atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Trying to filter out noise from an arc-welder?

Verizon's Demarc is nestled between 3 3-phase 460-volt boxes. To add to it, it's about 20-30 feet away from 350-amp AC Tig welders. Everytime someone strikes an arc and starts welding, you hear the crackle on the line.

Anyone have any ideas for a filter to cut down on the noise? Or is stringing shielded cable my best bet for solving this one? Would even that help? Thanks...

Verizon demarc close to power panels is the norm
and that is part of the drill.

Now plan "B" may just be a solution.
If the welders are getting into the system you have to find out where?

It dont have to necessarily be coming from a power source.

Relocate wiring if its close to welders, that is such as station cable, page line, etc.

In order to treat the problem, you have to decide
how the welder is being inducted into the telephone.

You must become a Dick Tracey on this one.
I do wish you happy hunting.

First check that the welder has a good case ground more then half the welder noise I have run into was eliminate by grounding welders. I have also had time where I had to build a shield around the phone equipment

Pretty sure the noise is entering the system from the analog side of the pbx. Digital signals usually clip/drop-out or are unaffected. So that narrows my problem down to the Demarc up to the box, hopefully.

I'm sure it will take a day to find it. Sit out there on a phone and have each welder start welding one at a time till I find the culprit machine. Be easier if there wasn't 18 arc welders. In further talks with the shop manager they have had some bad problems before with grounding on the welders. Guess I'll have to see if there is metal stacked up on the welder's that is touching the building. Probably the most likely culprit for noise. Their old partner system had a few burnt CO ports on it.

On a side note, they blew up a transformer on the line the other day. 12-foot flames shot out the top and burnt a tree down. Verizon and BrightHouse (CaTV) had to patch a section of cable cause of it. The pbx survived with flying colors Although their linksys router bought the farm. The noise existed before all of this though.

Use shielded wiring, ground ONE end (at the SNI).

Multi-phase has a "wild" leg, it can cause a lot of noise if not "matched" to the input of the welder.

My $.02

Try this link, https://www.sandman.com/rfbull.html

Well, I will try grounding the 2-pair that are extra. The cable is already Cat5e. Calling supply house to see what STP is gonna run.

I going to try snapping a few ferrite cores on the line and see if that helps.

This is one application where fiber is perfect...
however probably not practical in your situation.

I could consult if you send me a pm with your situation (no charge of course)

- Matt

They've found the 2 welders that are bleeding on ground, however they aren't interested in having them fixed. Something to do with bad shielding or ground internally.

So they put up with static.

Wow... what a customer! They prefer static on their phones vs fixing shielding or a bad ground!

Go figure! :-D

Cheers,
Matt