Wires crossing in a 3 phase disconnect

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TheElevatorGuy

TheElevatorGuy

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New York, New York
Hello all,
I would like to know if it is code compliant to physically cross wires from the Line side of the disconnect switch and the Load side of the disconnect switch. I am involved in elevator applications and I have always seen it done where these wires never cross within the 3-phase disconnect switch. The line side would be on one side of the switch and the load side would use the other. If the code section can be referenced if this is true please mention it and thank you for your effort on my behalf.
 
There is no NEC section that prohibits crossing the conductors as you've described. I have heard over the years that it not permitted by the NEC but that is an electrical myth.

Welcome to the Forum. :)
 
Not sure if you mean rotation or transposition or for some really strange reason wiring one leg up backwards.

There is good reason on 1 or 2 pole equipment. In a contactor you want to wear out the poles as evenly as possible. In a one or two phase situation the extra poles are often wired series to maintain the same current on all three poles so there is an extra diagonal wire or two. For example in a wound rotor motor the resistor banks only require 2 pole contactors to make a star/wye connection. The extra pole is in series with one of the used poles. The same logic holds but wear in a disconnect is so low there is no reason to do it.
 
paulengr said:
Not sure if you mean rotation or transposition or for some really strange reason wiring one leg up backwards.

There is good reason on 1 or 2 pole equipment. In a contactor you want to wear out the poles as evenly as possible. In a one or two phase situation the extra poles are often wired series to maintain the same current on all three poles so there is an extra diagonal wire or two. For example in a wound rotor motor the resistor banks only require 2 pole contactors to make a star/wye connection. The extra pole is in series with one of the used poles. The same logic holds but wear in a disconnect is so low there is no reason to do it.
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Kind of my question as well, what exactly is meant by "crossing".

Having line and load conductors pass near each other within the enclosure is fine, any other meaning of "crossing" needs more detail before we can answer.
 
Reading the OP carefully, it sounds like they're talking about the line conductors entering the bottom of a disconnect and running up the side to the line terminals, also the load conductors enter at the top and running down the side to the load terminals. I see nothing wrong with that.

This is the kind of thing where a pic or sketch would be clearer than the words.
 
When I worked at a steel mill, what you described, line on one side, load on the other and no crossing of them, was an installation standard enforced by the mill itself, just a workmanship issue really. That sort of thing is not uncommon, but it's not something the NEC is concerned with.
 
I was confused by saying "switched before". The way I see the disconnects, the line goes in the top side and load at the bottom. With the line at the top, when the knife switch is open, the fuse holders are disconnected from power. Is that correct?
 
Little Bill said:
I was confused by saying "switched before". The way I see the disconnects, the line goes in the top side and load at the bottom. With the line at the top, when the knife switch is open, the fuse holders are disconnected from power. Is that correct?
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Yeppers. (y)
 
The timing of this thread is so strange. Just TODAY I was working with a fellow electrician to help him on a job moving a 3Ø service.
We had to put in a 3Ø disconnect since the panel was staying where it was but the meter was being moved. We did this a little different than normal. The disconnect had a place for a hub so we used this for the load feed. We put the meter right beside the disco, with the meter also being an overhead service. I was wiring the load wires that were coming in from the top. I had to bring the conductors down the side and back up to the load side lugs. My friend asked me what I was doing that for. He said "why don't you just land them on top where they were coming in?" I had to explain to him that the line side from the meter went there because the fuses/holders had to be disconnected from power to change a fuse. He had never worked on anything like a fused disco.
 
Little Bill said:
He had never worked on anything like a fused disco.
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This shows why any active electrician is always learning something new. I still am, and hope that never changes (or at least until I know everything. ;) (cue the Farmer's Insurance jingle))
 
LarryFine said:
This shows why any active electrician is always learning something new. I still am, and hope that never changes (or at least until I know everything. ;) (cue the Farmer's Insurance jingle))
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True, and I in no way meant that I know everything or even more than my friend. He is a "MacGuyver" at finding paths to run wire and figuring out how to get it there.
 
LarryFine said:
This shows why any active electrician is always learning something new. I still am, and hope that never changes (or at least until I know everything. ;) (cue the Farmer's Insurance jingle))
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I find that idiots are the hidden geniuses. If there is a truly creative way to do something stupid they will find it.
 
Jraef said:
When I worked at a steel mill, what you described, line on one side, load on the other and no crossing of them, was an installation standard enforced by the mill itself, just a workmanship issue really. That sort of thing is not uncommon, but it's not something the NEC is concerned with.
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A lot of these job specs are based on an incident in years past, safety or equipment damage. Where I worked I did detail drawings so installations would be consistent. But 10 electricians will wire the same job 10 different ways, all to code.
 
Little Bill said:
He is a "MacGuyver" at finding paths to run wire and figuring out how to get it there.
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I am, too. I once ran a generator feeder cable from outside a large house to an interior utility room in the center of the basement, meaning it had no exterior walls, and every pathway would have to be through a finished room. I was told they had other electricians tell him it couldn't be done without patching.

I found a pathway that went from the outside, through a band joist and across the extra-high ceiling of a downstairs recreation room, halfway down the opposite wall, and inward through a narrow unfinished chase to the utility room, and I didn't have to make a single access hole that required patching.

I investigated and noticed that there was a pair of ceiling speakers in line that also happened to align with a wall sconce on the wall opposite the exterior wall. I also measured around a few walls and doorways, and found the 1-foot wide "panhandle" of a chase that happened to dead-end behind the sconce.

So, after winning the job, I removed the ceiling speakers and the wall sconce and its box. I used the speaker holes as hand access, fed the cable around the bend and down the wall where there was miraculously no top plate, and through a hole I bored through the cinder-block wall and into the chase to the ATS.
 
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