120V circuit supplying 2 pole fused disconnect (jumpered on line side)

M

MMayo

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Location
PA
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Electrical Engineer
We have an existing condition in a facility where a single phase, 120V outside branch circuit is serving a 30A 2P fused disconnect. The line side of the disconnect has a conductor jumpered between the two line lugs. There are two circuits coming off the load side.

I am proposing this be corrected, but am struggling to find a code section to cite. Is this a violation or just poor practice? Perhaps it was rationalized as a tap initially?
 
infinity

infinity

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The terminals in the disconnect are almost certainly not listed for two conductors so the jumper is a violation. Remove the conductors, splice on two pigtails and you're good to go.
 
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petersonra

petersonra

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Location
Northern illinois
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engineer
It is not a violation unless the terminals are not listed for two conductors as the previous poster mentioned.

It might not make any sense as to why it was done but it is just one of many design choices.
 
M

MMayo

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Location
PA
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infinity said:
The terminals in the disconnect are almost certainly not listed for two conductors so the jumper is a violation. Remove the conductors, splice on two pigtails and you're good to go.
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Thank you!
 
J

jap

Senior Member
Occupation
Electrician
The whole 2 conductors under one lug was a code rule that was commonly violated for many years.

Even today I have to remind myself not to violate it as I was one of those offenders back then also.

JAP>
 
petersonra

petersonra

Senior Member
Location
Northern illinois
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engineer
jap said:
The whole 2 conductors under one lug was a code rule that was commonly violated for many years.

Even today I have to remind myself not to violate it as I was one of those offenders back then also.

JAP>
Click to expand...
It is only prohibited entirely for grounded conductors, and then only in panel boards iirc Otherwise it depends on the listing.
 
petersonra

petersonra

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Northern illinois
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engineer
jap said:
Most generally lugs aren't rated for 2 conductors.

JAP>
Click to expand...
Depends on the size. Smaller terminals tend to be listed for two. Some I have seen are listed for as many as five.

Most stuff an average electrician would see are probably only listed for one. Especially in larger sizes.
 
J

jap

Senior Member
Occupation
Electrician
petersonra said:
Depends on the size. Smaller terminals tend to be listed for two. Some I have seen are listed for as many as five.

Most stuff an average electrician would see are probably only listed for one. Especially in larger sizes.
Click to expand...

To the contrary, the larger lugs are the ones that will accept 2 conductors, not the smaller ones.

But I wouldn't expect the average engineer to see that very often.

JAP>
 
B

brycenesbitt

Senior Member
Location
United States
petersonra said:
Most stuff an average electrician would see are probably only listed for one. Especially in larger sizes.
Click to expand...
I appreciate SQD's clear diagram for double lugs.
1706158332975.png
Though I realized trying it that it really only feels right if the two wires are the same diameter. I had an upsized wire due to reduced voltage drop, and it was not really happy opposite the regular size wire.

Screws that come down on the wire seem bad for double lugs. But when the screw hits a plate, and doubly so for stranded wire, it's a shame when you can only stick one wire in....
 
infinity

infinity

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brycenesbitt said:
Though I realized trying it that it really only feels right if the two wires are the same diameter. I had an upsized wire due to reduced voltage drop, and it was not really happy opposite the regular size wire.
Click to expand...
What size condcutors are you talking about? The Square D breaker info in your photo would allow two conductors #14-#10. Are you saying that they must be the same size?
 
J

jap

Senior Member
Occupation
Electrician
petersonra said:
The larger lugs often have two holes.
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The larger lugs have (2) holes if they are double barrel lugs, but, most larger "single" lugs are oval shaped and rated for (2) conductors.

The OP is talking about the line side lugs of a small disconnect where you generally find single barrel lugs only rated for (1) conductor.

For that matter most disconnects up to a 200 amp will generally have single lugs rated for a single conductor where you generally find this type of violation where they have used the lug rated for a single conductor to tap off to another disconnect.

No different than the OP's small disconnect where they jumped off of one lug rated for 1 conductor to feed the other.


JAP>
 
J

jap

Senior Member
Occupation
Electrician
You'd also see this violation a lot in contractor fabricated motor control panels where they would tap a smaller conductor from a larger main OCPD to jumper the line side phases to rows of 30 amp 3p fuse blocks.

Most of those single line side lugs on those fuse blocks weren't rated for more than 1 conductor either but there's a ton of them wired that way.

Those that did know about the violation would generally use PDB's to make the transition from the larger conductor to the line side of the fuse blocks.

Oh well,,,

JAP>
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
I was suprised, but many of the single and two hole chair lugs here in the 1/0-250 range can take two conductors per hole:


Single Wire Lugs, 1 Wire Termination per Lug on LugsDirect.com

Buy single wire single barrel terminal lugs. Allows 1500 kcmil to 14 AWG copper or aluminum wire, and are CSA certified and UL listed. Aluminum with tin plating. Made in the USA from domestic and imported parts
lugsdirect.com

Buy Double Wire Cable Lugs, 2 wires per lug at LugsDirect.com

Buy double wire double barrel terminal lugs. Allow 1500 kcmil to 14 AWG copper or aluminum wire, and are CSA certified and UL listed. Aluminum with tin plating. Made in the USA from domestic and imported parts.
lugsdirect.com

As a side note, apparently you can drill and modify the mounting holes, and stack the lugs under one bolt. Oh the horror, the listing violation people are going to have a meltdown!
 
Last edited:
J

jap

Senior Member
Occupation
Electrician
electrofelon said:
I was suprised, but many of the single and two hole chair lugs here in the 1/0-250 range can take two conductors per hole:


Single Wire Lugs, 1 Wire Termination per Lug on LugsDirect.com

Buy single wire single barrel terminal lugs. Allows 1500 kcmil to 14 AWG copper or aluminum wire, and are CSA certified and UL listed. Aluminum with tin plating. Made in the USA from domestic and imported parts
lugsdirect.com

Buy Double Wire Cable Lugs, 2 wires per lug at LugsDirect.com

Buy double wire double barrel terminal lugs. Allow 1500 kcmil to 14 AWG copper or aluminum wire, and are CSA certified and UL listed. Aluminum with tin plating. Made in the USA from domestic and imported parts.
lugsdirect.com

As a side note, apparently you can drill and modify the mounting holes, and stack the lugs under one bolt. Oh the horror, the listing violation people are going to have a meltdown!
Click to expand...

Yes, when you buy a single lug, but, the lugs that come in the factory diconnects are generally not your standard after maket chair or stack lugs.

JAP>
 
J

jap

Senior Member
Occupation
Electrician
Just looking at Eatons Disconnect lug capacity specs for instance V2-T1-16.

The 400 amp is the only one with a note 3 beside it that indicates "Note 3" Single barrel lug that accepts one or two cable per phase".

All the rest do not.

JAP>
 
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