ECN Forum Forums General Topics of the Trade General Discussion Area Bundle Temperatures

Who stands to benefit the most from that conclusion?

First, I agree with I-Wire as to the actual loading. When we de-rate, we do so based upon the size of the circuit breaker. This is just fine when you are applying this method to dedicated equipment- but, to assume that typical household convenience circuits are ALL completely loaded ALWAYS is simply silly. Yet, the code makes no distinction between a 20 amp circuit for a 19 amp refrigerator... and a 20 amp circuit that's feeding maybe 5 amps worth of TV and stereo!

I also think that there is a proposal for 08 that more closely defines "bundling," I've had a few disagreements over at the HI forums, where many seem to favor a definition a lot more inclusive than mine.

While I agree that you always have to consider the source of information presented, my point is that to many people bundling is a non-issue: I've never once met a residential j-man who had any qualms about zip-tying 10 or 15 home-runs traveling the entire length of an attic full of blow-in insulation. And most of my resi. experience is in southern states where attic temperatures can easily reach 110-115 degrees.

The situation presented in that report is basically a worse-case scenerio: Maximum load, maximum bundling, minimum ventilation.

I see value in that report because, regardless of their motives, they made me aware that there are circumstances (however remote) that can create a hazard. And there are probably more common circumstances were there is a mitigated hazard, but it's hazardous non-the-less.

It wouldn't be wise for me, or anyone, to know this and continue to ignore bundling issues out-of-hand.

-John

I do alot of residential work and I never pull more than 3 romex cables in any one 3/4" hole. I also use 3M stackers wherever I have more than 2 cables in any one run, like to a multiple switch location or homeruns in the bsmt.

I stopped reading after looking at fig 4. The 10AM wire temp is 194 degree F (90 degree C). This is amazing since the power has just been turned on after being off for over 12 hours. I expect the data is simply wrong.

(My engineering shows a 2.33" dia bundle is safe. Note I did not say hole. A 1-1/2"dia x 3-1/2" long hole, the size used in the test, is safe according to the code.)

Bob, Continous or not those two could easily be on for hours loaded above 60%. As well as many lighting circuits consisting of cans these days, or a circuit with computers and the many, many perifreals. Like this one.... Or ANY home during Chistmas or Thanksgiving, EVERYTHING IS ON! I preffer to wire homes to have it all on, all the time. As I know there will be a few times a year when they do.

As for the source, I don't think they would stand to benifit as much as companies like Irwin, Greenlee, or Lenex, the guys who make drill bits, or for those who cheap out on new ones, the guys who make files and grinders will profit. Like I said, I have been limited to two cables per hole for a long time, and before that only one.... You dont jump the wire size, just blast more holes and learn to plan your work better. Real easy to miss the nails with a 1/2"-5/8" drill bit, easier on the wrist too. And you become very articulate with it after a while.

Back on topic, I dont think it too silly to follow the rules for derating in bundles, or holes. Just because the code allows us to ignore it under 24", doesnt mean we should not take it into consideration on shorter lengths.

Mark we have had to follow the 'not bundling deal' for years here as well and I am not complaining.

As for the rest we will have to remain in disagreement.

I will have to assume you do not take any demand factors into service calcs.

Bob

Like I have said here before and on many other forums. Show me the real data. Show me the fires caused by "Bundling" romex in a dwelling. I am not about to say it won't or never did happen, just my personal wish is for somebody to back up the issue with "real" data, not lab testing. You get me lab testing AND hard real anecdotal data and then you have changed my thinking. By the way, any dumb homeowner can screw in a 150 watt light bulb into a socket that is rated for 60 watts. That causes romex to change color also and to lots of times start on fire. How about they start fixing real problems and not invent new ones.

Something is wrong.

I sure wish they would of plotted the attic temp. And then ran the whole test again with proper vented soffits and a ridge vent.
And then did it again with a power ventilator installed in the roof.

They created a heat box to manipulate the results, IMO....

I guess a proper test would have included a single cable firestopped in a standard sized hole.

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I have often wondered about wisdom of using foam in place insulation. I suspect 80% amperage would cause a problem.

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There are lots of academic problems that don't appear to cause a lot of real problems.