ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Unusual Well Pump Switch Failure
by sabrown - 10/28/20 04:31 PM
Look at this mess...
by InspectorE - 10/27/20 09:09 PM
New tool
by gfretwell - 10/24/20 11:09 AM
Where is Everyone?
by Bill Addiss - 10/17/20 07:04 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
1 registered members (Scott35), 18 guests, and 12 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Derate this........ #77897 07/20/01 11:39 AM
Joined: Jul 2001
Posts: 7
J
Jim W Offline OP
Junior Member
I agree the code teaches derating, but in real world practice I have seen many ignore it. I mean you would have to run multiple conduits for simple things like wall outlets ect. Matter of fact in code class many working electricains were just as shocked as I was by how much you must derate. Looking backwards at that point I saw several projects not derated admittley out of my own ignorance, the wire fill for conduit is useless when you cross it with the derating table, your wires are rated down so much long before the fill is reached (when dealing with smaller conductors #14-10#).
That said on any future designs I will derate for safetys sake!, but I to tryed explaining this to my boss and it was just easyer to run 2" emt and stuff it full. Sorry guys but thats what happened and does happen. Like I say I now know better.
Also running seperate conduit for control wiring is like pulling teeth.
When I talk about control wiring I mean, from thermostat to relays and so on, I know its good to put them in a seperate conduit yet..., I work commercail, radio, tv, broadcast stations, better yet run the suckers in the open much quicker if below 60 volts throw them across that false ceiling. Strap them to the outside on the emt along with the cat 5 ! Ha Ha Ha.
Ive seen 2" emt stuffed with 30 wires no derating.
Like I say the fill tables are a joke, if you derate why would you fill that conduit up? You would not. Run 10 3/4" pipes instead that way you can have 3-6 wires in a stick. Ha Ha would'nt that look nice. And remember you can not use conduit to support conduit! Those 10 pipes be hanging all over the place!
Little off the wall tonight but you get the idea, about what a shock these derating tables are.

2017 / 2014 NEC & Related Books and Study Guides
Re: Derate this........ #77898 07/20/01 05:02 PM
Joined: Dec 2000
Posts: 127
G
gpowellpec Offline
Member
Jim,
I came up doing industrial work. Did a lot of Motor Control Centers in my younger days and wondered why the motor feeders were all run in individual conduits (RGS or Aluminum) instead of trunk runs. When I came to the requirement for derating due to number of conductors in raceway while studying the Code it became obvious. By the time you upsize the conductors to run one trunk for a number of circuits, then upsize the conduit for the oversize wires you will have a lot of money in extra copper, and the larger sizes of conduit increase in price at a greater proportion than the volume does. Not to mention the labor for the extra weight of the copper and conduit. And fittings. How many 3/4 inch LBs can you buy for the price of one 2 inch LB?

Re: Derate this........ #77899 07/20/01 07:17 PM
Joined: Dec 2000
Posts: 4,283
electure Offline
Member
There certainly is a point of diminishing returns on the "pipe stuffer" method.
Jim, I think one of these days your boss will get burned by an inspector, or worse.
If one of his jobs cooks, and he loses $$, maybe he'll wake up.
. Best of luck to you, & kudos for trying to do the right thing.

Re: Derate this........ #77900 07/20/01 09:49 PM
Joined: Oct 2000
Posts: 5,389
S
sparky Offline
Member
the diligent sparky, or so i was told, that meets the code MINIMUM eats best.

your boss eats best Jim.

but just for now....

in my idealistic fanatsy 5 star NEC inspectors will be hiding behind every corner to take him down.


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
CDS
CDS
Nicholson Ga
Posts: 34
Joined: June 2006
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
271,034 Are you busy
205,039 Re: Forum
193,154 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3