Subscriber Discussion

Do I Need STP Cable For This Project?

UI
Undisclosed Integrator #1
Jun 05, 2017

I just had a customer contact me to install a bunch of cameras and he had his own employees run shielded cat6. I feel it is overkill to have run this for cameras but I don't think he knew it. 

I have never used or terminated shielded wire.

I dont have any problem with properly terminating these runs like I see on youtube but I am just curious if there is any harm caused by not using the metal rj45 connectors, and then with also not grounding the poe switch that it is run to. I know it defeats the purpose of it being shielded, but when it increases his cost both in time and equipment....

Avatar
Brian Rhodes
Jun 05, 2017
IPVMU Certified

It is unclear whether or not any of the camera cabling runs requiring shielding.  Are any of the runs penetrating outside or near (within 4" - 8") high-voltage lines, electric motors, or lamp ballasts?

Background: STP vs UTP for Surveillance

UI
Undisclosed Integrator #1
Jun 05, 2017

Lets assume not, for now. 

JP
James Pralle
Jun 05, 2017

You must absolutely terminate the shield / drain on both ends of each cable via shielded jacks, patch panels, patch cords, etc...  In the absence of proper termination and a complete pathway, that shield then becomes an antenna of sorts, and as such, an expressway delivering RFI, EMI and every other sympathetic ambient noise in proximity to your cable along its entire route.

(1)
(2)
DP
Donald Peters
Jun 06, 2017
IPVMU Certified

The "antenna effect" has been taught for years but I believe it was proven false a few years back.  Since STP cable is installed, I agree that it's best to bond to ground at least one end of the cable.  Taking both ends to ground will add very little value, if any.  Hope this helps.

Avatar
Brandon Frazier
Jun 06, 2017
IPVMU Certified

Siemon wrote a great article a few years back disproving this. It is a good read. 

http://www.siemon.com/us/standards/Screened_and_Shielded_Guide_7_Antenna_Myth.asp 

(1)
JH
Jay Hobdy
Jun 05, 2017
IPVMU Certified

He started down the path of shielded, you might as well finish it.

 

We all have clients who think they know best and insist on certain items. As long as it is not against code or jeopardizes life safety, and they pay their bills, I roll with it.

(1)
UI
Undisclosed Integrator #1
Jun 05, 2017

does the third prong of an electric plug provide any grounding necessary to finish the job when the jack is properly terminated? Or do I need to buy specific switches that have a grounding screw?

The Customer never planned for this so there is no grounding in place where the equipment will be installed. Do I need to specify him to have an electrician install this? 

UI
Undisclosed Integrator #1
Jun 05, 2017

bump

Avatar
Brian Rhodes
Jun 05, 2017
IPVMU Certified

If the prong is grounded, it only grounds the power supply of the switch, not the devices attached to the switch.  If you want to ground the chassis and ports of the switch, you need to ground it via screw or rack to a ground rod or TGB.

JH
Jay Hobdy
Jun 05, 2017
IPVMU Certified

I believe switches that have metal shields around the port are grounded.

 

I have a Ubiquiti TS-8 here that has the metal shield and I connected a meter to the shield and ground terminal on the back and got solid continuity. 0 ohms.

 

So it is my believe that if the drain wire is connected to a metal connector properly, that drain wire goes to electrical ground on a switch with the metal shielding.

 

 

As far as a plug with ground, that usually means it is grounded. I would use a meter to check hot to neutral and hot to ground.

 

On older buildings it seems like neutral and ground are tied together. New buildings seem to have a dedicated ground.

You wont know the difference unless you check the main panel.

It seems as if a dedicated earth ground is best for electronics but few are going to drive a ground rod so they use electrical ground.

 

From my experience and research, grounding is a whole can of worms in itself.

Avatar
Jon Dillabaugh
Jun 06, 2017
Pro Focus LLC

If the camera and the switch all have metal ports, then you might as well use shielded connectors. If either end does not, then it's a waste. If you are using a patch panel or keystones in between, they also have to be shielded too.

That said, I have yet to find a shielded connector on any camera. Not saying they don't exist, but I haven't seen one yet.

(1)
New discussion

Ask questions and get answers to your physical security questions from IPVM team members and fellow subscribers.

Newest discussions