Tv electricians

[physis]

Re: Tv electricians

That sort of attempts to turn the question into engineering Pierre. In which case there should be something in the code so that Bob and I don't become engineers by virtue of code omission.

Bob, I'm finding you taking an atypical position on this. Usually you'd be ripping these guy for trying to modify code through interpretation.

 

[physis]

Re: Tv electricians

I'm playing Devil's advocate myself.

Let's pressume that when there's no definition in the NEC we use some dictionary interpretation.

Mine says:

Bun٠dle 1. any number of things tied, wrapped, or otherwise held together.

[Bundeled (-d'ld), Bundling], 1. to make into a bundle; wrap or tie together.

Those are the first items under the definition too. Means they're most common.

Edit: I left out a letter.

[ May 30, 2005, 03:23 PM: Message edited by: physis ]

 

[iwire]

Re: Tv electricians

Originally posted by physis:
Bob, I'm finding you taking an atypical position on this. Usually you'd be ripping these guy for trying to modify code through interpretation.

That would be true if I did not think this was a reasonable interpretation of the NEC.

I think a lot of the derating rules are made intentionally broad to cover all situations.

If I put twelve 14 AWG THHNs in a 1/2" raceway derating rules apply and I think we all agree that they should. With 12 in a 1/2" some are sure to be surrounded by other conductors.

If I put the same twelve 14 AWG THHNs in a 4" raceway derating rules apply.

Should the derating rules apply here? The wires will not be tightly packed and the metal raceway will work as a heat sink.

It does not need to make sense, it is code.

 

[roger]

Re: Tv electricians

Originally posted by iwire:


It does not need to make sense, it is code.

Bob you are the man, no truer words have ever been spoken.

For some reason 210.52(E) comes to mind

Roger

[ May 30, 2005, 08:38 PM: Message edited by: roger ]

 

[physis]

Re: Tv electricians

Bob and Roger, excuse me a second.

Conductors confined in a 4 inch diameter space aren't comperable to cables in open air either by code or by physics.

The coduit may act as a heat sink but the air and insulation inbetween the conductor and the conduit do just the opposite. They act as thermal insulators.

That's kind of why conduit is treated differently than cable.

 

[roger]

Re: Tv electricians

Sam, I didn't see where Bob said you could use open air values. I just liked his profound and so true statement.

Roger

 

[iwire]

Re: Tv electricians

Originally posted by physis:
The conduit may act as a heat sink but the air and insulation inbetween the conductor and the conduit do just the opposite. They act as thermal insulators.

I disagree.

Besides we do not use the 'free air' table for cable assembles.

 

[roger]

Re: Tv electricians

Okay Bob, here we are again.

Roger

 

[physis]

Re: Tv electricians

I didn't see where Bob said you could use open air values.

I don't see where I said that either.

I said something about "cables" in open air not acting like conductors in a conduit.

So anyway, just for fun, what's the comparison?

And happy memorial day too guys.

 

[roger]

Re: Tv electricians

Originally posted by physis:

So anyway, just for fun, what's the comparison?

And happy memorial day too guys.

There is no comparison, and thank you.

Sam, I hope you are having a nice and safe Holiday too.

Roger

 

[iwire]

Re: Tv electricians

Sam imagine three loaded 12 AWGs in 1/2" EMT

Now imagine the same thing done in NM.

Same load on both methods, I will bet you the conductors in the EMT run cooler.

If you are overclocking your PC and need to make a kicking heat sink for your processor which matrial will work better?

The plastic that makes the sheath of NM or steel as EMT is made from?

Or how about this, if you where out in the cold which would make a better blanket, steel or plastic.

 

[physis]

Re: Tv electricians

Alright, alright, I'm with you Bob.

Are you gonna space that heat sink even a thirty second of an inch off the processor?

If you did it wouldn't help much.

Edit: After how many minutes or hours do you expect the air in the EMT to remain as cool or cooler than the ambient air around the cable?

[ May 30, 2005, 09:29 PM: Message edited by: physis ]