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mamills #166007 07/09/07 11:12 PM
Joined: Nov 2001
Posts: 52
KJ Offline
Junior Member
call me an idiot, but whats just losing my mind, so help me find

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KJ #166016 07/10/07 08:25 AM
Joined: Nov 2001
Posts: 745
Hi KJ: I always thought it meant an EXternally Operable switch, aka a Safety Switch. Someone please correct me if I'm mistaken.

Mike (mamills)

mamills #166020 07/10/07 01:03 PM
Joined: May 2005
Posts: 167
I've seen those called EPOs, Emergency Power Off

brianl703 #166040 07/11/07 12:47 AM
Joined: Nov 2001
Posts: 52
KJ Offline
Junior Member
told ya i was losin it.....
amazing what many years of brain cell destruction has done.....

Admin #166215 07/16/07 02:19 AM
Joined: Jun 2007
Posts: 50
Aren't most electrical products rated to operate at 40-50*C ambient temp anyway? It's not like this fuse box is a PC or other sensitive electronic device.

If they are interrupting load, they are overloaded.... 'nuff said! Nice taps too.... BOOM!

Some people know just enough to be dangerous. The excuse sounds like something only an engineer could come up with. Seriously, I know some EE majors in class and they don't know JACK about being safe. I think I'm the only one in class besides the prof that knows what NEC stands for. LOL!

HotLine1 #166223 07/16/07 05:42 AM
Joined: Aug 2001
Posts: 7,520
Originally Posted by HotLine1
As to the bare buss, that's how it was

This reminds me of a subject which came up on the (British) I.E.E. forum a short while ago.

Modern distribution panels here tend to have the terminals and busbars covered up to a much greater degree than present-day American equipment. Older panels were much more exposed though. Somebody was suggesting that an old Crabtree C50 breaker panel (typical 1970s commercial) should warrant at least a "code 2" on an inspection (meaning requires improvement) due to the exposed busbars inside. Somebody else was absolutely insistent that it should be "code 1," meaning immediate attention required, and that it should be replaced as a matter of urgency.

The fact is, so long as all the energized terminals and busbars are enclosed when the cover is in place those older panels are still perfectly in accordance with regulations today.

pauluk #166227 07/16/07 08:19 AM
Joined: Mar 2002
Posts: 360
Quick jump in,

My Trains have a 240v three phase supply that runs the length of the train. It is protected by a 50 amp three pole breaker at the car with the generator. It lives in a raintite box under the car.

In the summer, when ambient approaches 90, and the sun is beating on the box that the car knockers have painted black, the breaker trips cause it dang well feels like it. Because of where it lives and it's 90 degree trip, ambient air temp trips it, rather than overcurrent. I am not far from putting equipment fans in the box to cool it off. With maybe a duct to pull the air over the ice box first.


never underestimate the perversity of an inanimate object.

hardwareguy #166240 07/16/07 02:20 PM
Joined: Nov 2002
Posts: 794
Likes: 3
Originally Posted by hardwareguy

Some people know just enough to be dangerous. The excuse sounds like something only an engineer could come up with. Seriously, I know some EE majors in class and they don't know JACK about being safe. I think I'm the only one in class besides the prof that knows what NEC stands for. LOL!

I'm an EE major (I've since graduated as a BSEE). Realize that we get taught mathematical and physics theory. And the idea that something that once functioned can fail is rarely ever mentioned. And thus designing things to fail in a safe condition isn't mentioned. Most of the things EEs would ever work on are inside chips, and the currents are in microamps, and voltage rarely above 5V. Thus the problem you can get when a EE engineer starts to mess with house wiring, if he doesn't really comprehend what the equipment grounding conductor is really for. I knew someone who bought an older house that had two wire romex without the ground, and he replaced the outlets with 3 prongers. He just strapped the neutral to the ground, figuring that would be okay as both are at zero volts. "What if that neutral goes open, then the computer will end up riding on 120VAC on its case?". Something he hadn't thought of.

And of course "NEC" is the name of a Japanese comsumer products company.. laugh

wa2ise #166250 07/16/07 04:30 PM
Joined: Jan 2005
Posts: 5,422
Likes: 1
Cat Servant
Hardwareguy, I have seen this situation, where the ambient was high enough to matter. For example, where the panel supplied an oven's heating elements. It's rather annoying to watch 30 amps of current blow a 50 amp fuse! It's usually in such a location where I find such open panels.

Some guys get fancier, and mount little fans to the side of the enclosure. I have even seen outdoor switchgear with roof 'turbine' fans mounted on them. While this is considered a listing violation, it is an attempt to reduce the temperature inside the cabinet to something reasonable.

Wa2Wise, thx for the explanation of an EE's education. On my jobs, the engineer and I have an understanding ... he stays clear of the electric work, and I stay away from the bridge design laugh

Trumpy #166268 07/16/07 11:14 PM
Joined: May 2001
Posts: 377
I have had Inspection allow supplemental cooling but im in Canada so...We were told to contact the whosalers\manufacturers to find the solution then call inspection back for special permission.They also mentioned that up to 33% in increase o\l capacity could be achived.I have also heard they run compressed air though the MCC's in the Windsor saltmines.If no kits or other viable oppions exist the inspectors wont sign off on it and a work order is issued to replace it.They cant modify performance of equipment without approval or insurance can and will drop them.They have no insurance if that hurts somone.

Last edited by frank; 07/16/07 11:24 PM.
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