Multifamily building - ground bar for IT closet

[anbm]

6 story multifamily / apartment building, main telecom room is on ground level, each upper floor has a small IT closet,
Is telecommunication ground bar required in each IT closet per any codes? TIA-607 or other telecom./communication codes?
Thank you!

 

[Buck Parrish]

NEC does not require it, You're building specs might.

 

[hbiss]

Is telecommunication ground bar required in each IT closet

What would you need it for? Answer is no.

-Hal

 

[anbm]

What would you need it for? Answer is no.

-Hal

Maybe bond any metallic IT racks, equipment in room (if exist) to it... thought this is required by some kind of telecom standards, or practices but I couldn't find it...

 

[suemarkp]

What is going to be in these rooms? Some network switches come with ground lugs for grounding to the ground bar that may or may not be there. Typically, if shielded cable is used, it can be helpful to have that bar. But really, as long as there is a circuit there with an equipment ground, that should provide what they need if they even need it. We have hundreds of Cisco switches here and none of them have the ground lugs installed. They are only grounded through their power cord, whether shielded cable or UTP. I don't see a requirement in the manual to connect that lug to a ground, and many manuals are silent about what to do with ground lugs on their equipment.

I doubt there is a building code that requires it. If you are working under plans, the plans may reference some TIA or other standard where they require this. To me, if they really want it, it should be on the drawing. Notes referencing standards should be more installation guidance and not a laundry list of what all you need to provide unless they reference specific sections.

The only thing I can think of where it would be helpful is if there are any antennas outside that come directly into these rooms (e.g. cell phone repeater, Sat TV dish). Those need to have a GEC available for grounding the antenna, lead in cable, and/or lightning arrester. This would most likely only be the room on the top floor.

 

[abrace]

We work in a lot of IT closets in MDUs and such, and I can count on one hand the times i've run into a proper ground bar.

In our facilities we always install an main ground bar, and sometimes an auxiliary ground bar as well in another room if we have gear in multiple rooms. We always put up a ground halo overhead and ground every rack. Each rack also has a vertical ground bar from top to bottom that all the servers and network switches are also grounded to. Most of them have ground lugs on them, and they are there for a reason. The majority of IT people don't use them with the argument that its grounded through the "power cord", but our interpretation of 250.110 is that if the equipment is "fastened in place", which it is if screwed into a rack, that it needs to be grounded...and thats why the lug is there in the first place.

 

[don_resqcapt19]

We work in a lot of IT closets in MDUs and such, and I can count on one hand the times i've run into a proper ground bar.

In our facilities we always install an main ground bar, and sometimes an auxiliary ground bar as well in another room if we have gear in multiple rooms. We always put up a ground halo overhead and ground every rack. Each rack also has a vertical ground bar from top to bottom that all the servers and network switches are also grounded to. Most of them have ground lugs on them, and they are there for a reason. The majority of IT people don't use them with the argument that its grounded through the "power cord", but our interpretation of 250.110 is that if the equipment is "fastened in place", which it is if screwed into a rack, that it needs to be grounded...and thats why the lug is there in the first place.

That section only requires a connection to an EGC. A 3 wire cord plugged into a receptacle that has an EGC, meets the code requirement. Nothing in the code supports the idea that an external grounding connection is required.

 

[abrace]

That section only requires a connection to an EGC. A 3 wire cord plugged into a receptacle that has an EGC, meets the code requirement. Nothing in the code supports the idea that an external grounding connection is required.

We can agree to disagree.

#1 The power cords are removable, yet the equipment remains in place
#2 The power supplies are swappable when they fail, yet all the rest of the gear in the rack remains energized
#3 The manuals for most of the gear refer to this ground lug as the "chassis" ground, and generally the instructions tell you to ground the chassis using this ground point. The 3 prong C13/C19 is usually referred to as "power supply ground". Don't the instructions have to be followed per the NEC (I forget the code reference).

 

[suemarkp]

If the cord is removable, what is likely to cause the rack or chassis to be energized?
If it s hot swap power supply, there must be more than one cord. The other power supply is still grounding it.
I've not seen ground lugs on servers, only network switches. Never seen anything in the instructions that references them.

