Through-Door Racking

[big john]

I've been hearing a lot lately about through-door breaker racking being a "safe" alternative for racking circuit-breakers without de-energizing or wearing or flash suits. The advertisements for metal-clad gear with this feature will show some guy doing the racking through a hole in the closed doors, wearing minimal PPE (maybe HRC 0 or 1).

How safe is this?

Metal-clad gear is pretty heavy-duty, but I wonder about the ability of the gear to withstand a line-side fault without seriously injuring the personnel on the outside. I ask because this is starting to get close to home: We have MV utility-tie breakers that cannot be de-energized without knocking out substations. The safety procedure being suggested is to do closed-door racking while wearing a 40 cal suite. Seeing as how I'm the guy who'd be doing the racking, I'm not too sure how comfortable I am with this....

Is it just a matter of getting the SCCR of the gear and determining the available fault current to see if we're in the danger zone?

-John

 

[Pierre C Belarge]

The only safe proceedure for racking circuit breakers is to let the apprentice do it.
Only kidding.

I here about so many incidents in regards to breaker racking. The only way I know that is relatively safe is the remote racking.

 

[zog]

I've been hearing a lot lately about through-door breaker racking being a "safe" alternative for racking circuit-breakers without de-energizing or wearing or flash suits. The advertisements for metal-clad gear with this feature will show some guy doing the racking through a hole in the closed doors, wearing minimal PPE (maybe HRC 0 or 1).

How safe is this?

Metal-clad gear is pretty heavy-duty, but I wonder about the ability of the gear to withstand a line-side fault without seriously injuring the personnel on the outside. I ask because this is starting to get close to home: We have MV utility-tie breakers that cannot be de-energized without knocking out substations. The safety procedure being suggested is to do closed-door racking while wearing a 40 cal suite. Seeing as how I'm the guy who'd be doing the racking, I'm not too sure how comfortable I am with this....

Is it just a matter of getting the SCCR of the gear and determining the available fault current to see if we're in the danger zone?

-John

The SCCR rating and the fault current available are important for application of the gear ans the ability of your breakers to interupt faults downstream but has little to do with arc flash protection. Your acr flash analysis assumes thee ratings are correct. But unless you have arc rated switchgear the encosures were not designed to contain an arc flash and you still need to wear the PPE rated for the hazard level, in some case even a 40 cal suit wont protect you.

You need to eaither mitigate the fault or use remote racking. This is what my job is, mitigation solutions on switchgear. If you provide more info about your systems I may be able to provide a solution. Remote racking is very popular, my company has a solution for any equipment you have, nearly every utiliity in North America is using our system.