Is it "legal" to stagger (3) single phase fuses of a 3-phase ckt in a control panel ?

[bdn2004]

We are trying to install some new 400A fuse blocks and fuses into an existing industrial control panel. A 3-phase fuse block is too wide to fit in the available space in the panel. Single phase fuse blocks would work if they are staggered as shown. Is there any reason or Code that prevents doing it like this?

 

[waross]

I can't think of any code restriction.
It will be considered poor practice by many electrical persons.
Two thoughts:
1.Sometimes you gotta do what you gotta do.
2.Try harder.
(Look for different hardware that will fit in the panel. Consider a different type of fuse if possible.)

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[che12345]

Dear Mr bdn2004
Have you considered
a) placing three fuse-blocks [horizontally] which is acceptable by the Code , instead of [vertically] ?,
b) replace the 3 fuses by a single [3-pole MCCB]? BTW MCCB may be placed horizontally or vertically without any restriction. Another advantage is that MCCB would prevent " single-phasing " for good.
Che Kuan Yau (Singapore)

 

[bdn2004]

che12345,

Yes I have considered the horizontal fuses and many other things including the circuit breakers. At this point it's: here's the issue, now let's find the easiest way to do it.

The horizontal mounting might work in another open place in panel...but like said this is 400 amp fuse blocks. And parallel #1/0 wires. They are not small or easy just to bend around in that cabinet.

It seems the easiest way to do it is to mount another box or a fused disconnect switch to the back of this box and nipple through back and forth.

In my spare time I like remodel houses with this retired Contractor. He said to me once: "Remodeling stuff you gotta be very creative and you need every tool in the shed. I could build a new house with 4 tools". Same thing.

 

[mparenteau]

Phase to phase clearance issues (top to bottom fuse clips)? May need to install some type of glastic barrier between the upper and lower section.

Mike

 

[jraef]

Phase to phase clearance issues (top to bottom fuse clips)? May need to install some type of glastic barrier between the upper and lower section.

That's the biggest issue I see as well. In a pre-assembled 3 pole fuse holder, all of the proper Line to Line air and surface clearances are factored into the design of the nit. When you do it with single pole devices, YOU become responsible for all of that and an inspector may or may not like it without additional barriers. They might still reject it based on "suitable for the intended use" issues.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[che12345]

Dear Mr bdn2004
Please remember that ALL 3-phases+Neutral+Earth conductors are bundled together and go through only ONE opening between the existing Board to the new fuse-block box; at the back. Do NOT make several holes with one conductor in each hole; for easy installation. At 400A [eddy current effect] shall be taken into consideration, if the board and the box are of metallic/ferrous material.
If for practical reasons, serval holes are needed; use non-ferrous gland plates or cutting a slot in between the holes or with split gland plates with a small gap in between. The intention is to prevent [eddy current] heating effect.
Che Kuan Yau (Singapore)

 

[wbd]

Is this existing industrial control panel UL listed? If so and UL listing is required, you may be invalidating that UL listing.