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Author Topic: coiling feeder cable  (Read 2313 times)

charles strickland

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coiling feeder cable
« on: March 30, 2021, 06:04:54 PM »

  Is there a better way to coil extra feeder cable than using a figure eight ? ( when powered up )  4/4
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Frank Czar

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Re: coiling feeder cable
« Reply #1 on: March 30, 2021, 08:19:33 PM »

In over thirty years in the business I use 4/4 a lot and can only recall one time that I got noise from havening the cable in a single coil and re-doing it into a figure eight cured the noise.
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Frank Czar
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Tim McCulloch

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Re: coiling feeder cable
« Reply #2 on: March 30, 2021, 08:20:16 PM »

It gives better heat dissipation and the cris-crossing helps hold down induction heating.

Is there a particular issue you're trying to solve or just sussing out best practices?
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Kevin Graf

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Re: coiling feeder cable
« Reply #3 on: March 31, 2021, 08:30:25 AM »

It gives better heat dissipation and the cris-crossing helps hold down induction heating.
Induction heating?
If all the current is returning in the same cable, it's resistance heating.
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Chris Hindle

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Re: coiling feeder cable
« Reply #4 on: March 31, 2021, 08:50:48 AM »

Induction heating?
If all the current is returning in the same cable, it's resistance heating.
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.
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Stephen Swaffer

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Re: coiling feeder cable
« Reply #5 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.
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Steve Swaffer

Dave Garoutte

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Re: coiling feeder cable
« Reply #6 on: March 31, 2021, 12:44:34 PM »

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

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Re: coiling feeder cable
« Reply #7 on: March 31, 2021, 05:24:44 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.

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 3/4 EMT that was serving the lighting system.  I dont 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.
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Curt Sorensen

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Re: coiling feeder cable
« Reply #8 on: April 01, 2021, 02:33:19 PM »

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.
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Curt Sorensen
Madison, Wisconsin

charles strickland

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Re: coiling feeder cable
« Reply #9 on: April 01, 2021, 05:01:25 PM »

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. 
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ProSoundWeb Community

Re: coiling feeder cable
« Reply #9 on: April 01, 2021, 05:01:25 PM »


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