This is a basic method to add an external keypad to a single door access system, the system itself is in place and is operated with wireless keyfobs, while it works quite well the owner having locked herself and a coworker out while on a smoke break, minus a keyfob now wants a second way of access.
The security problem this introduces is, most single door access keypads are self contained and if not tampered properly are only two screws away from being bypassed, yes tamper resistant screws can be used to retain the keypad, but I have as a matter of necessity haven't found a single one I couldn't back-out with a good pair Klein dikes and if I can do it, anyone can.
So what follows is a inexpensive but practical method if installing such a keypad on a secure manner.
NOTE, many jurisdictions require a back-box for all low voltage devices, where connections or splices are utilized, such was not required in this application, but if it was, a Sawzall and an Raco old work box quickly solves that problem.
The first step was to score and chisel through the concrete based siding, then a 1 1/4 inch hole was drilled through the outer wall to provide enough room to get a D-Versi bit up past the insulation and drilled through the header. Once there, a helper up in the crawl space, if he can reach the bit, will attach a 2 conductor cable to the tip of the bit (there is a hole in the tip) and it will carefully be pulled out bringing the cable with it.
If he cannot reach it then we go fish, I take a 20 foot of a standard 1/8 inch fishtape with a 1/4 inch loop on the end and following the path cut by the bit eventually get it up in the crawl space and sometimes by flipping it I can get it to push toward the center of the building, if not the helper with another shorter hank of a fishtape with a hook on the end will fish and grab and pull my tape toward him.
Anyhow, the loft had almost walking room up there, so this pull was very easy.
This shows the keybox roughed in.
Note to the right, a standard "39" series alarm contact has been attached to the structure, more on that soon.
Now the keypad I selected is an IEI/Linear 212w, which the manufacturer states is weather proof, but that only applies to the front of the keypad, if installed in a standard single gang rain-tight box the only thing keeping the keypads electronics from getting soaked is the gasket which commonly fails, IEI has added a raincoat but that doesn't solve the problem.
My solution is to use an Arlington Industries DKB55W surface mount enclosure, these can be had for a fair price and do a heck of a job protecting the keypad form both the elements and observers.
The keypad is fastened to the box with standard #6 SS screws with Nyloc nuts on the back just to frustrate someone trying to use a flat bladed screwdriver to remove the keypad.
It's also worth noting a 1/4 inch magnet has been Epoxied to the side of the keypad.
With the back of the box completed and the wiring in place it was time to connect everything.
Multi-conductor keypad and tamper wiring tinned and spliced.
A close up of the dual wall heat-shrink, note how it fills the termination preventing any moisture from wicking up into the jacket of the cable.
And the wiring to the keypad, look carefully and you might note the power is wired backward, a mistake that was found and cleared.
And now to the control. It is a very simple device consisting of a single relay wired in what, depending on who you talk to, is either a "stick" relay or "drop" relay, which it is matters not because in the security world the terms are interchangeable.
The theory of operation is take a relay and wire it's normally open contacts in series with it's coil, in that condition it cannot pull in even with power applied until a shunt or switch is closed from power to the NO terminal of the relay and the it will pull in and "stick".
Wire the coil in series with the protective loop and you have a very basic alarm system, open the loop the relay "drops" out and it's secondary contacts can be used sound an alarm or in this application isolate the keypad from the access control.
In this application that shunt is a front mounted IDEC illuminated NO pushbutton.
On the security side, if the keypad or box is pulled the magnetic switch opens/drops out, this cuts power to the relay causing it to drop out cutting power to the keypad and with it's secondary contacts isolates the request to open trigger to the access control, this prevents someone with a bright idea from going any further.
The wrap up was the usual cleanup and touchup, I caulked around the enclosure and then once dried used a quart of base white tinted to match the wall to finish up.
Wayne
