One of the projects we are working on there is a room with exposed motor starters on the walls. We have decided to label the door to the room. These starters run about 3 feet apart there are two substations feeding these starters. I have 3 questions:

1. Could an arc flash on one starter encompass and initiate an arc on another starter?

2. If so, would the incident energy be additive?

3. How would you account for this in the calculation?

It is unlikely that an arc flash event on a LOW VOLTAGE system would cause another arc flash event on an adjacent system 3 feet away, unless molten metal/ plasma was projected in that direction. A medium voltage arc might jump to adjacent systems 3 feet away, but it is unlikely there would be different systems unguarded so close together. I would expect that Arc Flash energy could be added, but the question is suspicious.

Need more informaiton, low voltage, medium voltage, kva of source all would be good starts.

It is possible to have the plasma cloud from a meltdown move to adjacent equipment but the bigger danger is it moving up the supply line conductors and that would be bad.

What happened to the requirement that exposed equipment be guarded? Does the room have a fence seperating the starters from the rest of the room. Would the arc flash boundry extend beyond the fence.

it's probably an old plant i have seen this once
no low voltage was enclosed
you had to be carefull is was running a 3000hp 600Vdc motor and large spark were seen when the motor was changing direction every 5 second or so