LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
with small sheet-metal screws.
12/2 UF wire in 1/2" PVC
- Thread starter Btbamfan4
- Start date
- Status
with small sheet-metal screws.
Btbamfan4
Member
- Location
- Monroe, NC
- Occupation
- Electrician
I can zip tie uf wire to the beams? Good to know. Never ran across this situation before. Use to wiring houses with general crawls and slabs
- Location
- New Jersey
- Occupation
- Journeyman Electrician
There are two separate issues one is fill based on the size of the conductor and the raceway the other is derating due to more than 3 CCC's in the raceway. They really have nothing to do with each other.
Btbamfan4
Member
- Location
- Monroe, NC
- Occupation
- Electrician
I still dont understand the 3 CCC you keep mentioning. are you saying the ground is a current carrying conductor?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
He is not saying that you have 3 CCC, he is saying that derating starts at 4 CCC. And the EGC is not a CCC at all. The neutral in an MWBC typically is a CCC, but under specific circumstances (e.g. full boat) it is still not counted for derating purposes.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
It is heat related. The number impacts the way the way the conductors twist and turn around each other in the conduit. After 3 conductors it becomes likely that 1 conductor may always find itself stuck below the other conductors and therefore not be able to dissipate heat as well.
As far as using the widest part of the elliptical cable, as infinity said, it is about the cable being free to turn and twist as it is pulled through the conduit without being damaged.
Can you replace at least 1 TA with a cable clamp, so you have a bunch of glued together physical protection items rather than a conduit run?
Btbamfan4
Member
- Location
- Monroe, NC
- Occupation
- Electrician
I could. I have 2 junctions in the crawl at fs boxes If i put 4 in (2 on each box) that would make every end breathable. Would that work?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
What do you mean by breathable?
Btbamfan4
Member
- Location
- Monroe, NC
- Occupation
- Electrician
How fa
How far of a gap should I leave between each pipe and the fs box? Enough to get a strap within 8 inches?
Btbamfan4
Member
- Location
- Monroe, NC
- Occupation
- Electrician
I thought the point of having a cable clamp was to help dissipate heat since it would be enclosed. I'm confused. I'm trying to reply to so many different post lol
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
12/2 uf is 463X183 mils according to southwire. So it is .07 sq. in which means it should fit. I used to sleeve 2-12/2 nm in 1/2" but that was a bare
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Code mixes everything up into a 'simplified' set of rules to follow. If you look for corner cases you will break the physics of things and just get confused.
For example, code requires you to 'derate' if you have too many conductors in a single raceway. But there is no allowance made for the size of the raceway. You could have ten #12 conductors in a 1" EMT or a 6" GRC and code would have the exact same derating requirements.
I believe that the main reason for conduit fill requirements is the issue of being able to insert conductors. Nothing to do with heating or air flow.
IMHO in the situation that you described, the PVC and the UF were actually a good combination. What I suggest you might have done differently was to run the UF from the first box stapled or whatever to get from the box down to the metal below the trailer, then simply gone into a PVC sleeve for the length of the run, then exited the PVC and returned to stapled fastening going to the second box.
-Jon
For example, code requires you to 'derate' if you have too many conductors in a single raceway. But there is no allowance made for the size of the raceway. You could have ten #12 conductors in a 1" EMT or a 6" GRC and code would have the exact same derating requirements.
I believe that the main reason for conduit fill requirements is the issue of being able to insert conductors. Nothing to do with heating or air flow.
IMHO in the situation that you described, the PVC and the UF were actually a good combination. What I suggest you might have done differently was to run the UF from the first box stapled or whatever to get from the box down to the metal below the trailer, then simply gone into a PVC sleeve for the length of the run, then exited the PVC and returned to stapled fastening going to the second box.
-Jon
FionaZuppa
Senior Member
- Location
- AZ
- Occupation
- Part Time Electrician (semi retired, old) - EE retired.
Yep, both heat and chafing are accounted for.
FionaZuppa
Senior Member
- Location
- AZ
- Occupation
- Part Time Electrician (semi retired, old) - EE retired.
I am not sure it's a mixup. There is no pratical application where you'll have say 25 CCC's and the conduit radius is so large that they all lay flat in the conduit. The common scenario is that some CCC's will be surrounded by others thereby creating a heat "issue", hence derating. Why the # 3, I dunno.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
And they're two completely different requirements that have nothing to do with each other.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
sounds good.
In this case your PVC becomes a support and protective sleeve, not a raceway/conduit.
Btbamfan4
Member
- Location
- Monroe, NC
- Occupation
- Electrician
That helps out alot. Greatly appreciate the advice. Thanks to everyone who shared their knowledge!
FionaZuppa
Senior Member
- Location
- AZ
- Occupation
- Part Time Electrician (semi retired, old) - EE retired.
That's what is mentioned a few times. Two separate issues wrapped up into the same "fill rules". And at least from my perspective, they do have something to do with each other, at least within that NEC version, because the fill rules tell the reader s/he must run some math on two things when sticking wires and cables in a raceway/conduit.
readydave8
re member
- Location
- Clarkesville, Georgia
- Occupation
- electrician
sometimes there is a gap between top of beam and underbelly so cable can go over beam instead of under
and wooden wedges top of piers to staple to
does not answer your question but may explain why I don't know the answer
and wooden wedges top of piers to staple to
does not answer your question but may explain why I don't know the answer
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
,463 major diameter, .463 x .463 x.7854= area of UF cable=.1684
1/2 schd 40 @53%=.131
no good
1/2 schd 40 @53%=.131
no good
- Status