I am looking at some electric door strikes that are 12vdc 800mA each (3 to 4 strikes will be in the system), does anybody know of a power distribution that supports this amperage? I bought an ELK system, but their distribution at max is 450mA. OK, here is where I will sound as ignorant as I am at this point, can I splice two 450mA terminals for 900mA for 1 door strike?
Power distribution question....
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Steve
Senior Member
The Altronix power supply looks perfect and with 4 amps. I would have plenty of power. However, here is where I show my total ignorance (and a regret for taking Chemistry in instead of Electronic Engineering for my BS). If each strike takes 800mA, wouldn't the extra power fry them or does the "electronically regulated outputs" keep that from happening?
Steve
Senior Member
An EE can explain it better, but the 4A is the max it can output. The strikes only draw/pull what they need. The only thing is you can't have devices that draw more than the supply can put out. So, you could have a 100A supply powering 1 strike, no problem - just very underutilized. I also like to plan around 80-85% utilization. That is, add up all the power draw and that should be no more than 80-85% of the supply capacity. But I just like that extra cushion but in theory you should be able to draw full amount.
BraveSirRobbin
Moderator
A lot of good advice here and Steve's explanation above is excellent. 
I think though for something as important as door locks you would want to get a distribution system made to handle its current needs rather than use combined outputs from a source such as the Elk's distribution unit. Nothing wrong with that methodology mind you, but you would do this in a case where maybe most of your devices were low current and you had one device that exceeded the single output capability.
Since you have four strikes, it may make sense to get a unit with a built in distribution block designed for its current needs. Doing a quick search I found THESE P3DC units from Automated Outlet.
I also found THIS four station 12 volt four amp unit with one amp individually fused outputs.
You may want to consider your future needs as well (will you add more strikes? will you obtain security cameras with IR lighting? etc...).
Make sure you use the correct wiring gauge as well. You should size the wiring to the fused capability of the supply. For instance if you have a four amp fuse going to a strike, you would run a gauge of wire that is rated for four amps even though the actual strike will only draw around one amp.
You can always make your own distribution unit as well using in-line fuse holders and screw terminals. It's not nearly as 'neat' as a distribution block though.
Just some thoughts...
I think though for something as important as door locks you would want to get a distribution system made to handle its current needs rather than use combined outputs from a source such as the Elk's distribution unit. Nothing wrong with that methodology mind you, but you would do this in a case where maybe most of your devices were low current and you had one device that exceeded the single output capability.
Since you have four strikes, it may make sense to get a unit with a built in distribution block designed for its current needs. Doing a quick search I found THESE P3DC units from Automated Outlet.
I also found THIS four station 12 volt four amp unit with one amp individually fused outputs.
You may want to consider your future needs as well (will you add more strikes? will you obtain security cameras with IR lighting? etc...).
Make sure you use the correct wiring gauge as well. You should size the wiring to the fused capability of the supply. For instance if you have a four amp fuse going to a strike, you would run a gauge of wire that is rated for four amps even though the actual strike will only draw around one amp.
You can always make your own distribution unit as well using in-line fuse holders and screw terminals. It's not nearly as 'neat' as a distribution block though.
Just some thoughts...
BraveSirRobbin & Steve, thank you! I can hardly believe how much help I have received from this forum in just 24 hours!
I kept searching for power distribution and didn't realize they can also be called power supplies. The four channel one looks perfect and I may jump to the 8 out of the door for camera expansion down the road.
I kept searching for power distribution and didn't realize they can also be called power supplies. The four channel one looks perfect and I may jump to the 8 out of the door for camera expansion down the road.
WayneW
Senior Member
One key point here, is, are all these strikes energized at once (ie constantly, 24/7)? or are they momentary with a very low risk two ever being on at once?
To me, a door strike is a momentary thing, but just wanted to make sure as some are always on.
drozwood90
Senior Member
Doesn't elk have a relay board that's controlled by outputs? If so, you can just buy a 12V transformer from Home Despot/Menards/whatever, wire it up to the nearest junction box in the ceiling and then run it down to a distribution block that goes into the output side of each relay.
Great, that solves another problem, I was trying to determine how I would 'turn on' the power when the key fob was detected. That sounds like it will work.
I ended up buying a camera power distribution box as I plan to install camera's at some point. I'll pull the wire now and add a camera at a time.
tmbrown97
Senior Member
one thing to point out - I'm not sure if the elk relays have some sort of overload protection, but it still wouldn't be a bad idea to add a fuse as well. One thing I've done in the past is wire in the in-line blade-fuse holders - but instead of a normal fuse, I found self-resetting circuit-breakers that'll fit the same holder. That way even if it does trip for some reason, once the overload condition is cleared it'll reset - it's a few $ more, but a nice added piece to decrease the liklihood of not getting in because of a blown fuse. That said, it's rare that a fuse should blow anyway...