 

[tom baker]

The NEC is the minimum standard. A power cord provides the necessary bonding. An external bonding connection may provide some additional benefit, and this requirement may date from older type of telecommunications systems, BICSI has recommended standards if you want to dig deeper

BICSI advances the ICT profession

BICSI supports advancing the information and communications technology (ICT) community and is a global leader in ICT education, certification, and standards.

www.bicsi.org

 

[tom baker]

That section only requires a connection to an EGC. A 3 wire cord plugged into a receptacle that has an EGC, meets the code requirement. Nothing in the code supports the idea that an external grounding connection is required.

Its important to recoginz

We can agree to disagree.

#1 The power cords are removable, yet the equipment remains in place
#2 The power supplies are swappable when they fail, yet all the rest of the gear in the rack remains energized
#3 The manuals for most of the gear refer to this ground lug as the "chassis" ground, and generally the instructions tell you to ground the chassis using this ground point. The 3 prong C13/C19 is usually referred to as "power supply ground". Don't the instructions have to be followed per the NEC (I forget the code reference).

Its important to recognize the difference between grounding and bonding. Bonding is far more important. Please see the article 100 definition of ground. Often manufactures don't understand bonding and grounding. Mike Holt has said 99% of most grounding information is wrong

 

[abrace]

If the cord is removable, what is likely to cause the rack or chassis to be energized?
If it s hot swap power supply, there must be more than one cord. The other power supply is still grounding it.
I've not seen ground lugs on servers, only network switches. Never seen anything in the instructions that references them.

All true statements, and sometimes they aren't. It depends. Most racks have gobs of gear in them, removing the cord(s) from one server does not deenergize everything in the rack.

As to servers, any NEBS compliant server is going to have a provision for a chassis ground. Anything manufactured for use in telecom most likely has one.

Bellcore/telcordia/tia all go far beyond NEC in these areas, to the point of being crazy IMHO, making sure all the ground whips curve gently in the direction of travel of the cable,insulation/isolation pads under the racks to force any current flowing over the ground to go through the halo.

Silly? Probably, but it is what it is in telecom.

 

[abrace]

Its important to recognize the difference between grounding and bonding. Bonding is far more important. Please see the article 100 definition of ground

You're right. I use the term interchangeably and I shouldn't.

 

[zbang]

Most racks have gobs of gear in them, removing the cord(s) from one server does not deenergize everything in the rack.

No, but all of the other cords provide a fault current path for the energized equipment.

As to servers, any NEBS compliant server is going to have a provision for a chassis ground. Anything manufactured for use in telecom most likely has one.

Sure, but does it need one? I don't think I've ever seen that terminal connected except for an actual telco installation and not always then.

All that aside, it's fairly unlikely that an apartment block is going to have more than maybe 6RU worth of "IT" equipment, and it's also likely that all of that will have either a 3-conductor supply cord or an external listed PS (e.g. "wall wart") and won't need bonding.

 

[petersonra]

Exceeding the minimum requirements does not always mean that you get a better installation or that it will perform better. All it guarantees is that it will cost more. As far as bonding goes the bare minimum is more than adequate to trip the overcurrent protection device in the case of short circuits. That's what it's there for.

The idea that you can get rid of electrical noise by More grounding and bonding is just generally not true.

The idea that somehow better bonding and grounding will eliminate damage from surges or lightning strikes is also mostly not true.

That leaves you pretty much the only reasons to do more grounding and bonding than the code requires as a bare minimum is because somebody is paying you to do it or you just don't know any better.

 

[grich]

...Bellcore/telcordia/tia all go far beyond NEC in these areas, to the point of being crazy IMHO, making sure all the ground whips curve gently in the direction of travel of the cable...

Gentle bends reduces inductance. That matters if the ground cable is having to pass surge currents from, say, a lightning strike. Probably doesn't matter in an apartment building, matters a LOT in a building connected to a 400-foot tower.

 

[grich]

The idea that somehow better bonding and grounding will eliminate damage from surges or lightning strikes is also mostly not true.

Again, probably doesn't matter much in an apartment house, but it matters a LOT in a building connected to a 400-foot tower. Do it wrong, and you can make things worse.

 

[petersonra]

Again, probably doesn't matter much in an apartment house, but it matters a LOT in a building connected to a 400-foot tower. Do it wrong, and you can make things worse.

Which is not a very common thing. For the most part exceeding the bare minimum grounding and bonding requirements serves no useful purpose, but there are some relatively rare cases where it matters. But a typical IT closet isn't one of them.

Incidentally, I would guess your 400-ft tower probably has a highly engineered lightning protection system. It's a good bet that there's some kind of code beyond the national electrical code that describes that kind of lightning protection system and it's requirements.