A while back, I wrote an article for Doors & Hardware about panic hardware requirements for rooms housing electrical equipment. The rule of thumb is panic hardware is required if the room has equipment with more than 600 volts, or more than 800 amps (previously 1200 amps), or if it’s a battery room. This is based on the 2014 National Electrical Code – the International Building Code has slightly different requirements but we’re working on making the two consistent in the next editions.
Someone asked me recently how the voltage and amperage are determined. Do you add up the voltage or amperage of each piece of equipment and look at the total? Or is it the highest voltage/amperage of any piece of equipment that determines whether the room is over the threshold where panic hardware is required?
To be honest, I had never thought about this question specifically. I guess I assumed that it would be handled in a similar way as sizing a power supply – all of the loads are the same voltage, and you add the amperage of each load to find the total amperage. I was thinking about electrical rooms the same way…if someone had put me on the spot I would have looked at the maximum voltage to see if it was over 600 volts, and added the amperage of each panel to see if the total was over 800 amps.
I couldn’t find the answer in NFPA 70 – The National Electrical Code, so I asked NFPA and was told that you consider the piece of equipment with the maximum voltage and the piece of equipment with the maximum amperage. For example, a room with one piece of equipment rated at 800 volts would require panic hardware, but a room with 2 pieces of equipment rated at 480 volts each would not. A room with one piece of equipment rated at 1000 amps would require panic hardware, but a room with five 200-amp panels would not.