oh. apparently i've never read 408.41

Status
Not open for further replies.
brantmacga

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
So, found a link to a mike holt article in another thread and found something interesting referenced in the '02 code. i just found it in the '05 code and it is 408.41 which says:

"Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.

exception: Grounded conductors of circuits with parallel conductors shall be permitted to terminate in a single terminal if the terminal is identified for connection of more than one conductor."

i understand what it means, i just didn't know that i couldn't double-up my neutrals. my question is, in the exception, what are they considering parallel conductors? neutrals off circuits in the same phase? or just the grounding conductor of a 3-wire or 4-wire circuit?
 
no. they are refering to conductors 1/0 and up that are run parallel to create a single conductor for increased amperage.
 
Since parallel conductors are limited to #1/0 and larger they are permitted to be terminated in a lug that is designed for more than one conductor. This wouldn't really apply to a neutral bar in a panel.
 
ok thanks. what about on a back-to-back service, where the panel bonding screw is installed, can i put the grounding and grounded conductors from the same circuit under the same lug?
 
NEC 110.3 B also manufacture states in installation instruction one grounded conductor in terminal bar's terminal holes
 
brantmacga said:
. . . i understand what it means, i just didn't know that i couldn't double-up my neutrals. . .
Click to expand...

It's worse than that, you never could double up the neutrals. The UL 67 standard for class CTL panels has always prohibited this. It just didn't make it into the NEC till the 2002 edition.

- Jim Katen
 
"Double lugging" neutrals is one of those things that catch my eye when I open a panel. . In the area of Ohio that I'm in, I almost never find anyone attempting it. . It's even rare for homeowners to attempt it so the "word must be out", maybe thru the supply house or the friend of a friend that's an electrician.

I do commonly see double and triple lugging of equipment bonding grounds, which is fine.

Double lugging neutrals creates 2 different hazards

1] Multiwire HRs become series 240v circuits if the noodle gets loose or is removed for even an instant while you're removing a different neutral from another circuit. . Resistance in each 120v circuit is almost never equal so when it goes 240v series, the voltage drops are not 120v across loads. . Good way to fry a hidef TV. . Of course the $2 toaster is just fine with it.
I once heard someone say that a hidef TV will always provide overcurrent protection for the dollar store toaster. :grin:

2] When a neutral from a deenergized circuit is purposefully removed, the neutral from an energized circuit can be lost. . That circuit would appear/act like a circuit that was turned off but the hot would still be on and waiting to bite somebody.

David
 
For parallel installations, there is some equipment that is manufactured with lugs designed to take the parallel "Grounded" conductors. Take a 400-amp, TransS CT cabinet for instance. The lugs are designed to take parallel 3/0-CU or 4/0-AL conductors, even in the "Grounded" conductor terminal.



As was stated, this has been in the UL White Book for years and years... I think this goes to show how many people use/don't use the UL White Book. I have been carrying the White Book for years myself, ever since I met Brian McPartland. It is always in my briefcase with the NEC. The 2006 version is the easiest to use by far and has additional information in it as well. Anyone here could get the White Book for free, as a PDF download and a hard copy. Go to the UL website ( www.ul.com) and get to the White Book page for requesting your copy. I believe the current volume comes out every June.
 
Status
Not open for further replies.
Top