ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
Happy Thanksgiving
by gfretwell - 11/24/20 05:44 PM
What does your work place look like?
by HotLine1 - 11/23/20 03:35 PM
Where is Everyone?
by Lostazhell - 11/21/20 04:17 AM
Ground fault remover :-)
by dsk - 11/21/20 02:47 AM
Work Gloves?
by gfretwell - 11/20/20 10:17 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
1 registered members (Scott35), 17 guests, and 15 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Telephone static #159794 01/28/05 12:20 AM
Joined: Sep 2003
Posts: 114
B
bwise121 Offline OP
Member
An electric gate company installed a gate at a residence. The gate had a key/voice pad at the enterence of the residence for communication. When they were finished the owner had static on his phone lines. I saw that the install used non-direct burial phone lines in the ground and they ran it right next to a 120 Volt feed. Although the 120 is in pvc conduit, could it still cause interference? What are the rules/codes for installing telephone lines near electricity?

thanks,
Byron

Study Guides for VDV / Structured Cabling Installers

Voice, Data, Video, (VDV) Fiber Optics, Communications, Low Voltage,
Fire Alarm, Electronic Security Systems Installations & Related

NTC Low Voltage Training & NICET Exam Study Guides
Low Voltage Training & NICET Exam Study Guides

Re: Telephone static #159795 01/28/05 12:42 AM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
2" is minimum,(800.52(A)2) however more is wise, especially parralel.

But sure it is "static", and not "hum"?

Static can be many reasons. Loose / dirty connection, bad equipment, a whole range of things.

Hum could be induced in the way you described. Especially in PVC or cable. Metallic conduit would afford some shielding effect. Or, the use of shielded phone cable. Both would reduce it to some degree.

Isolate the noise by removing elements of the phone and gate wiring, or shutting off the gate to see if it goes away. If there is an intercom to the gate via phone that could be an issue too.

Wish you luck...


Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: Telephone static #159796 01/28/05 10:00 PM
Joined: Dec 2002
Posts: 1,250
D
djk Offline
Member
Also remember that a long run of cheap unsheilded phone cable is much more liable to pick up interference from whole variety of sources not just AC cables. It should ideally be properly sheilded if the cable's running a considerable distance to the gate.

Re: Telephone static #159797 01/28/05 11:36 PM
Joined: Dec 2003
Posts: 886
H
hbiss Offline
Member
It would be impossible to say what the problem is from the information you give.

I doubt the fact that the cable is not of the direct burial type would be an issue at this point- I'm assuming that it only has been there a short time. It will fail eventually to be sure.

We need to know if this is static as you say or hum. Static would not be caused by proximity to the 120 volt cable, hum would be a possibility.

What is the phone setup in the house- stand alone phones or a system? How many lines and do all lines have the static? How was the gate phone connected to the phones or system?

-Hal

Re: Telephone static #159798 01/29/05 11:01 AM
Joined: Sep 2003
Posts: 114
B
bwise121 Offline OP
Member
Many thanks for everyone's responses. The owner said the problem was static with a hum. I'm not sure if he is right. I suggested for him to assume the line from the house is okay and have the gate company just splice a new wire from the feed from the house to the control pad at the gate just to see if the problem is resolved. Sure enough, that fixed it. The little jumper is only 15 feet long, so somewhere between those points is the problem. Still not sure what it was.

Thanks to all,
Byron


Featured:

2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
BEAMEUP
BEAMEUP
WA
Posts: 27
Joined: December 2004
Show All Member Profiles 
Top Posters(30 Days)
Trumpy 9
Popular Topics(Views)
271,917 Are you busy
205,789 Re: Forum
193,886 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3