Electrical Tip Of The Day

Lord.

AND NOW, an annoying story from the old days

When I first got into HVAC, we got a call on a rooftop unit in downtown Spokane, "old OLD building." We had to remove the blower. But there is a PROBLEM

Many? most? rooftop units have a dedicated entry for the AC power, usually down low on the cabinet. For whatever reason --this one was installed long before codes got stiff or enforced-- the installer had come up through the roof with conduit, run it neatly right into the unit, BUT WAIT!!! there is no DISCONNECT!!

So they had mounted a nice big 3 pole (this was 3 phase) disconnect right on top of the cabinet RIGHT on top of the blower compartment, then run the three incoming hot wires from the entrance, up through the blower compartment to the disconnect, through the disconnect, and then run the three power feeds to the unit back down through the blower compartment--to tie in to the power entrance below it.

So when you remove the blower access panel you have SIX conductors running vertically from top to bottom RIGHT IN FRONT OF THE BLOWER. (sort of like a jail cell LOLOL)

So you pull the disconnect, you STILL have three wires that are HOT

Well, we go down below, we looked and looked, and asked anyone we found, and COUND NOT find whatever breaker/ fuse fed that circuit

Finally, we pulled the six "cold wires out of the way, then CAREFULLY, standing on a wood box, with plywood leaned up against the unit for insulation, ---one at a time, removed the "hot" wires and taped them off, then pulled them out of the way.........

Replaced the motor, serviced the unit, and put all the wires back.

At the time I even briefly came up with the bright idea, "let's throw a wrench across the switch, turn it on, and see what breaker trips"

IT TURNED OUT A FEW YEARS LATER that building suffered a little fire. And that AC circuit was a completely illegal "tap" in a wire tray off some huge feeders. Those little bitty no 8 conductors would have lit up like light bulbs!!!