ECN Forum Forums Photo Discussion Forums Photos for General Discussion What's Wrong With This Picture?

I can't tell who makes that switch but it looks a lot like an Asco. In that case, the source and load lines are going to right places. I couldn't find any info on the neutral assembly, but if that's a switch, isn't the load tied
to the generator position?

OK, here's the deal. Yes the generator feed is not there yet. But if you look at where the grounded conductors land when the generator feed is terminated, the grounded conductor will land on the lug in the middle. The load conductors are landed on the top lugs and the utility feed is landed on the bottom lugs. Even looking up close at the markings on the switch this appears to be correct. Well, it wasn't. The load neutral (grounded conductor) should have been landed on the lug which, in the picture, is empty. This switch feeds an article 700 lighting panel which we used as areas were complete, for lighting during construction. But wait! How did the thing work without the grounded conductor on 277V lighting loads!? That was the $100K question when we found the switch was terminated wrong. ([ side bar.... We found there was a problem when mounting exit lights. The guys were saying they were getting sparks from neutral to the boxes and it was enough potential to register on a tick tracer. We promptly investigated and found this problem /side bar]) We were too pressed for time to investigate then but found out what happened a few weeks later when tracing another problem. There was a bathroom area that remained intact from the original building that we just had to add some down lights to. Well, a janitor closet in that area stayed hot when the circuit feeding it was shut down. Hmmm Well, something is tied together right? But the emergency circuit in the area is C phase and the normal power is A phase. They would have tripped right. Wrong! The original building was phased yellow, orange, brown. All our new stuff was installed a more conventional (and per spec) brown, orange, yellow. The emergency system was new and the normal power panel was an existing feeder. So, yes the circuits were tied together in a box above the restrooms where we tapped into the existing conduit system. (The guy that made it up was gone so we couldn’t even chastise him ) So thinking back to the transfer switch problem this explained why we didn’t see a problem when it was initially energized! The two circuits from different systems being tied together created a path for current to flow back to its source. All emergency power circuits couldn’t go the correct path but it found it’s way from the neutral bus in the panel, back to the box on the other side of the building where the foul up was (via that circuits neutral) back to the main gear via the normal power circuit and feeder! Kind of a comedy of errors don’t ya think? Boy do I love fast track remodels!

n1ist,
You got it!!!

BTW: Its a Kohler switch. They use ASCO internals So it's really an ASCO switch in a Kohler enclosure.

[This message has been edited by Nick (edited 02-26-2004).]

Crash,
An overlapping neutral is a make before break contact. In other words the connection from the normal source is not connected until the emergency source makes contact and visa versa.

Thanks for information Nick. Your picture sparked my curiosity on neutrals in transfer switches. I had been under the impression that all the neutrals were always bussed together in transfer switches.

While, they've got it apart, Nick, they probably should slip some bushings on those connectors...S

On the load conductors running into the top terminals, wouldn't it also have been a good idea to leave a little extra slack in them to allow for any future re-terminations?

And shouldn't the emt connectors have grounding bushing on them, since this over 250volts to ground?

Rick

Scott,
The connectors are insulated throat.

Paul, Yes but it looks so much better this way. (Actually there is slack on the switchgear side of the line feed and there is a pull box just out of site on the load side with a small loop.)

Rick,
Ground bushings not required. All three conduits are in clean KO's.

Boy, Nick
You guys sure get the neatest material.
Colored wire in the larger sizes and everything ...S