Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums > AC Power and Grounding

coiling feeder cable

<< < (2/4) > >>

Stephen Swaffer:
Take a look at conduit conductor count deratings to get a picture of how quickly heat dissipation can become an issue.  Conductor ampacities are based on insulation temperature ratings-most of these are high enough to make a hand warmer.  Bundle a bunch together and you have lots of heat.   Just common sense-if you think about the physics behind the rules in the NEC.  Just like thinking about the physics involved in setting up a sound system.

Dave Garoutte:

--- Quote from: Chris Hindle on March 31, 2021, 08:50:48 am ---But also induction heating to the closely coupled loops of cable.... as I understand it.
At a "big show" I teched one winter last century, the over/under 50 odd feet of 400A feeder made a nice hand warmer. The feeder itself (away from the loop) was cool to the touch.
Chris.

--- End quote ---
A stacked coil of 'heater' wire will have way less surface area to dissipate said heat compared to a single strand laid out.

Erik Jerde:

--- Quote from: Stephen Swaffer on March 31, 2021, 12:36:20 pm ---Take a look at conduit conductor count deratings to get a picture of how quickly heat dissipation can become an issue.  Conductor ampacities are based on insulation temperature ratings-most of these are high enough to make a hand warmer.  Bundle a bunch together and you have lots of heat.   Just common sense-if you think about the physics behind the rules in the NEC.  Just like thinking about the physics involved in setting up a sound system.

--- End quote ---

I can attest to that.  I was climbing in an attic space over a stage once and I laid hands on a very warm piece of 3/4Ē EMT that was serving the lighting system.  I donít know how many circuits or what the conduit fill was but it was just a hair uncomfortable to hold onto.  Fortunately there was other structure around more appropriate to use for climbing.

Curt Sorensen:
A friend toured with Brit Row and was taught to alternate a coil (loop) and an eight. He said it evened out the build-up from the cross-overs when only figure eights are used. I assume every other coil is over-under. Luckily I don't deal with much bundled feeder these days, so no personal experience with that approach.

charles strickland:
I asked the question mainly for best practice reasons. on occasion I have an extra 20 ft or so cable to deal with, heat build up was my main concern.  Thank you for the advice. 

Navigation

[0] Message Index

[#] Next page

[*] Previous page

Go to full version