Turn off dimmers or not?

[StradivariusBone]

I was just informed that over our holiday break, the electric utility will be repairing our building transformer outside (which is slowly sinking into the ground at an angle for some reason). I won't be here for about 2.5 weeks and am concerned that they might be cycling the power on and off to test things and I'm wondering if I should turn off the switch to our dimmer rack. It's an ETC Sensor with 196 dimmers. It's never off unless the power goes out.

 

[sk8rsdad]

I wouldn't lose sleep over it. The only thing at risk is the CEM and that risk is negligible. They probably won't be cycling power more than once, or maybe twice, when they disconnect to do the work then reconnect when the work is done.

 

[JD]

For the sake of sleep, I would kill the power. Blackouts happen all the time so it is no different and I doubt harm will come. Still, they are going to be killing power to what is probably a 13kv transformer, disconnecting it, repairing the slab, re-installing the transformer, and connecting it back up. Accidents do happen, but the kind I am thinking of would make the dimmer problems a minor issue by comparison!

 

[DavidNorth]

For the sake of sleep, I would kill the power. Blackouts happen all the time so it is no different and I doubt harm will come. Still, they are going to be killing power to what is probably a 13kv transformer, disconnecting it, repairing the slab, re-installing the transformer, and connecting it back up. Accidents do happen, but the kind I am thinking of would make the dimmer problems a minor issue by comparison!

Absolutely agree. While likely no issues will occur, no sense tempting Fate. We've seen phases cross connected and phase-neutral swaps, only some of which could cause issues, but get some rest and turn off the feed breaker. In fact, turn off everything that you do not absolutely need running.

David

 

[TheaterEd]

Absolutely agree. While likely no issues will occur, no sense tempting Fate. We've seen phases cross connected and phase-neutral swaps, only some of which could cause issues, but get some rest and turn off the feed breaker. In fact, turn off everything that you do not absolutely need running.

Just make sure to leave several notes so custodial doesn't freak out.

 

[StradivariusBone]

Just make sure to leave several notes so custodial doesn't freak out.

We do have high-bays we use as ghost lights that are fed separately, but the custodial staff should be on break too.

Thanks for the advice all! I think we'll err on the side of caution and not give anything for the gremlins to fiddle with over the holidays.

 

[FMEng]

Following the power company's work, check the direction of rotation on your three phase motors. HVAC blowers would be an example. The line crews try hard, but it's real easy for them to swap a couple of phases at the transformer and cause things to run backwards. I've seen it happen a few times.

 

[gafftapegreenia]

According to legend at my alma matter, the old Electro Controls rack was killed when WE Energies cut power to the theatre by accident mid show. Mind you, I don't know what got fried or how bad, but they got a Sensor rack out of it, so I didn't press the issue.

So for the sake of sleeping at night, sure, shut it off.


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[tjrobb]

Normally there is an ordered shutdown and startup. Down by going small to large and up by large to big loads. This reduces the surge current and the chances of nuisance breaker trips. I'm a little surprised there are no plans for this; surge / sudden magnetic increase can nuke a transformer.

 

[SteveB]

Normally there is an ordered shutdown and startup. Down by going small to large and up by large to big loads. This reduces the surge current and the chances of nuisance breaker trips. I'm a little surprised there are no plans for this; surge / sudden magnetic increase can nuke a transformer.

When they upgraded our service feeders a few years back, they had us shed all loads prior. I shut down everything - racks, electronics, console, etc... Doesn't hurt anything. Just don't forget to power down any UPS's.

 

[JD]

Normally there is an ordered shutdown and startup. Down by going small to large and up by large to big loads. This reduces the surge current and the chances of nuisance breaker trips. I'm a little surprised there are no plans for this; surge / sudden magnetic increase can nuke a transformer.

I don't know. Blackouts happen all year long. Some very short when the electric company is transfers loads, longer when a traffic accident or storm takes it out. Most systems shrug this off. More of a problem is if one phase leg goes down tripping 3 phase protection gear. Kind of makes in house procedures null and void. Important equipment can be battery backed-up, but that's not realistic for heavy loads. Even gene transfers induce short blackouts.

 

[blackisthenewblack]

A venue that I worked at was evacuated due to potential flooding last year overnight, so no one was in the building to turn things off and when they got back a week later power was back up already, but no one thought to talk to the theatre company about their power needs. Needless to say, they were finding dead dimmer modules for about 4 months after as they were hanging lx for different shows.

 

[AlexDonkle]

Might want to post large warning signs on all entrance doors into the theatre. You'd hope no one would enter, but in case someone wants to "go check something really quick" they shouldn't attempt to walk through the theatre in the dark. Lots of accidents have occurred when a light switch either wasn't there or didn't work, and people walked into the dark room anyway. Possible include info on where the ghost light switch is and which door to access it from if it's fed from a separate power source.