Data Rack Used Exclusively for UTP Cabling: Is Bonding/Grounding Required?

[inq]

I'm having a difficult time interpreting the NEC when it comes to datacommication racks. Specifically wall racks that will only house POE switches, patch panels, and cable management for Unshielded Twisted Pair CAT5e/CAT6 cables.

Typically we use wall mounted racks for smaller installation. Something like this:

250.96(A) is typically cited as the code section that governs bonding and grounding of racks and enclosures. However, it says that bonding is only required for "[racks] that are to serve as equipment grounding conductors, with or without the use of supplementary equipment grounding conductors".

800.100 also covers datacom bonding and grounding. However it specifically says "The primary protector and the metallic member(s) of the cable sheath shall be bonded or grounded as specified in ".

It would appear that neither of these criteria are being met with racks that are used exclusively for UTP cable installations. This cable type does not have a "sheath" or shield, and does not require grounding. There is therefore no need for a rack to be used as an ECG and therefore would not need to be bonded or grounded.

Is there a code section that I have missed that covers this, and, if not, is my interpretation of the code accurate — is it consistent with how it is normally interpreted?

 

[Hv&Lv]

Aren’t the POE switches grounded? Also the patch panels?

Has someone requested TIA-942standards?

 

[inq]

Aren’t the POE switches grounded?

They are, through the power cord, but let's assume a switch isn't present. It's just a patch panel. What then? Also, if this isn't being used as an ECG then it wouldn't have to be listed. Most/many of these types of wall mounted racks are not listed.

 

[zbang]

Unless it's possible to become energized, it doesn't need grounding, so if the rack only contains patch panels, I'd say it's fine without.
Any powered equipment that has a grounding conductor will also bond the rack it's mounted in.
The only corner-case is a piece of ungrounded equipment with a 2c cord, and if it's properly constructed and listed, I don't see a possibility of that energizing the rack.

 

[inq]

Thanks, is there a code section that covers this? I agree, its common sense that if something can become energized it should be grounded, but i'm wondering if there is a specific code section that I could reference?

 

[ron]

Thanks, is there a code section that covers this? I agree, its common sense that if something can become energized it should be grounded, but i'm wondering if there is a specific code section that I could reference?

250.4(A)(4) tells you to bond when it is likely to become energized. Nowhere in the code does it tell you not to bond, because you can if you want optionally, which happens a lot in a data center.

250.4 General Requirements for Grounding and Bonding.
(A) Grounded Systems.
(4) Bonding of Electrically Conductive Materials and Other Equipment. Normally non–current-carrying electrically conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.

 

[inq]

250.4(A)(4) tells you to bond when it is likely to become energized. Nowhere in the code does it tell you not to bond, because you can if you want optionally, which happens a lot in a data center.

250.4 General Requirements for Grounding and Bonding.
(A) Grounded Systems.
(4) Bonding of Electrically Conductive Materials and Other Equipment. Normally non–current-carrying electrically conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes an effective ground-fault current path.

Thanks Ron,

Appreciate it.

 

[hbiss]

but let's assume a switch isn't present. It's just a patch panel.

With UTP cable connected to a patch panel there is very little chance that the copper of a cable could come in contact with the rack if it should somehow become energized. With STP it's a different story.

So really, it's a judgement call. With racks, even a small wall mounted one like that I would like to see them bonded to ground, but there is nothing in the Code that says you must.

-Hal

 

[petersonra]

It is my personal opinion that article 800 does not cover internal wiring such as what you are describing. It only covers the wiring coming into the building from the utility providing the internet cable or other similar service. Once it connects to your equipment, article 800 no longer applies. Just my not so humble opinion.

I would point out that the unshielded twisted pair cables being used for standard ethernet are class 2 circuits and would need to comply with article 725. I don't recall article 725 requires you to do any bonding for class two circuits.