ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
This Old House
by johno12345. 05/26/18 12:44 PM
Extension cords
by LongRunner. 05/25/18 12:19 PM
Fire source!
by LongRunner. 05/25/18 01:49 AM
Alternative income sources
by gfretwell. 05/24/18 10:07 PM
Furnace igniter leaking noise to stereo
by geoff in UK. 05/23/18 01:18 PM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
0 registered members (), 21 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
250-122 (b) #196816
10/28/10 07:41 PM
10/28/10 07:41 PM
M
mikesh  Offline OP
Member
Joined: Jun 2006
Posts: 613
Victoria, BC, Canada
I am doing a bit of research for a Canadian rule on bonding conductor sizing.

NEC article 250.122 B says bonding wire (equipment ground) must increase with current carrying wires per some ratio.

I have some older references to 250.95 from soares book on grounding and the green book which must be in a code older than 2002.

Anyone have an older book that has an article or table 250.95?
What did it say? Was there a Table associated with it?

2017 / 2014 NEC & Related Books and Study Guides
Re: 250-122 (b) [Re: mikesh] #196821
10/28/10 08:38 PM
10/28/10 08:38 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,225
Estero,Fl,usa
This is from the 96 code
Let's see if this works wink


Quote

250-95. Size of Equipment Grounding Conductors.

Copper, aluminum, or copper-clad aluminum equipment grounding conductors shall not be less than shown in Table 250-95.

Where conductors are run in parallel in multiple raceways or cables, as permitted in Section 310-4, the equipment grounding conductor, where used, shall be run in parallel. Each parallel equipment grounding conductor shall be sized on the basis of the ampere rating of the overcurrent device protecting the circuit conductors in the raceway or cable in accordance with Table 250-95.

Where conductors are adjusted in size to compensate for voltage drop, equipment grounding conductors, where required, shall be adjusted proportionately according to circular mil area.

Where a single equipment grounding conductor is run with multiple circuits in the same raceway or cable, it shall be sized for the largest overcurrent device protecting conductors in the raceway or cable.

Where the overcurrent device consists of an instantaneous trip circuit breaker or a motor short-circuit protector, as allowed in Section 430-52, the equipment grounding conductor size shall be permitted to be based on the rating of the motor overload protective device but not less than the size shown in Table 250-95.

Exception No. 1: An equipment grounding conductor not smaller than No. 18 copper and not smaller than the circuit conductors and part of fixture wires or cords in accordance with Section 240-4.

Exception No. 2: The equipment grounding conductor shall not be required to be larger than the circuit conductors supplying the equipment.

Exception No. 3: Where a raceway or a cable armor or sheath is used as the equipment grounding conductor, as provided in Sections 250-51, 250-57(a), and 250-91(b).

Table 250-95. Minimum Size Equipment Grounding Conductors for Grounding Raceway and Equipment
[Linked Image]


Greg Fretwell
Re: 250-122 (b) [Re: gfretwell] #196823
10/28/10 10:04 PM
10/28/10 10:04 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 6,967
Brick, NJ USA
Doug:
I just checked the 1981 NEC (Handbook) and 250.95 is verbatum to what Greg inserted above, without the following:

"Where the overcurrent device consists of an instantaneous trip circuit breaker or a motor short-circuit protector, as allowed in Section 430-52, the equipment grounding conductor size shall be permitted to be based on the rating of the motor overload protective device but not less than the size shown in Table 250-95."

Table 250.95 is identical.

I have older NECs at the work office, I'll attempt to remember to check it as far back as I can Fri. (I hope)


John
Re: 250-122 (b) [Re: HotLine1] #196824
10/28/10 10:14 PM
10/28/10 10:14 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,225
Estero,Fl,usa
It is the same in 75 except they say MCM, not kcmil


Greg Fretwell

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
renosteinke
renosteinke
Blue Collar Country
Posts: 5,316
Joined: January 2005
Show All Member Profiles 
Top Posters(30 Days)
twh 7
Popular Topics(Views)
246,943 Are you busy
184,345 Re: Forum
173,548 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.021s Queries: 15 (0.004s) Memory: 0.9617 MB (Peak: 1.0961 MB) Zlib enabled. Server Time: 2018-05-28 03:00:33 UTC