Is this still a thing?

Learn the NEC with Mike Holt now!
Electromatic

Electromatic

Senior Member
Location
Virginia
Occupation
Master Electrician
I have a water tank/booster station at the top of a mountain where the water is supplied by a pump station at the bottom of the mountain. There is a mechanical pressure switch at the top to call for water. For control at the bottom to turn the pumps on, there is a Wheelock CRT-T-40 telephone relay operating at 90V, 20Hz. The wiring between the stations is a telephone line. Is there a modern way to accomplish transmitting a signal here? The stations are about a mile apart through woods. The telephone line route is probably longer.
phone relay w-cap.jpg
 
If it ain't broke, don't fix it.

Radios and cell phones are subject to jamming, interference, and network failure. The only thing a pair of wires has to worry about are a tree limb falling or someone with a pair of snips.
 
Are you sure the Wheelock relay responds to the phone line ringing? How does the pressure switch, with only a pair of contacts call that line? My guess is there is a dialer like an elevator phone with its button rigged to work off the pressure control contacts.

There is actually a simpler way. Phone company can supply a dry pair from the pumping station to the water tank. Then you only need a relay at the top and the pressure switch contacts with a small power supply on the other end at the bottom.

-Hal
 
hbiss said:
Are you sure the Wheelock relay responds to the phone line ringing? How does the pressure switch, with only a pair of contacts call that line?
Click to expand...
"telephone line" could just be a long dry pair and that the sender applies the ring voltage which activates the wheelock relay at the pump. Using a sensitive relay like that makes sense for the distance and simplicity.
 
I once had a large garden apartment complex that had multiple boiler rooms. The super wanted to monitor the boilers for shutdowns. Not sure how it came about, but when I got there, they already had dedicated dry pair phone lines from each boiler room to the super's work room. I kinda think nobody could make it work. So, I made up an annunciator alarm panel with "sensitive" relays and a DC power supply for each building which is probably still there today.

The thing to remember about dry pairs from the TELCO is that they may not directly run from point A to point B. They could run blocks or miles out of the way to a cross box where they are connected to the pair going to the destination. Or they could even wind up at the Central Office where they are connected.

Back in the day (and probably to an extent today) there were audio and video pairs also. Audio was sent from the studio to the transmitter site and background music was distributed to stores and restaurants.

-Hal
 
Last edited:
Is there power going to the top? If so, you could use a line carrier modem, also known as a “power line carrier” (but that gets confusing in our industry because PLC means something else). It superimposes a communications signal onto the power wires that are going there anyway. The hardware at either end is more expensive, but no need for another wire nor is it subject to the issues with radio transmission.
 
Is there power going to the top? If so, you could use a line carrier modem, also known as a “power line carrier” (but that gets confusing in our industry because PLC means something else). It superimposes a communications signal onto the power wires that are going there anyway. The hardware at either end is more expensive, but no need for another wire nor is it subject to the issues with radio transmission.
 
Jraef said:
Is there power going to the top? If so, you could use a line carrier modem, also known as a “power line carrier” (but that gets confusing in our industry because PLC means something else). It superimposes a communications signal onto the power wires that are going there anyway. The hardware at either end is more expensive, but no need for another wire nor is it subject to the issues with radio transmission.
Click to expand...
Home Depot tried that with lighting controls, shedding certain fixtures. Never worked right, and they eventually abandoned it. Don’t remember who the manufacturer was.
 
hbiss said:
Back in the day...
Click to expand...
I worked on a lot of that kind of stuff :D. One company had probably 250+ dry pair "burglar alarm" (BA) lines, guaranteed to pass 30 baud switched DC but were fine with Bell 103 modem signals; max length was usually under 15k ft. Also some "foreign data" (FD) lines, which were provisioned for audio-freq data and might be four-wire outside the customer prem. (We had the unpublished local test desk number on speed dial.)

Another client had a few sets of broadcast loops (mostly flat from maybe 40 to 15k Hz but beware of phase shift) plus some BA lines for monitoring and talkback.

Fun times.
 
ptonsparky said:
Our local village had a dedicated line until they switched to radio.
Click to expand...
A 'outside security audit firm' was hired to check for information and building systems security on a large campus here, and they (with permission) demonstrated how easy it was for them to disable and take over several wifi and radio systems from a parked car.
I am now tasked with helping the IT dept revive several long telephone cables that did similar functions,so they can ditch the insecure wifi systems LOL. These cables probably go back to the 80's or older and most still work fine.
 
WD40 said:
A 'outside security audit firm' was hired to check for information and building systems security on a large campus here, and they (with permission) demonstrated how easy it was for them to disable and take over several wifi and radio systems from a parked car.
I am now tasked with helping the IT dept revive several long telephone cables that did similar functions,so they can ditch the insecure wifi systems LOL. These cables probably go back to the 80's or older and most still work fine.
Click to expand...
Good. Glad they found the security issues. Now, when was the last time you changed locks on the doors, keys, etc? Is it done each and every time an employee change occurs?
 
zbang said:
If the telephone line based system is still working, why replace with something "modern"? As long as the line is intact, the AC relay system will outlast a radio system by a fair while.
Click to expand...
I knew a retired guy that worked for 'Western Electric' the company that made all the landline gear for AT&T he often bragged even their most basic underground equipment was tested by the military to withstand nuclear fallout so the military could still communicate via land lines deep underground after an attack.
 
You must log in or register to reply here.
Top