Ground Problem

[FatFndr]

I have a unattached garage and recently ran an underground wire (4 conductor,18 gauge, with shield) rated for underground use. 2 conductors were used for the phone and 2 for a pushbutton switch to open the garage door from inside the house. I experienced static on the phone which fed back into the house to the other phones indicating to me I had a grounding problem. Since the wire was within a few inches of an 8 gauge 240 volt line I had previously run for power to the garage, I figured it was inductive and dug up and moved the cable to a more remote spot. Same problem.

Long boring story short.......it is the automatic garage door opener causing the problem, the phone works fine if the 2 wires connected on the back to a pushbutton switch are disconnected. Using a meter I checked the new cable to ground and found all is well, no shorting at all.......it's when I hook up the garage door opener that I have a problem.

It is an older unit installed around 1995 and is working properly other than causing static (all the time) on my phone.

Is there a cure for this? If I buy a newer model (Sears) will that eliminate my problem? CAn I put a diode somewhere that will help? Ground the case?

Thanks for any help

 

[ArthurPE]

are you saying the 4 conductors (2 phone & 2 door button) are in the same overall sheilded cable? if so, should have used a cable with 2 shielded (phone) and an unshielded pair for the button...

might want seperate cables...

is the shield grounded? try the following and see if it goes away:
ground each end (one at a time)
ground both ends
ground neither end

 

[FatFndr]

Currently neither side is grounded. I'll try grounding it tomorrow and if unsuccessful, I'll drop another cable in the ground for the door opener

Thanks for the suggestions, I was getting a little burned out digging trenches and fighting this problem

 

[ddawg16]

Grounding is NOT going to solve your problem. You are putting a phone line in the same cable as a 24Vac line....and I'm willing to bet that the cable is not twisted pairs.....what you are hearing in the phone line is the 60hz from the 24Vac.

They need to be two seperate lines....and the phone needs to be twisted pair....

 

[Rob_b]

As Dawg mentions, you should run the lines seperatly. The phone line can actually go much higher voltage than 24V. I know the problem is the garage door button in this case. When you run twisted shielded pair wire , you always only ground one end period. Connecting both ends can and will cause a ground loop and bring in noise from anywhere. My thought...get yourself a good cordless phone and end the issue.

 

[kbs2244]

Get a wireless remote for the house.

 

[FatFndr]

Changed to separate cable and grounded the shield on one end, didn't have a twisted pair but......problem resolved. Line is clear and usable with no interference in the main house.

Thanks to all that offered advice, it was appreciated