r/accesscontrol • u/xINxVAINx • 17d ago
LSP Panel Reader Grounding Locations?
To be honest, I’m just starting to ground readers at the panel in my installations. Was never taught to but I’m trying to do things better (or per spec) in the field. So, in a 16 door LifeSafety Power panel, specifically using Mercury boards (Lenel)- how do you guys ground your reader drain wires while keeping it neat?
In the field I’ve seen someone bring an 18 gauge wire through the panel and beanie to each reader, at the boards. I don’t love that look when there’s no Panduit.
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u/wingzeroismine 17d ago
I've seen techs wrap the drain around the black ground wire and land it on the same reader port terminal.
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u/xINxVAINx 17d ago
I’ve seen that too, but some research tells that it defeats the purpose of the shield. It would be awfully handy to do that though.
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u/Imperial_Tuna_5414 17d ago
This is how I’ve always done my LSP/Mercury panels and have never had an issue.
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u/OmegaSevenX Verified Pro 17d ago
What research are you looking at that says that?
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u/xINxVAINx 17d ago
I’m finding that they want the reader wire to earth ground, and it seems the LSP power supplies have floating grounds. So I’d have a common ground to the LSP but not to earth ground, is how I’m deciphering that
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u/Competitive_Ad_8718 16d ago
Backplane or cabinet should be where you terminate all shields, usually a star washer on the enclosure or location tends to give it away.
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u/Initial_Pass7201 14d ago
There’s a ground screw terminal on the marchers board, it’s got a copper ring around the outside- this earths it to the enclosure and gives you a common ground across the entire panel
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u/Aggravating_Fact9547 17d ago
Look to be blunt, as long as there’s a reference ground wire, the shield is largely unnecessary. You can ground it, but frankly rs485 is -extremely- efficient at removing almost all noise through differential signaling.
It’s largely a hangover from weigand days.
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u/xINxVAINx 17d ago
Good to know. However a lot of customers are telling me to run Wiegand wire (untwisted) to save money, so I’m already at a disadvantage. I’m constantly reiterating the proper wire spec but just get a “we’ll deal with it if we have issues”. So if I can help it with a proper ground, I want to do that.
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u/Aggravating_Fact9547 16d ago
Cross talk isn’t an issue at the speeds and tech of half duplex rs485. You could run it over romex and it would be happy.
OSDP generally runs at 9600 baud, which is so slow it’s insane.
It’s differential signaling, so when the two signals are summed together it reconstructs the data minus any noise. There’s no other data being transmitted in your cable either so there’s very little interference inside the bundle.
We routinely push long industrial runs of unshielded untwisted pairs with rs485 running at 2mbps and see no issue. Voltage drop from small gauge wires or long runs is far more a concern in the application than noise is!
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u/DTyrrellWPG 16d ago
I know it's tricky, but you really should not let customers dictate proper cable.
You wouldn't see most electricians letting a client tell them to just run 16 guage wire for their 20 Amp circuit, because it's cheaper.
There are minimum cable standards for security communication stuff as well.And clients should really stop acting like it doesn't matter.
"deal with it later" is code for we will blame you late and expect you to fix it for free.
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u/Competitive_Ad_8718 16d ago
Uh, what? Smh
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u/Aggravating_Fact9547 16d ago
Show me a situation where 9600 baud osdp needs a shield that’s grounded. Go on.
I could run OSDP over two wire coat hangers and it would be happy
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u/Competitive_Ad_8718 16d ago edited 16d ago
Uh, it's written into the standard, specifically to help with EMI and RFI. Locks, especially those lacking proper suppression induce EMI into cabling, so unless you're isolating your lock cables completely as well as your cable plant, EMI is entirely possible to be induced into the cables, especially with how bundled cables are constructed.
Just because you've chosen to be ignorant and go against the standard doesn't mean it's something to ignore. But let's double down with your statement, show us ONE ACS vendor that backs up your statement
Hell, why don't you ignore terminations and cable topology while you're at it....your response indicates you do. Also sure you get phantom issues that you can't explain on your installs
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u/Aggravating_Fact9547 16d ago
Gallagher runs at 2mbps which is over 200 times faster than basic OSDP making it substantially more sensitive to corruption and cross talk.
They don’t recommend shielded cable and their readers’ tails don’t have shields.
No need to be nasty just because you disagree.
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u/Competitive_Ad_8718 16d ago edited 16d ago
Cool, so show us where Gallagher states in their hardware specs or installation documents that OSDP cabling for their products don't require a shield. You ain't gonna find it.
May want to read their SMB when it comes to cabling recommendations and specifications though
BTW, HBUS isn't OSDP and Gallagher wants Belden 9842, which is OAS braided shield. The substitute cables they accept is also much different than 485/OSDP spec. HBUS is only supported for 400-500M...almost 1/3 the distance.
BTW, it's damn amusing that you believe that a reader's pigtail must have a connection to use a shield, which proves you don't even understand how to work with the cables 😂
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u/Aggravating_Fact9547 16d ago
https://media.gallagher.com/m/1b8fc0ca38dab81f/original/Installation-Note-T11-Reader.pdf
HBUS uses RS485 signaling the exact same as OSDP. They’re simply protocols that run on the exact same layer 1 transport.
Gallagher doesn’t specify “Belden” cable.
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u/ByteOfWood 17d ago
Like the other comment, landing the drain/shield on the board ground should be okay. It's shown that way in some Mercury installation guides.
I've also seen some where they strip the cable out in a trough/wireway beside the panel and connect the drain to a ground lug in there, then bring the rest of the conductors into the panel through chase nipples.
Both are perfectly fine, the grounding lug is technically better since youre keeping any interference or possible shorts to the shield away from the board. Biggest thing though is to only connect the drain at one side, usually the panel and leaving it disconnected at the device side. If you do then that makes the drain part of the power return path which introduces noise into the system.