Power Pack Locations

[jrohe]

I'd like to get the opinions of Electrical Contractors on ideal locations of power packs for lighting control systems such as Acuity Brands' nLight systems, Lutron Vive systems, etc.

In your opinions, is it better to have the power packs distributed in the area of the controlled lights or is it better to have the power packs centralized in one or more locations?

For example, say I have a small facility with ten offices and each office requires a 0-10V dimming power pack. In each of the ten offices, there is a manual low voltage (24V) switch for ON/OFF/RAISE/LOWER, a 24V occupancy sensor, and a 24V photosensor. Would it be better to:

1. Put one power pack above the ceiling in each office? This would cause the line voltage unswitched wiring to be run to each office, would result in relatively short switch legs, and result in short low voltage wiring runs. Or,
2. Put all ten power packs in an electrical room, adjacent to the associated panelboard? This would cause the line voltage unswitched wiring to be short, would result in longer switchlegs, and result in longer low voltage wiring runs.

In terms of "better," I am hoping the make the installation as simple as possible, minimize the cost, and make future troubleshooting and repairs as simple as possible.

I can see benefits to both methods but am leaning towards #2, mostly because it would likely use less line voltage wiring, the 24V wiring would not require conduit, and the power packs are all easily accessible without having to hunt for them above ceilings.

Thank you all in advance for entertaining this post.

Jason Rohe, P.E.

 

[Kansas Mountain]

Particularly if you are going with Vive, do not put the PowPaks all in one central location, unless you're dealing with a very small tenant fit-out, or something similar. With wireless powpaks, you will still need to be concerned about being within communication range of the input devices like picos, occ sensors, etc. The communication ranges on their spec sheets are highly conservative, but there definitely still is a cutoff point you don't want to cross.

Also, high concentrations of wireless powpaks can create cross-talk between the powpaks if there are too many in one location. Worst case we've dealt with was a contractor that put all of the powpaks in a Hoffman box in the electrical room to keep them organized and easily accessible for replacements. But the system couldn't communicate and had to be entirely re-installed at his cost. Shame too, because the EC's intentions were good and his wiring methods were OCD level neat and workmanlike, just wasn't compliant with the control shop drawings and manufacturer's install instructions