Calling Steve Terry.... Why aren't
dimmer racks treated by the
NEC like motors,
HVAC units, and other permanently connected equipment,
where a disconnect switch is required to be within sight of the unit? It seems to me that his should be written into the code, if it isn't already. A simple, non-fusible,
switch is all it would take.
They call them "safety switches" for a reason.
@FMEng Writing in support. A
PAC constructed from the foundations up in downtown Burlington, Ontario opening in 2011 had two
dimmer rack rooms, one for each
theatre. The larger
theatre's room housed four 48 slot / 96
dimmer racks but there was only sufficient wall space to accommodate three 400 Amp three
phase isolation switches. The electrical consulting PENG was choosing to locate the fourth isolation
switch in a busy secondary substation room at
stage level two floors below. My immediate boss / employer was the A/V subcontractor and sternly advised me that this was none of my business and to keep out of it. I had show
monitor video, audio and intercom locations in the room. I kept looking at the room and wondering why the architect had chosen to make the room with one corner chopped off at a jaunty angle rather than leaving the
dimmer room rectangular like our audio rack room one floor directly below. I'm not good at watching dumb go by without a good reason. One day when the the electrical PEng was on site and had a free moment, I asked him if he'd have a problem with putting all four 400 Amp three pole isolation switches in the room with their racks. He had no problems and mentioned it would be his preference if the room was rectangular gaining sufficient wall space. Next time the architect was cruising through and had a moment, I asked him why my A/V rack room on the second floor was rectangular while the
dimmer room directly above on the third floor had one side chopped in at a jaunty angle. Basically there was no good reason and no conscious thought behind the irregular shape of the room. As the
block layers had yet to
build up the walls in this area of the third floor and it was all just spray paint on the concrete slab, all it took to sort this was to put the right people in touch with each other and the yet to be built room was built rectangular, the bricky's were pleased to be building a standard 90 degree corner rather than two bizarre angles, the electrical PEng was pleased to locate all four of his 400 Amp isolation switches in the
dimmer room immediately across from their four respective racks and the end users were delighted not to have to find their way to one of their isolation switches in the middle of the building's busy secondary electrical sub two floors below at
stage level. Sometimes you can win if you
point out a concern early enough, chat up all the right people at the right times and
thrust them into communicating with one another.
This nosy old
blind geezer crawls back into his hole.
Toodleoo!
Ron Hebbard.