ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Where is Everyone?
by luckyshadow - 11/21/21 10:14 AM
It's been an interesting career
by The Watt Doctor - 11/19/21 09:56 AM
Well I am back to stay (nearly 6 years)
by The Watt Doctor - 11/19/21 09:17 AM
Motor Load Relationships Between Fans and Pumps
by The Watt Doctor - 11/18/21 09:24 AM
GFCI's pops in large numbers
by dsk - 11/05/21 06:45 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 24 guests, and 22 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#205504 02/27/12 11:02 PM
Joined: Jul 2002
Posts: 241
S
SJT Offline OP
Member
There is an old (1960's) unfused 600 amp disconnect fed with parrallel 500's.
We are looking to replace the switch. I was wondering what type of insulation was used back then. I should send a picture of the wire.
For an amperage rating of these wires, can I use the left coloumb (310.15(B)(16) in the NEC (60c-TW), to play it safe?
I know that table will give it a lower rating, plus I have to derate 70%. It's 6" gal, with 6-500's, and 2-250's for the nuetral.
Thanks, SJT

SJT #205508 02/28/12 01:41 AM
Joined: Jul 2004
Posts: 9,672
Likes: 7
G
Member
TW is a good guess.


Greg Fretwell
SJT #205511 02/28/12 10:33 AM
Joined: Oct 2006
Posts: 745
E
Member
Most of the larger sizes that I ever saw from that era were either THW or RHHW. I don't remember seeing type TW in anything above #10, but I'm not saying that it didn't exist.


---Ed---

"But the guy at Home Depot said it would work."
SJT #205515 02/28/12 12:25 PM
Joined: Jul 2004
Posts: 9,672
Likes: 7
G
Member
I guess I was really just trying to establish a column in 310.16
I agree the insulation did not look like TW. I used to have a piece of 750 MCM under the seat of my car as a persuader in serious social situations.


Greg Fretwell
SJT #205521 02/28/12 08:35 PM
Joined: Apr 2002
Posts: 7,283
Likes: 3
Member
I still have a piece of 600THHN for the persuader; hopefully it will just stay where it is.

I remember an industrial demo job that had 500 RHHW, and some 'newer' THW. Both had the same values at the scrap yard!!


John
SJT #205523 02/29/12 12:08 AM
Joined: Jul 2004
Posts: 9,672
Likes: 7
G
Member
I don't know where that piece of 750 is now. I gave it to my old buddy who was a cable splicer for Ma Bell. He planned on stripping it, dipping the fluxed strands in a lead pot and making a big lead head mace like you make a candle.


Greg Fretwell
SJT #205525 02/29/12 02:08 AM
Joined: Sep 2002
Posts: 913
Likes: 1
N
Member
There is a building locally, that has 350 MCM TW (260A) for the main w/ 400A fuses in the main switch, the load regularly exceeded the rating of those conductors in the summer.


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

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

 

Member Spotlight
timmp
timmp
Leo, IN, USA
Posts: 28
Joined: June 2004
Top Posters(30 Days)
Trumpy 5
dsk 3
Popular Topics(Views)
286,157 Are you busy
218,583 Re: Forum
204,800 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5