Wire Gauge Clarification

[albinotuba]

Hi All,

I've been hanging around this forum for a few years now, but this is my first post. I hope I'm asking this in the right sub-forum. I think this counts as an 'electrics' question.

This issue has been discussed before, but there seems to be some contention in the general case, so I'd like to ask specifically. I'm a location recording engineer, and I frequently work in theaters, concert halls, churches, and other large venues. We like to use 2-channel remote controlled preamps on stage, and run line-level or digital signals back to the control room rather than mic-level signals, because of noise and interference issues. These preamps are sitting on stage, and require about 15 watts, which they get from the closest available outlet. (They're not powered over the audio cable.) So, the question: am I required to size the power cable for the preamps based on the size of the circuit breaker (as many people have said), or am I required to size the power cable based on the load (as suggested by many other people). In other words, do I need to use 12 gauge extra-hard usage cable, or something more along the lines of 16 gauge SOOW.

Many thanks!

 

[Les]

Anyone who said the cable has to be sized to the breaker capacity is mistaken. It's the load that you want to size to.

That said, I think sound/musical equipment is a bit of a grey area... At least in my opinion. I NEVER see keyboards, effects processors, etc plugged in to SOOW on stage. Maybe the distro is, but I see all kinds of IEC cords, etc between instruments and their sources. I'm not saying it's correct or incorrect - just something that I have noted over the years.

 

[Edrick]

The building wiring is sized to breaker capacity. The devices are usually sized to device load. For example fixtures for lighting usually have very thin gauge wiring since the max wattage is 100 watts for example. Another example is PC power cords (IEC Cords) are usually 18 or 16 gauge wiring.

 

[JD]

15 watts each? Use the 16 gauge SOOW.

 

[STEVETERRY]

Hi All,

I've been hanging around this forum for a few years now, but this is my first post. I hope I'm asking this in the right sub-forum. I think this counts as an 'electrics' question.

This issue has been discussed before, but there seems to be some contention in the general case, so I'd like to ask specifically. I'm a location recording engineer, and I frequently work in theaters, concert halls, churches, and other large venues. We like to use 2-channel remote controlled preamps on stage, and run line-level or digital signals back to the control room rather than mic-level signals, because of noise and interference issues. These preamps are sitting on stage, and require about 15 watts, which they get from the closest available outlet. (They're not powered over the audio cable.) So, the question: am I required to size the power cable for the preamps based on the size of the circuit breaker (as many people have said), or am I required to size the power cable based on the load (as suggested by many other people). In other words, do I need to use 12 gauge extra-hard usage cable, or something more along the lines of 16 gauge SOOW.

Many thanks!

Here's the scoop:

1. An extra-hard -usage cable is required (type S, SO or derivatives).
2. The ampacity and gauge of the cable must be adequate to support the load.
3. Ampacity is determined by the listing requirements for a listed extension cord. Those listing requirements will also determine the largest overcurrent protective device that the extension cord can be fed from.
4. Ampacity of a "field assembled" extension cord made from listed connectors and cable is determined from NEC table 400.5(A)(1).
5. Minimum gauge of a field assembled extension cord for a 20A branch circuit is 16 AWG per NEC section 240.5(B)(4).

ST

 

[albinotuba]

16 AWG it is. Thanks all!