The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Calling all Non-US members!! (Non-US only)
by aussie240
Yesterday at 02:39 AM
Photo Upload Tutorial
by DanK
12/06/16 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Trumpy 6
Who's Online
0 registered (), 170 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#7146 - 01/24/02 01:23 PM sub panel feeder wire sizes......
duanet Offline
Junior Member

Registered: 12/02/01
Posts: 7
Hi,
I am installing a new 125 Amp sub panel 65 feet away from a new 200 amp service. The sub is located in the same shop as the main panel. Do i need to pull a separate grounding conductor for the sub or can the EMT between the main and the sub be used for the grounding bond? I ask as i would like to use 1-1/4 EMT which will only allow three #1 copper conductors.
(per conduit fill table 3B)
Thus allowing 2-#1 lines and a common max.
If i have to pull a separate #6 ground i would have to step up to the 1-1/2 EMT. Basically i wish to know if on a sub panel situation such as this is it allowed to use the EMT conduit as the ground rather than a separate conductor?

thanks

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#7147 - 01/24/02 02:22 PM Re: sub panel feeder wire sizes......
dana1028 Offline
Member

Registered: 01/09/02
Posts: 163
Loc: San Carlos, CA
I'm now looking at Appendix C of the 1999 NEC, pg. 585 - THHN #1...4 conductors (#1 size) are allowed in 1-1/4" EMT

Top
#7148 - 01/24/02 02:28 PM Re: sub panel feeder wire sizes......
duanet Offline
Junior Member

Registered: 12/02/01
Posts: 7
You may want to check again as my NEC book Table 3B (maximum # of conductors in trade sizes of conduit or tubing) states that a maximum of 3 #1 THHN in 1-1/4

Top
#7149 - 01/24/02 02:48 PM Re: sub panel feeder wire sizes......
Tom Offline
Member

Registered: 01/01/01
Posts: 1069
Loc: Shinnston, WV USA
Where the heck is table 3B?

Table C1 on page 585 is the correct one to use & as dana1028 pointed out 1 1/4" emt is good for 4 #1's.

You don't usually need to pull in the equipment ground, but many electricians prefer to include one in all their conduit work.
_________________________
Few things are harder to put up with than the annoyance of a good example.

Top
#7150 - 01/24/02 02:51 PM Re: sub panel feeder wire sizes......
duanet Offline
Junior Member

Registered: 12/02/01
Posts: 7
Table 3B is in chapter 9 (tables and examples) page 750 of 1990 NEC

Top
#7151 - 01/24/02 05:54 PM Re: sub panel feeder wire sizes......
Anonymous
Unregistered


duanet,

Its time to invest in a new NEC book.

Top
#7152 - 01/24/02 07:37 PM Re: sub panel feeder wire sizes......
eman1963 Offline
Member

Registered: 01/24/02
Posts: 22
Loc: rhode island
i would use the 1 1/4 emt as the ground and run only 3 conductors

Top
#7153 - 01/24/02 07:38 PM Re: sub panel feeder wire sizes......
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
What size breaker are you installing ?

Top
#7154 - 01/25/02 03:56 PM Re: sub panel feeder wire sizes......
dana1028 Offline
Member

Registered: 01/09/02
Posts: 163
Loc: San Carlos, CA
BTW - Appendix C, pg. 585 does say 4 #1 are allowed in 1-1/4" EMT; however if you do the arithmetic from Table 4 & Table 5 (EMT usable space & area of THHN tables)you cannot use 4 #1s in 1-1/4" EMT.

However, even though you are allowed to use the EMT as the EGC, I highly recommend you do pull the #6 (the arithmetic works) as your EGC - don't trust the EMT connection over the years to be maintained and work when needed in the event of a fault.

Top
#7155 - 02/05/02 08:03 PM Re: sub panel feeder wire sizes......
3rd degree Burns Offline
Member

Registered: 02/04/02
Posts: 38
Loc: Dallas, Texas, USA
I have to agree with Dana, don't trust conduits to carry the ground as the years progress...I've already seen far too many lost grounds from installations 15 to 30 years old. Go ahead and pull it, you won't regret it later.

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals