Square D 100A DISC Wire Terminations

[Nardie]

I have a Square D fusible disconnect switch H363 which accepts conductors from #14 AWG - #1/0 AWG copper. I want to install a #10 AWG and #6 AWG conductor under each phase lug. I am taping each conductor from the 100A disconnect to feed different loads. The Square D datasheet list that the H363 disconnect switch accommodates one conductor per phase, and Square D doesn't offer a double-lug kit for this disconnect switch. Since the conductor range is up to a #1/0 AWG, I don't see a problem double tapping from the load side with the proposed conductor size. Am I missing something or am I okay, so folks disagree with this concept based on the datasheet information. Thanks

 

[Jraef]

What you are missing is that you cannot use a device in a manner in which it is not listed to be used. The lugs are listed for only one conductor. End of story. Article 110.3.

What you CAN do is to install a tap device like a Polaris block in the box that gives you multiple terminations. You must pay close attention to wire bending space, but that’s usually not too difficult.

 

[Little Bill]

If you try and put a #6 and a #10 in the same lug, the clamp/plate will contact the #6 first and won't be able to tighten enough to clamp the #10.
You could do similar to what Jraef said and use a Polaris tap with three holes. Two in and one pigtail out to the lug. But doing that, how would you fuse that to protect the #10 wire?

 

[Cow]

Install a j-box/gutter/etc adjacent to the disconnect. Run full sized 100 amp wire from the disco to the j-box/gutter/etc and tap the #6's and 10's to that.

 

[infinity]

You can twist a #10 and a #6 together and install a wirenut to make a connection that will last 100 years but you cannot twist together a #10 and a #6 and install it in a terminal. That connection might only last 90 years. :roll:

 

[kwired]

If you try and put a #6 and a #10 in the same lug, the clamp/plate will contact the #6 first and won't be able to tighten enough to clamp the #10.
You could do similar to what Jraef said and use a Polaris tap with three holes. Two in and one pigtail out to the lug. But doing that, how would you fuse that to protect the #10 wire?

His conductors are possibly feeder taps and land at appropriate overcurrent device?

You don't want to know how many old grain bin installs I have seen over the years with a 200 amp fused disconnect for service disconnect and many feeder taps jammed into the load side lugs to supply additional branch circuit disconnects.

 

[electrofelon]

You can twist a #10 and a #6 together and install a wirenut to make a connection that will last 100 years but you cannot twist together a #10 and a #6 and install it in a terminal. That connection might only last 90 years. :roll:

I agree, I kinda think that generally prohibition again "double tapping" is ridiculous. As you say we can use wire nuts, and we can custom twist up the outer conductor of SEU cable..... Some lugs do take two conductors squashed together (usually have to be same size) and I dont see what is so special about those. Ive never really been impressed with mechanical lugs anyway: sometimes strands get pushed out and and up floating in air and/or enequal pressure on different parts of the conductor. I dont think they are really highly engineered things by any means where a combination of two conductors will make them not work. I think a pressure plate in front of the set screw would be much better. I see those sometimes on older equipment but never seen one modern. Anyway, but of course code is code......

OP, sometimes you can replace the lugs with double ones if there is physically enough space, although often there isnt on smaller equipment.

 

[infinity]

I agree, I kinda think that generally prohibition again "double tapping" is ridiculous. As you say we can use wire nuts, and we can custom twist up the outer conductor of SEU cable..... Some lugs do take two conductors squashed together (usually have to be same size) and I dont see what is so special about those. Ive never really been impressed with mechanical lugs anyway: sometimes strands get pushed out and and up floating in air and/or enequal pressure on different parts of the conductor. I dont think they are really highly engineered things by any means where a combination of two conductors will make them not work. I think a pressure plate in front of the set screw would be much better. I see those sometimes on older equipment but never seen one modern. Anyway, but of course code is code......

OP, sometimes you can replace the lugs with double ones if there is physically enough space, although often there isnt on smaller equipment.

Yes, I use the SE cable analogy quite often when this comes up and I've seen some horrible twist jobs on the aluminum neutrals in panels. But as you've stated code is code, it would be hard to test every possible combination in a terminal but depending on how the conductors are installed it's possible that the conductors from the OP could be made electrically sound in a single lug.

 

[kwired]

I agree, I kinda think that generally prohibition again "double tapping" is ridiculous. As you say we can use wire nuts, and we can custom twist up the outer conductor of SEU cable..... Some lugs do take two conductors squashed together (usually have to be same size) and I dont see what is so special about those. Ive never really been impressed with mechanical lugs anyway: sometimes strands get pushed out and and up floating in air and/or enequal pressure on different parts of the conductor. I dont think they are really highly engineered things by any means where a combination of two conductors will make them not work. I think a pressure plate in front of the set screw would be much better. I see those sometimes on older equipment but never seen one modern. Anyway, but of course code is code......

OP, sometimes you can replace the lugs with double ones if there is physically enough space, although often there isnt on smaller equipment.

I think the problem is with listing or the non desire of manufacturers to get them listed for such combinations. Reality I think is that some combinations are probably just fine, they just never been tested to assure they are fine.