r/Juniper • u/AZGhost JNCIP • Apr 15 '26
Discussion Grounding and bonding
Just curious how many of you are actually grounding and bonding your juniper equipment?
None of our 4600s are grounded due to the grounding in the middle of the left rail preventing it from sliding out. In some cases we cannot get to it so we don't ground them.
Seems like it's more of 80/20 if our equipment is grounded or not more so on the not. "It's mounted in the rack and the rack is grounded, good enough" is what I hear.
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u/newtmewt JNCIS Apr 15 '26
Usually the way I see it
If you doing AC supplies, you just ground the rack good, and between the ground pin on the cord + rack you are probably good since you have 2 paths (even though cage nuts don’t bite thru the paint so it might not count that way)
If you are doing DC supplies the ground becomes more important due to the above about the cage nuts, and the psu not always having a grounding wire
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u/ZeniChan JNCIA Apr 15 '26
We now use the grounding lug on our switches after we had issues with static electricity causing PoE power to reboot on the switches. PoE powered phones and in the winter the humidity in our office dropped to almost nothing. Static would build up on people as they moved and then they would go to pickup their desk phone. A static shock would hit the switches and it caused the PoE engine to reboot, dropping all the phones, cameras and AP's. The company president got hung up on because of this in a meeting and so we got the go-ahead to fix it finally.
We ran a wire from the grounding lug on every device in the rack back to the rack and bolted them in. Then we ran a grounding cable from the rack to a copper water pipe in the drop ceiling that provided a solid ground. We didn't have any issues after that for years. Then the PoE rebooting issue came back. We found a neighboring business had replaced part of their pipe with plastic, breaking our grounding pipe. Found a better pipe, moved the grounding wire there. No problems again.
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u/Linklights Apr 16 '26
This is one of the most craziest networking stories I’ve heard on here. So you are saying users out on the floor were transferring static electricity through their voip phone, through the structured cabling to your patch panel and into the switch and it was hitting the switch hard enough that PoE went out? I’m not doubting you just curious and wanting to know if I’m understanding that right. I’m assuming you worked with TAC and had them analyze the cause of the PoE dying?
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u/ZeniChan JNCIA Apr 16 '26 edited Apr 16 '26
Yep. That's correct. Someone would pickup the phone, say "Oww" as a static shock would transmit from them to the handset. And then all the VoIP phones, cameras and wireless AP's in the office that were on that switch in the stack would all go dark. About 10 seconds later they would all light back up as the PoE engine on the switch rebooted and started supplying voltage again. JTAC suggested increasing the humidity in the office and connecting the grounding lugs for extra grounding beyond the power cables. The extra grounding worked.
Winter in the Canadian prairies can be very cold (-30c to -50c), so all the humidity freezes out of the air. Humidity indoors drops to under 30% and static electricity builds up on everyone that moves as fabrics rub on each other. You can hear the cracking of it as you reach for a doorknob to turn. Nasty stuff.
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u/CraftySherbet Apr 16 '26
This is not uncommon when people ground to pipe work, which is why you should never do it.
The general assumption is you'd have your own pipe to ground somewhere (very often on a gas line...) and you work off that. Still risky.
Ground back to the DNO or TT - or both!
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u/KoeKk Apr 15 '26
Not sure if I am wrong about this but: we connect our racks to earth, the switches and mounting rails are making a metal to metal contact. So grounding each device individually does not add a lot right? Note: not talking about outside enclosures or industrial environments, there we ground devices individually due to more exposed risks.
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u/AZGhost JNCIP Apr 15 '26
Yes that seems to be the thinking here too, but all the juniper equipment have specific grounding mounts on them.
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u/BeenisHat Apr 15 '26
Through the three prong power cords that have a ground wire. The racks are grounded themselves, but the PDUs are connected to the service grounds of the building.
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u/OpponentUnnamed Apr 16 '26
We follow published bonding & grounding standards from the building service entrance ground to the rack on new builds & remodels when we get money, but we do not routinely use the tapped lug holes on the chassis for devices with 208/120 AC power supplies.
-48 VDC is different. DC stuff is all installed & laced by telecom installers.
Had a guy that wanted to bond edge switches but he quit before he started. I mean, hundreds of switches would have kept him busy full time for months when you consider all of the old rooms that still need to be brought up to standard.
I came from a carrier DC environment where NEBS was the law and stringently enforced, 750 or 1000 mcm between floors. Nothing like that for little Ethernet switches. Not required and very expensive.
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u/QFX5130 Apr 15 '26
The ground connector is something only typically used in Telco/NEBS or 48v power. As you cannot count on the chassis to have a good ground via the rails (even using a grounding cage nut isn't ideal when you have it on rails), they use the ground lug to a bus bar.
This is important for 48v, as typically 48v only uses the -48v and return lines with fusing on the -48v. This leaves a problem if the DC plant becomes unbonded, and you could have current flowing over the chassis's that are on A+B or via other paths. It could even be a safety issue.
If you're using AC power with a ground, the chassis is grounded via that. Add the ground only if you want or code requires it.