in-wall transformer options

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  #1  
Old 03-24-20, 01:27 PM
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in-wall transformer options

Located in NYS. Have an old wired alarm system that I am going to replace.

Three user panels in the home. All powered via a transformer at the main panel. Looks like a 16.5vDC system on 24AGW wire.

My new system has panels that each use a 5-7VDC 1000mAh transformer. The system is supplied with a "wall-wart" type transformer. The idea is to run the low-voltage wire inside the wall and pop it out near an outlet where the transformer can be plugged in.

This might work for me on one of the panels. On the other two panels, it's not al all feasible. I need an "in-wall" option.


All panels have AC power available nearby (via gang boxes with 2-3 switches). I am sure I could tap into those and get unswitched AC.

Are there any in-wall transformers that could supply the needed 5-7vDC so I avoid wires sticking out of the walls?

I also considered the possibility of trying to use the existing panel wiring. Should be easy enough to track down which wires go to which panel. The problem is the wire gauge. The new system states 18AGW wire for the power and it looks like existing wire is only 24

I thought about trying to use the existing wire to help snake new wire through the wall.That won't work. Everything head to the basement along exterior walls. Basement is finished and there is no access.


Ideas or suggestions are welcome.
 
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Old 03-24-20, 02:40 PM
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That 16.5v transformer that you located sounds like its's for the doorbell. It should be wired in #18 wire. Most alarms systems have always run on wall warts.

If the wire runs are short you may be able to get away with smaller gauge wiring.
Since DC requires diodes and a capacitor....... you won't find an in wall DC supply.
 
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Old 03-24-20, 04:19 PM
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Thanks for the info.

The 16.5v transformer information is taken from the old alarm system documentation. That's what the system specs list for the transformer. The alarm keypad has a 24g wire in the harness going which is labeled as 12vDC. Moot point since the new system keypads have a max of 7v,

My system is about 20 years old and still a very common one in this area for both residential and commercial settings. I've never seen a professionally installed system with wall-warts for each keypad. The idea of wires poking through holes in the wall seems odd and impractical in most installations. Guess my area is atypical.

If I can't do an in-wall or gang box transformer, the runs will be too long for the lighter wire. That rules that out.

The new alarm panel has mounting holes compatible with a double-gang box. Since I have access to very nearby AC in the wall, I'm thinking about a recessed receptacle behind the box. I have to make sure the wall-wart will fit. If so, I could plug in there and mount the panel on top.

Does that sound like a practical idea?



 
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Old 03-24-20, 04:31 PM
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There aren't wall warts for each keypad. The system has one plug in transformer and battery backup.
The keypads would be connected to the alarm panel with four wires. You could double up the pairs.

I don't know of any way to properly install a wall wart inside the wall. They make recessed plates but that won't be deep enough.
 
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Old 03-24-20, 05:03 PM
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https://qolsys.com
https://www.alarmgrid.com/products/honeywell-l5200
https://www.alarmgrid.com/products/2...gig-gc3pk-ltev

etc.

In these, and other wireless alarm systems, the keypad is the alarm panel. Each keypad requires it's own individual power source, which is provided by the manufacturer as a wall-wart. If you are hiding the keypad/panel in a closet, the wall-wart isn't an issue. If you have it in your foyer next to the front door, a wire draping along or poking through the wall is not, in my opinion, practical.

I've seen some pretty deep AV recessed receptacle plates. You are probably correct that the wall wart won't' fit. I have to find the exact measurements. As I recall, it wasn't as large as some. My wall-wart phone charger would fit and that puts out 5v through USB. There has to be something out there small enough.

If it does not fit, it obviously won't work. If it DOES fit, I am asking if there is a safety or code reason why this should not be done?
 
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Old 03-24-20, 05:06 PM
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May be an access panel method will work out for you?
You could have an outlet inside of the wall and plug your power supply in there. If you can make the hole small enough, alarm system might cover the hole.
If not, you can cover the hole with some sort of access panel and mount your alarm system on the access panel.
If you are good at wood work, you can make a good access panel with some wood panels.

Or, something like this might work ..
https://www.amazon.com/Construct-wal.../dp/B00ARIRI9Q


Extending wire on such a low voltage power supply is not recommended unless it is very short run. There will be too much of voltage drop. Especially with DC.
About 20 ft is maximum I would even try..

--- EDITED ---

Looking at installation manual of alarm system you linked, it says 25 ft maximum with 5vDC and 100ft maximum with 7vDC. All with 18AWG wire.

How were you planing on installing transformer if you could get one? There really aren't any "in-wall" transformers because you cannot bury them in the wall. It must be accessible. That is why it is usually installed in unfinished area.

Does your existing 24AWG wiring have any extra strands of wires? You may be able to getaway by doubling up the wires and using 7vDC.


https://www.amazon.com/SMAKN%C2%AE-C...3202770915A7BF
This might work out as well if you replace existing transformer to 24v AC.
I doubt your existing 16.5V transformer can supply enough current over such a thin wire.
 

Last edited by lambition; 03-24-20 at 05:22 PM.
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Old 03-25-20, 07:28 AM
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Was typing a long response and then the page randomly reloaded and I lost everything.



Short version... I think the combining existing wires idea may work. I'm going to trace the keypad harness wires back to the panel. If I can find enough to work with, I'll go that route. The Quolsys unit I am looking at comes with the 7vDC transformer, so I could put all keypad transformers in the utility room where the old alarm master panel is.

Thanks to you and PJMax for pointing out that wires can be combined. I didn’t realize that was okay.

If that idea won’t work, I’ll have to look at a large recessed outlet box or something like the access panel you linked to.

I’m curious about the voltage step-down device you linked to. Would that sit in the gang box behind the keypad and take the feed from the existing 16.5vDC transformer wire? Just trying to wrap my head around how that works.

Thanks for the help.
 
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Old 03-25-20, 07:55 AM
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I’m curious about the voltage step-down device you linked to.
It is basically just a step down power supply circuit with built it rectifier.
Since it is low voltage, you don't need to put it in the junction box. You could attach this to back of your alarm control panel and maybe cut a little hole on the drywall to make space for it.
Existing 16.5V may not supply enough current. I'd go for at least 24V.
 
 

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