My driveway sensors are wired. They are the CarTell CP 2. The upside of a wired system is obvious- no batteries. The CarTell is a buried sensor than senses moving metal, so no triggers from wildlife.
The downside is you have this huge run of wire out there connecting to electronics at both ends. So you have to do a lot of protection of the electronics.
The wires for my sensor are in a 160 PSI black PE pipe buried 2' down. At the sensor end, you need to come up and go into a box so you can both splice to the sensor and have some transient protection (MOVs or TVS Diodes). Put the sensor in a 3" PVC pipe at an angle so you can have it right at the edge of the driveway, but are working 4' away from the edge if you have to dig it up.
Coming into the house, you have to come in at or near the single point of entry and have gas tube protectors (like the telephone company uses). Then, before you go into any electronics, you have to have additional TVS diodes. Finally, you need to do something with the relay closure you get such as wire it into an automation or security system or connect it to a relay to ring a standard door bell chime.
Regrettably, none of the "normal" automation or home security sites sell a kit with all these pieces so you're left to design and fend for yourself. And things outside with long runs of wire can always have a problem if a lightning strike is too close. Even giving advise on what to do is shaky since eventually a system will have a failure and then since you gave advice somehow you own the problem.
So wired can be done, but you have to know the pieces. This is probably why wireless systems are popular. I hate batteries with a passion, so I went the wired route. Two sensors gives me direction (coming and going). And as far as cost, the wired solution with the right protection tends to cost about $500 for a sensor (if you're digging the ditch) by the time you buy the sensor, pipe, wire, and protection devices. Then you still have to do something with the contact closure from the device. Probably the only good thing about a wired approach (other than no batteries) is the seat time digging the ditch :thumbsup:.
Pete
