Disconnect

Greg Dake · Mar 25, 2010

Greetings,

I'm designing a 3-phase VFD enclosure. The enclosure doesn't have a flange. Are one of these, externally mounted, acceptable for use as a disconnect means for the entire panel?

TIA,

Greg

http://www.hubbellcatalog.com/wiring/catalogpages/page_C20.pdf

WireGuy1950 · Mar 25, 2010

You could just use a through the door disconnect, non-fused,fused or circuit breaker like the ones from Bussmnan, AB or ABB

Greg Dake · Mar 25, 2010

Thanks for the reply, I'm actually trying to stay away from the "through the door" syle on this particular project.

Greg

jstolaruk · Mar 25, 2010

Not if you need the door mechanically interlocked. I'd use WireGuy1950's recommendation assuming you don't have a huge power requirement; the bigger versions (>100A) get pretty pricey.

Greg Dake · Mar 25, 2010

The disconnect size will be 100A.....I'll go with electronic door interlock....

Greg

The Plc Kid · Mar 25, 2010

I agree thru door sux. When they get a little age/wear in the they don't want to line up correctly and are a real PITA

leitmotif · Mar 25, 2010

The Plc Kid said:
I agree thru door sux. When they get a little age/wear in the they don't want to line up correctly and are a real PITA

Observations on thru door disconnects.
1. As PLC Kid said they wear and then do not line up well
2. I always found it interesting seeing lockout tag hanging on door operator with door wide open and the breaker inside shut. Have done myself when got all wrapped up troubleshooting.
3. You still have the incoming line hot.

I much prefer an entirely separate disonnect.

Dan Bentler

JeffKiper · Mar 25, 2010

You might look at a sidewall mount disconnect.

monkeyhead · Mar 25, 2010

leitmotif said:
Observations on thru door disconnects.
1. As PLC Kid said they wear and then do not line up well
2. I always found it interesting seeing lockout tag hanging on door operator with door wide open and the breaker inside shut. Have done myself when got all wrapped up troubleshooting.
3. You still have the incoming line hot.

I much prefer an entirely separate disonnect.

Dan Bentler

I prefer a side slung disconnect separate of the enclosure for precisely this reason. Otherwise by our safety rules, I have to lock out the source breaker.

bguinn · Mar 25, 2010

I use cable type disconnects usually from SQ D but ABB and Cutler Hammer also have them. Automation direct sells the cutler hammers. They have metal handles just like a disconnect handle so LOTO is not a problem. You also don't have to worry about alignment problems with it being a cable/flexible operator. All you really have to be concerned with is the panel depth.

TimWilborne · Mar 25, 2010

If you strictly follow NFPA79 don't you pretty much have to have a completely external disconnect now?

Disconnect

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