Determining system current draw

[Tinkler]

I am planning an install with many devices attached i.e bellbox, detectors, Internal sounder, keypads expander, dialer etc and have concerns over the system's PS's capacity to cope with the current demand. Regarding this, when determining the current draw on the system, do you work with the quiescent draw of the devices or their "active" demand rating?...or is the quiescent rating added to the active to determine the overall current draw of a device? For example, the bell box draws 15mA quiescent, its sounder 425ma and its strobe 110mA. If an additional PS is required, how would that be integrated into the existing system? Also, how is the back-up battery capacity requirement worked out with regards to the above?

Help would be very much appreciated.

 

[saxondale]

to start with add all the quiesent current, that will detemine if you need a power pack (if you do divide the equipment between the powerpack and the panel) take off the battery charge current (that will be in the manual) and times by 12 to get to the battery standby rating (this all changed recently from the more familiar 8hrs) - obviously you need to calculate the panel and the powerpack seperately, but at your level there shouldnt be any need to link the two together

hope thats clear LOL