Spot the Violations, Part 1001

[480sparky]

Went on a service call today.... school had retractable bleachers in the gym that would not extend electrically. The staff had pulled them out manually enough to gain access to the 'hatch' [the cord you see is for a light underneath]:

Once under the seats, I found a bad contactor in a j-box underneath. The box is fed from a disconnect on the wall (under the seats) with SO cord [top left on this photo below]. More 4-wire SO cord is then run to a control, which energizes the coils of one or the other contactor (for 'in' and 'out'). Two more 3-wire SO cords take power from the contactors to 5 motors.

Here's where the j-box for the contactors is under the seats:

The only way to access this, as well as the disco and the motors, is to extend the seats out all the way and remove a part of the 'floor' of the bleachers. I had to lay on the floor to work in the j-box.


Now the really fun part: Their controller:

A duplex is fed 120v with the black of the cord to one side of the outlet (the 'hot' side). The neutral tab on the duplex is broken, and they plug the switch into either the "In" or the "Out" side of the duplex, depending on which they want to do. The red & white of the SO cord are connected to the contactors (one on each) to run the motors one way or another. The switch just shorts out between the hot & 'neutral' side of the receptacle. To the left of the cut-in box, there is what remains of a sticker, which I would assume to warn someone that this is not a 120v convenience receptacle.

After changing a contactor, I put it all back together, and it all worked.

I did mention to them that something else should be done about their cobbled 'controller' setup. :smile:

 

[brantmacga]

that was a pretty cheap way to do things. we had those fancy electric sliding bleachers installed when i was in school, but they had a start/stop switch mounted on the wall, lockable, by the way.

 

[steve66]

I would hate to be the new teacher who plugs the "controller" into the wrong outlet.

Steve

 

[BryanMD]

that was a pretty cheap way to do things. we had those fancy electric sliding bleachers installed when i was in school, but they had a start/stop switch mounted on the wall, lockable, by the way.

Lockable being the key part.
Sounds like whoever 'engineered' this rig wanted something that the kids wouldn't be getting into as easily as the DT switch that was probably in that j box to begin with.

 

[BryanMD]

I would hate to be the new teacher who plugs the "controller" into the wrong outlet. Steve

I guess all the panels you work with are fully and correctly labeled?

 

[480sparky]

I'm going to start looking at what I can get to replace their 'controller'. I think a keyed switch may not last?

 

[wireguru]

Ive been involved in theatrical lighting for some time, and chain hoists are frequently used. These are wired with a 208v 3ph 4 wire twistlock for power to the motor, and a 480v 3ph 4 wire twistlock for control. the 480v twistlock is used so that control doesnt get accidentally plugged into something else. The 4 wires are used for up, down, common, and ground.

For your application i would do the same thing connector wise, and either use a motor control pendant (handheld deal with up and down momentary buttons and a 4 wire cable handing out of it) or make up a box with a single pole double throw center off momentary switch on it. Definitely use an oddball connector that isnt in use elsewhere in the facility.

 

[Denis]

spotter

spotter

cord subject to physical damage for light

componets not readilly accessible :wink:

I suggest that you use a type L21-20 plug and recep. for the "controller"

momentary switch should be used

are there limit switches?

 

[mdshunk]

That "controller" would also double as a breaker finder. Turn it on, then hunt the one that's tripped.

 

[mdshunk]

I'm going to start looking at what I can get to replace their 'controller'. I think a keyed switch may not last?

An A-B Bulletin 800 keyswitch is bomb proof, but an ordinary key operated light switch (with the slot for that fork key) would probably do the trick.

 

[LawnGuyLandSparky]

Motorized bleachers... isn't this supposed to be phys. ed? We had motorized basketball hoops and divider walls. State law requires all students beyond 1 mile to get a bus for their safety. Then they get to school and slip on some shorts and jog around town for 2 miles...

No wonder the gym teachers were all fat.

 

[grich]

... We had motorized basketball hoops ...

My junior high was in the poor part of town. Hoops moved with a ladder and a hand crank. Between that and running from bullies, I was in pretty good shape.:smile:

Seen both key-operated bleachers, and ones with a plug-in controller (pushbuttons and a twist-lock plug). Whatever it would be, the buttons or key controls were usually momentary for quick stopping in case a rugrat ran in front of the bleachers (I remember one place with mushroom buttons for em-stop).

 

[grich]

480, is that "Fillies" painted on the floor...hard to tell, even if I turn my monitor upside down :grin:

Is that the nearly-new Dallas Center-Grimes gym? (for you non-Iowan readers, the boys teams are nicknamed Mustangs, and the girls mascot is the Fillies) Shame such a new place is already accumulating rigged-up stuff like that...

 

[480sparky]

480, is that "Fillies" painted on the floor...hard to tell, even if I turn my monitor upside down :grin:

Is that the nearly-new Dallas Center-Grimes gym? (for you non-Iowan readers, the boys teams are nicknamed Mustangs, and the girls mascot is the Fillies) Shame such a new place is already accumulating rigged-up stuff like that...

Good eye!

It's the middle school in DC. My guess it was installed back in the Carter administration.

 

[grich]

My guess it was installed back in the Carter administration.

That makes it nearly-new, at least to me:smile: