ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
0 members (), 255 guests, and 16 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Dec 2005
Posts: 2
D
damoski Offline OP
Junior Member
Prelude:
All ground conductors must be of sufficient size to trip the circuit breaker or fuse of the circuit that it protects, without overheating 15 amp circuit 15 amp wire, 20 amp circuit 20 amp wire. Refer to tables 250-94 and table 250-95, 1987 NEC (National Electrical Code).

Question:
I often combine two 14/2 cables from different circuits (15A fuses) in the same pigtail when wiring a three way switches. What are the implications of combining a 14/2 and 12/2 ground in the same pigtail?

Stay up to Code with the Latest NEC:


>> 2023 NEC & Related Reference & Exam Prep
2023 NEC & Related Reference & Study Guides

Pass Your Exam the FIRST TIME with the Latest NEC & Exam Prep

>> 2020 NEC & Related Reference & Study Guides
 

Joined: Jan 2004
Posts: 1,507
G
Member
Check out 250.148 for the need to tie all equipment grounding conducors together. And, if the connector used for this tieing together is suitable for mixed sizes, I don't see a problem.

Just as a side note- How does the older issue of the code fit into this issue?

[This message has been edited by George Little (edited 12-06-2005).]


George Little
Joined: Dec 2005
Posts: 64
J
Member
you are supposed to combine them all in the same pigtail. and the tail to the device should be the rating of the circuit to that device.

and the code has had several cycles since your version

Joined: Dec 2005
Posts: 2
D
damoski Offline OP
Junior Member
Thanks very much for your response with regards to combining 14/2 and 12/2 ground in the same box. As for the reason I posted the code (granted it may be old: The ground conductor helps If there's an insulation or short to conduct the electricity away and possibly trip the breaker. In this case, a 14/2 is rated at 15A while a 12/2 is rated at 20A. In case of a short, the 14/2 doesn't seem to have the ca safely for a 20A circuit. May be I am reading too much into this, I need some coffee.

Thanks

Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
Within a reasonable length, #14 will safely trip a 20a breaker with a bolted fault. The theoretical resistance necessary is <6 ohms. That is about 500 feet. Since breakers vary in their trip curves and other things come into play you could probably say 100' is a safer number. Certainly any short jumper would not be a problem. You are still going to bump up against the code tho.


Greg Fretwell
Joined: Aug 2003
Posts: 1,374
R
Moderator
But when do you ever have a bolted fault?


Ryan Jackson,
Salt Lake City
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
If it is an arcing fault, the minor difference in resistance between #12 and #14 is not going to make much difference.


Greg Fretwell
Joined: Feb 2005
Posts: 693
L
Member
Plus, a #14 and a #12 paralleled have a lower combined resistance than either alone, so this only improves performance.


Larry Fine
Fine Electric Co.
fineelectricco.com
Joined: Dec 2002
Posts: 308
E
Member
Does the nec require this. Both 14 and 12 egc to be tied together if they are in the same box.

i have always kept them separate.

Edwrad


Thanks
Edward
Joined: Jun 2004
Posts: 220
T
Member
as george little said above, 250-148 requires that where the circuit conductors are spliced, terminated on equipment within or supported by the box, the grounding conductor with the circuit must be spliced together.


Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5