Control/Dimming 12/3 SOOW vs 14/3 SOOW Extensions

TheTheaterGeek

EOS Addict
Premium Member
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Is it just a complete No-No to use 14/3 SOOW for making extensions. I dont know why but my spidey sence tingles every time i see a 14/3 Cable.

Its rated for 18 Amps which give me 1980 available watts on 110v vs the 2200 that 12/3 gives you, Which to me still means 3 575 watt fixtures or 2 750 watt fixtures should be fine.

Am I just being paranoid?

Clay
 

danTt

Well-Known Member
I'd argue it falls somewhere in the gray area of code vs reality. Firstly, if used on 15 amp circuits you're fine. Secondly, If you have 110volts anywhere you probably have issues... 115 or 120 at the fixture is much more normal.

Those two things aside, there's two situations happening. Firstly is the load you are regularly putting on the cable. If your standard loads are 18-20 amps, 12 gauge is a much more sensible option. Practically, If you are one light/circuit, 14 gauge is much less of an issue. The second half (and something to keep in mind) is the rating on the breaker. According to code, all extensions must be rated to match the upstream breaker. That being said, that rule magically stops at the appliance cord. Wire leads on a source4 base are 16 gauge, and there isn't any magical OCPD built into the stage pins. Code allows this in a listed assembly, but it's unclear how much of that is based on industry lobbying and how much on practical electrical safety. (@STEVETERRY will probably clarify/correct me on this..)

In short, in a perfect situation all cable would be 12 gauge SO for 20amp stagepin use, but I wouldn't put it terribly high on the priority list of places to spend money.

This comes up relatively frequently on here, do a search for more detailed discussion.
 

Colin

Well-Known Member
First, read NEC table 400.5 again. 14/3 SOOW is going to be a 15A rating, not 18 which is for 14/2. *EDIT: nope, that would be if all three conductors were current carrying, so if one is equipment ground then column B would apply, although some textbooks on my shelf say otherwise...*

Specifically, the reason using 14/3 may be a bad idea and a violation of NEC is that if you have circuits with overcurrent protection for more than 15A, you could overload your cable well before the 20A (or whatever) breaker/fuse trips. But if you have racks of 1800W modules then 14/3 is well matched. Still, there's a higher risk of bad things happening if those cables start migrating to other spaces that are running 20A circuits.
 
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SteveB

Well-Known Member
This was covered prior, I think Steve Terry provided this response, I copied for future reference, forgot the CB link.

The minimum gauge of an extension cord (jumper) in article 520 venues is actually set by the following NEC sections:
400.13 Overcurrent Protection.
Flexible cords not smaller than 18 AWG, and tinsel cords or cords having equivalent characteristics of smaller size approved for use with specific appliances, shall be considered as protected against overcurrent in accordance with 240.5.
240.5 Protection of Flexible Cords, Flexible Cables, and Fixture Wires.
Flexible cord and flexible cable, including tinsel cord and extension cords, and fixture wires shall be protected against overcurrent by either 240.5 (A) or (B).

(A) Ampacities. Flexible cord and flexible cable shall be protected by an overcurrent device in accordance with their ampacity as specified in Table 400.5(A)(1) and Table 400.5(A)(2). Fixture wire shall be protected against overcurrent in accordance with its ampacity as specified in Table 402.5. Supplementary overcurrent protection, as covered in 240.10, shall be permitted to be an acceptable means for providing this protection.

(B) Branch-Circuit Overcurrent Device. Flexible cord shall be protected, where supplied by a branch circuit, in accordance with one of the methods described in 240.5(B)(1), (B)(3), or (B)(4). Fixture wire shall be protected, where supplied by a branch circuit, in accordance with 240.5(B)(2).

Note: [240.5(B) (1) and (2) omitted for clarity since they don’t relate to this issue on portable cables
(3) Extension Cord Sets. Flexible cord used in listed extension cord sets shall be considered to be protected when applied within the extension cord listing requirements.

