Found an old code book that says we used to run 3/0 feeders for a single elevator

I was cleaning out my dad's garage and found his 1972 NEC code book. It was open to the elevator section. The spec for a standard hydraulic unit called for a 3/0 copper feeder. I checked it twice. That's massive for a single car by today's standards. Makes you think about how much the gear has changed. Anyone else come across old specs that seem totally wild now?

3 comments

3 Comments

diana_west272d ago

Honestly that old spec doesn't surprise me at all. We had to replace a feeder for a 70s elevator a few years back. The old motor starter was basically a brute force device, it just slammed the motor online. You really did need that giant wire just to handle the heat from the startup. Tbh the best move is to check the actual motor nameplate and controller before you touch anything. A modern retrofit with a soft starter can usually let you drop down a couple wire sizes, which saves a ton on copper costs.

the_tessa2d ago

My grandpa's shop had a 1970s elevator with 4/0 aluminum feeders. We traced it back to the old motor controllers having huge inrush currents, like 600% for several seconds. Modern VFDs are way softer on startup.

xenaf512d ago

That huge inrush current thing makes sense, it's like old appliances that dimmed the whole house when you turned them on.