding conductors shall be grouped together.

[Sean Fogarty]

To shed light on my ingonrance, with the exception of it not being code, what is the potential concern with running the wires in that manner?

[Jim Port]

The magnetic fields will cause heating.

[Jeffrey R. Pope]

Originally Posted by Robert Meier

That is also a violation of 300.20(A).

I read that, but didn't believe that to be at issue.

This was new construction, and the electrical inspector "assured" me this is acceptable after I questioned it. Based on the exception of 300.3, I conceded. After all, he does have the last word.

I didn't think 300.20 was at issue because the conductors don't really "travel through" separate metallic enclosures. I guess I can see the potential for a small portion of the box to become heated.

So (Robert and Jim), do you guys see this as an improper installation?

[Jim Port]

I would not do it this way and never thought about this before. I believe this meets the exception in 300.3. As far as 300.20, once the conductors enter the enclosure they could be considered grouped. I would like to hear other opinions on this.

[Robert Meier]

You're correct I quoted the wrong section It should be 300.20(B). 300.3(B)(3) directs you to 300.20(B).

300.3(B)(3) Nonferrous Wiring Methods. Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, shall comply with the provisions of 300.20(B). Conductors in single-conductor Type MI cable with a nonmagnetic sheath shall comply with the provisions of 332.31. Conductors of single-conductor Type MC cable with a nonmagnetic sheath shall comply with the provisions of 330.31, 330.116, and 300.20(B).

300.20(B) Individual Conductors. Where a single conductor carrying alternating current passes through metal with magnetic properties, the inductive effect shall be minimized by (1) cutting slots in the metal between the individual holes through which the individual conductors pass or (2) passing all the conductors in the circuit through an insulating wall sufficiently large for all of the conductors of the circuit.

[Jim Port]

Robert, as I understand 300.20 it would apply to things like K&T entering a metallic junction box or enclosure.

[Robert Meier]

Originally Posted by Jim Port

Robert, as I understand 300.20 it would apply to things like K&T entering a metallic junction box or enclosure.

Yes, but 300.3(B)(3) sends you to 300.20(B) which, in the case of the photo, would require a slot to be cut between the raceways. Since in the photo you have conductors run in different raceways then the provisions of 300.20(B) would apply.

[Jim Port]

After reading both together I agree a slot is needed.

[Robert Meier]

Yes it's a bit confusing because when you read 300.20(B) as a standalone requirement it doesn't seem to fit the installation in question. Once you add 300.3(B)(3) into the mix it directs you to the requirement for a slot.