On Thu, 11 Jan 2007 15:23:29 -0500, wrote:


You are supposed to have a barrier between the 120v side and the low
voltage side. It might be easiest to put all of the 120 in a separate
box and just feed it with the low voltage from the burglar alarm. Have
you looked at Solid state relays? They provide a great deal of
isolation and will work on very low currents from the low voltage
side. Hosfelt, AllElectronics and the other surplus sites sell them

I used to get the AllElectronics catalog, but maybe I didn't buy
enough, or maybe they are all web now.

about as cheap as a regular coil relay. They also have the advantage
that they are essentually an LED on the low voltage side so you can
drive them directly from "logic". The Opto22 and Crydom (and other

I'm actually only powering a reed relay directly from the alarm board
now. What I've been using is a quality brand relay more than rated for
the load, and that is powered by the output of a reed relay that
requires a very tiny input. Either the manual for the previous alarm
didn't say how much current could go through screw #7, or I was afraid
I would make a mistake about how much was used by the relay. But I
was just tremendously scared of burning out that part of the board,
and maybe more, so I made sure the output used was verrry low, by
putting the reed relay in the middle. Using two relays in sequence
seems to me like a Rube Goldberg machine, but there's no noticeable
delay in the light going on, and I think it worked fine for maybe 15
years.

similar types) have the LV and line on opposite ends of the device so
you can arrange a barrier to be perfectly code compliant. If you mount

If that would make me code compliant, have I already succeeded in that
by the method I'm using now? I'll admit that the 12 volt power supply
that powers the alarm (and with the new one is integral with the alarm
board) also powers the circuit with the secondary of the reed relay
and the primary of the output relay.

one horizontally in a 4x4 square box you can install the barrier made
for the purpose.

I just happen to have a couple 4x4 boxes that I'm looking for a use
for. No kidding**. Can I put the 4x4 box in the old alarm box,
which now has plenty of room because it only holds a separate 18 volt
siren driver and the 18 volt power supply?

I'll admit that what I've been using up to know was a metal Band-aid
box lined with cardboard, with all the metal electrical parts covered
in silicone sealant, and arranged so that nothing electric touches
walls of the box anyhow. I guess that's not good enough 8~(


(18 volts makes the siren louder. Even though I'm getting monitoring
this time, I'm a big believer in sirens. After calling my house to
check for a false alarm, the monitoring will send the police, in 5
minutes if I'm lucky. The siren goes off immediately.)

**I think the 4x4 boxes came from the retired alarm guy, who rented a
ministorage unit from a friend of mine. Once in a while she lets me
clean out a unit when they move out and leave things behind (which
they're not supposed to do, of course, and few do.) I'm not sure what
standard she uses to decide when to let me do that. (I'm hoping it's
whenever there is something I would want that she doesn't.) I sold
for a dollar or two or gave away most of the alarm parts last summer.

You just have to cut out the section that fits over
the SSR. The other option is to mount them on the side of a deep box
and fabricate a barrier that screws into the back of the box dividing
the top and bottom. I can send you some pictures of some I have made.

I could do that too, if it turns out there isn't room for the 4x4 box
inside. Or it might even be better, not having to run the wires
through 2 layers of steel. Although then I wouldn't have the second
door.

If it is not much trouble, I'm at mm2005 a.t bigfoot do.t com.