Safety reminder

You can get little devices that lock onto breaker handles so that you can lock out breakers that don't have built-in provisions for locks (example). They work reasonably well - someone could probably pry them off, but it would take some effort.
 
I have lockout devices on some of my home breakers that have hardwired appliances without local service disconnects (i.e. oven). I don't know what code is now. I suspect the industrial setting is different anyway.
 
Weldingrod1 said:
Arc flash is metal and/or air being converted to plasma and expanding with great vigor...

Sent from my SM-S911U using Tapatalk
Click to expand...

For illustrative purposes, water to steam is about a 1600:1 expansion ratio. Copper bus bar to plasma is about a 70,000:1 ratio. It acts like a bomb.
We got water into a 13,800V-480V dry three phase transformer a while back, and faulted it out phase to ground, that propagated into phase to phase to phase to ground. The upstream breaker cleared it in about 10 cycles. I had to go take a look inside the enclosure to get "an idea how bad it was" (um, you faulted it, it's junk...). The core weighed 4200 lbs, and i measured the shift in position at about 8". Oh, did i mention one of my guys was on the phone 6 feet away at the time?
 
Ok, so really stupid question here: I've youtube videos of two people in silver fire suits, one with a shepherds hook to pull the other away in case of a disaster, while the first sucker, er. guy actually engaged the circuit. What in the heck is preventing them from building these in such a way that you don't risk your life simply energizing the circuit?
 
They do rate enclosure for energy. However, it may just not be feasible to rate them for cosmic catastrophe. Plus, leaving a tool across the bus bars is NOT according to design!

Having extra protection for the FIRST switch on is just sensible. #2 is much lower risk.

Sent from my SM-S911U using Tapatalk
 
There's also a big difference between load-break and non-load break switchgear.
 
rwm said:
Engineer: I try to make things idiot proof but they keep making better idiots...
Click to expand...
That is my favorite saying, I use it often. "if you try to make it idiot proof you'll only develop a better idiot".
 
You must log in or register to reply here.
Back
Top