Filming under AC Power

kwkeirstead

kwkeirstead

Well-known member
I always record using batteries but now have a project where I will not have enough batteries to complete the job.

I routinely use Uniterruptable Power Supplies (online/double conversion) for computers I have.

How many of you record using electrical grid power and how many use a UPS?

I can understand the temptation not to carry one of these around as they are quite heavy (a UPS is not to be confused with a surge protector strip and it's important to state that most UPSs have some ports that only provide surge protection so you would not want to plug into one of these ports).

The reason a UPS is heavy is it has to have a transfotmer (from the wall, the UPS converts AC power to DC which charges a battery in the UPS, then you invert back to AC) and your camera adapter then converts now isolated, smooth AC to DC.

I have always seen references to possible loss of data if there is a power failure during a recording - an on-line/double conversion UPS removes the concern.
 
I have dragged a UPS to shoots twice. Huge hassle - but solid results.
I knew power was going to be dodgy so it was the right choice. But DANG what a pill! Having to move it around frequently was not fun. We rigged it up with heavy nylon belt-down straps with foam rubber handles so the UPS could be quickly and easily grabbed and moved to the next place it was needed - that was an essential move. We got the strapping with handles at Harbor Freight.

Glad we did it - but for sure, it was the single heaviest object on the shoot.
 
Given how much other equipment (especially lighting) is also dependent on mains power, UPS camera power is typically not an issue on small shoots - without mains power, the shoot is screwed anyway. But yes, I can see that it would be preferable to have at least a couple of minutes of backup power so that cameras, computers etc can be shut down 'gracefully' without corrupting data.

Of course, many cameras and computers have their own internal batteries anyway, which provides plenty of emergency power to shut down.

I'd certainly consider UPS if I had to film in a location with wildly unreliable/unpredictable mains power, probably in conjunction with surge protectors to prevent lights etc getting burned out. But otherwise, it sounds like too much work.
 
I think nearly all sound and video carts I've come across on set have a UPS, I say nearly because I'm not always paying attention to whether or not they have them but I'd be surprised to plug one in that didn't have one. Mistakes happen and electrical equipment doesn't always do what it's supposed to do. If a ground fault occurs it can trip the MCB even on a large generator and then everyone hooked up to it loses power. DIT and VTR should always be on a house line when available, but when there is no house line to be found a UPS is pretty important.

Of course if all you have is a couple laptops it's not as big of a deal since they have their own batteries, but as soon as you introduce devices that run on 120v, you should really have them on a UPS.
 
You did not mention if your camera has a DC power jack. I assume it does not as your description is very thorough, and you would most likely think of the alternative approach. But just in case if it does I will through it in. You could just plug a 12V lightweight power adapter in instead of a heavy UPS. Your camera battery would kick in if AC is gone.
 
Bigger problem with power going out is you can lose the whole clip that was rolling. Even if the lights kick off, you may want the footage shot up to then.

That said, my UPS isn't crazy-heavy, it's a desktop-computer & peripherals size. If I brought it to a gig, I'd find a way to mount it to a heavy tripod dolly. I've got a big manrfotto that has a 3/8 bolt sticking up in the center, I've mounted plywood to that before for weights with a crane shot, should work well. It'll power my mac pro, monitors and drives for 3-4 minutes when there's a shut down.
 
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