(4) Field Assembled Extension Cord Sets. Flexible cord used in extension cords made with separately listed and installed components shall be permitted to be supplied by a branch circuit in accordance with the following:
20-ampere circuits — 16 AWG and larger
Above material (copyright NFPA)

So, you can see that a cable must be sized for the load it is feeding, per the ampacity tables of article 400. If it is a listed assembly, it must be used within its marked listing requirements. If it is a field assembled cord, not listed as a complete assembly, it must be a minimum 16 AWG if used on a 20A circuit. Of course, if used in a theatre, it must be type SO or another extra-hard-usage cord, unless otherwise allowed by section 520.68.

Note that a "field assembled" extension cord may actually be provided by a manufacturer who has not bothered to have it listed as a complete assembly but who has assembled it from listed parts.

Also note that a common mistake is to misapply ampacity table 520.44 and its maximum breaker size column to single circuit jumpers.
 

STEVETERRY

Well-Known Member
This was covered prior, I think Steve Terry provided this response, I copied for future reference, forgot the CB link.

The minimum gauge of an extension cord (jumper) in article 520 venues is actually set by the following NEC sections:
400.13 Overcurrent Protection.
Flexible cords not smaller than 18 AWG, and tinsel cords or cords having equivalent characteristics of smaller size approved for use with specific appliances, shall be considered as protected against overcurrent in accordance with 240.5.
240.5 Protection of Flexible Cords, Flexible Cables, and Fixture Wires.
Flexible cord and flexible cable, including tinsel cord and extension cords, and fixture wires shall be protected against overcurrent by either 240.5 (A) or (B).

(A) Ampacities. Flexible cord and flexible cable shall be protected by an overcurrent device in accordance with their ampacity as specified in Table 400.5(A)(1) and Table 400.5(A)(2). Fixture wire shall be protected against overcurrent in accordance with its ampacity as specified in Table 402.5. Supplementary overcurrent protection, as covered in 240.10, shall be permitted to be an acceptable means for providing this protection.

(B) Branch-Circuit Overcurrent Device. Flexible cord shall be protected, where supplied by a branch circuit, in accordance with one of the methods described in 240.5(B)(1), (B)(3), or (B)(4). Fixture wire shall be protected, where supplied by a branch circuit, in accordance with 240.5(B)(2).

Note: [240.5(B) (1) and (2) omitted for clarity since they don’t relate to this issue on portable cables
(3) Extension Cord Sets. Flexible cord used in listed extension cord sets shall be considered to be protected when applied within the extension cord listing requirements.

(4) Field Assembled Extension Cord Sets. Flexible cord used in extension cords made with separately listed and installed components shall be permitted to be supplied by a branch circuit in accordance with the following:
20-ampere circuits — 16 AWG and larger
Above material (copyright NFPA)

So, you can see that a cable must be sized for the load it is feeding, per the ampacity tables of article 400. If it is a listed assembly, it must be used within its marked listing requirements. If it is a field assembled cord, not listed as a complete assembly, it must be a minimum 16 AWG if used on a 20A circuit. Of course, if used in a theatre, it must be type SO or another extra-hard-usage cord, unless otherwise allowed by section 520.68.

Note that a "field assembled" extension cord may actually be provided by a manufacturer who has not bothered to have it listed as a complete assembly but who has assembled it from listed parts.

Also note that a common mistake is to misapply ampacity table 520.44 and its maximum breaker size column to single circuit jumpers.


That guy knows what he's talking about. :)

ST
 

JD

Well-Known Member
The primary reasons for keeping the gauge as 12 are more to do with:
1) Preventing someone from grabbing the wrong cable and loading it to 20 amps.
2) Some venues have it as a "house rule."
This is why so many ghost lights have long 16/3 SO cords on them. Not so much as a fixture whip, which it wouldn't be anyway at 50 feet, but because it couldn't be detached and used in an application where the current draw would be much higher than its rated listing.
 

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