OT: Panel Isolators

[the_msp]

I normally go for the side of enclosure-mounted isolators. Sure, this means you can open the panel while it's live, however, to do so requires a panel key which your operator should not possess or have access to.

I have been asked for some upcoming panels for front door isolators, interlocked to the contacts on the chassis plate so it can't be opened live. Unless you push the little pin with a pen of course.

My experience with door isolators that are interlocked has generally been poor (17 years in Industry). E.g. they have no unlock pin, so they just get ham-fisted and twisted. Or the bar linking to the contact block drops out as you open the door. This leads to an isolator with no bar, and if say you had an emergency (e.g. fire, not E-stop scenario), you go to isolate the panel and you are turning thin air.

What is your experience and have you any recommendations for a brand that is easy to fit, can be unlocked with a pin to open when the panel is live, and seems to last the test of time?

3 phase 415V <100A

 

[Robb B]

Avoid IEC style components, they are usually cheaper, made of more plastic than the NEMA counterparts, and have a history (for me) of failing exactly as you describe. I have in the past installed a proper disconnecting switch (Siemens, Square D, Eaton, etc) on the exterior of the cabinet (usually on the side wall, which doesn't directly address your problem) and then run the load conductors through a chase nipple or similar to the main contact block. This would also satisfy the "no energized conductors in the cabinet" problem that seems to be more prevalent these days.

 

[jolton]

The best way i have seen to do this is have a key switch on the front to bypass the circuit if you need to open energized. This relies on the key being available when need , we leave our keys in the panel door.

 

[James Mcquade]

we have several enclosures with the following.
an electrical lock on the door which requires a key in order to de-energize the lock so the door can be opened.
james

 

[rupej]

I've had good luck with Eaton / Siemens / Socomec rotary disconnects with interlocking handles. Like these: https://www.socomec.us/range/fuserbloc/

The Allen-Bradley 30A and 60A models are okay too, but 100A and above are terrible.

 

[Puddle]

I've taken to using the ABB OT40F3 isolators. You can buy them as a unit or as separate switch, rod and handle. They're not expensive, they're reasonably solid and they don't droop if they're mounted right.

I use front mounted ones and they have the little pinhole to open because...

a panel key which your operator should not possess or have access to.

The operators will go out and buy their own panel key.

 

[Ronnie Sullivan]

It is a problem that has never been properly assessed by any ruling body.
Even using an interlocked front isolator restricting entrance until the power is turned off still leaves live conductors in the panel.
Isolator should mean just that - it is totally isolated.
A side isolator where the mains is connected and a key system for the door should suffice for the regulations and your culpability.
If an operator or whoever does not turn the isolator off and gets the door open then the onus is on him/her not the panel maker.

 

[Tom Jenkins]

Flange mounted lever operated disconnects with cable connection to the switch and breaker might be what you need.

https://www.zoro.com/square-d-flang...1bk1tut2wvG28gdlxx0zIlyBIHh2yiakaAsknEALw_wcB

 

[DarrylR]

I agree with Tom, lever operator with cable. No bar to fall out as so often happens with those.