Telecom Grounding

Status
Not open for further replies.

low-wattage

Member
Location
Pennsyltucky
New steel building is built - steel framing, all I-beams and purlins, common around here for warehouses, industrial, etc. There is a mechanical room housing electrical service entrance etc., and approx 200' away, a wiring closet for telecom. The wiring closet has PVC out to the manhole at the curb for CATV and phone service; the demarcation will be in the wiring closet. edit - Wiring closet has its own circuit for power for network and communications equipment, but no subpanel.

A bonding jumper is installed from the column nearest the wiring closet, approximately 50' away, to the backboard in the wiring closet. It is #6 stranded uninsulated open conductor, bolted to the flange of column with a screw on lug. In the wiring closet, it is terminated on a clamp on bus bar, looks like an intersystem bridge typically seen at service entrances - a pass through screw on lug for the #6 jumper, and available screw on lugs for the catv and telco.

Obviously a TIA 607 compliant system was not specified or installed, and will be considered. In the mean time, I am concerned with basic compliance and protection. The AHJ has no requirements other than NEC 2008.

Thanks in advance for your thoughts.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
I've had big problems grounding to building steel. In one case there was an intermittent 50 volt differential (that developed some years after installation) between the telecom ground bar and the ground pin on the electrical receptacles. Equipment was destroyed. I always recommend running the ground back to the service. Code requires all such grounds to be bonded together and I don't think building steel qualifies as a bonding jumper even if it is bonded itself.

-Hal
 

JFletcher

Senior Member
Location
Williamsburg, VA
New steel building is built - steel framing, all I-beams and purlins, common around here for warehouses, industrial, etc. There is a mechanical room housing electrical service entrance etc., and approx 200' away, a wiring closet for telecom. The wiring closet has PVC out to the manhole at the curb for CATV and phone service; the demarcation will be in the wiring closet. edit - Wiring closet has its own circuit for power for network and communications equipment, but no subpanel.

A bonding jumper is installed from the column nearest the wiring closet, approximately 50' away, to the backboard in the wiring closet. It is #6 stranded uninsulated open conductor, bolted to the flange of column with a screw on lug. In the wiring closet, it is terminated on a clamp on bus bar, looks like an intersystem bridge typically seen at service entrances - a pass through screw on lug for the #6 jumper, and available screw on lugs for the catv and telco.

Obviously a TIA 607 compliant system was not specified or installed, and will be considered. In the mean time, I am concerned with basic compliance and protection. The AHJ has no requirements other than NEC 2008.

Thanks in advance for your thoughts.

You are dealing with article 800 (phone) and 820 (catv). Under the 2008 NEC, both sections xxx.100(A), the grounding conductor must be insulated, and protected from physical damage(8x0.(A)(6). Look at those sections, and 800/820.100(B)(1).

250.52(A)(2) allows building steel as a ground.
 

Smart $

Esteemed Member
Location
Ohio
take a look at 250.94
No matter how I look at the objective, I believe a bonding jumper run all the way to the service equipment [intersystem bonding] location is required.

...
250.52(A)(2) allows building steel as a ground.
That specifies how it can qualify as a grounding electrode, nothing else.

I cannot find anything which permits building steel, even when qualified as a GEC, to be used as an intersystem bonding jumper.
 
Status
Not open for further replies.
Top