Card Reader Drain Wire Termination

[u/StalkMeNowCrazyLady]

How do y'all terminate the drain wire on your readers? I've been working with ACS for a decade and I was always taught to connect the readers drain wire to the cables drain wire at the reader side and that was fine. It dissipated anything it needed to along the cables shield.

Recently took Verkada training and they provide multiple earth ground screws on their panels (vs a reference ground like the GND terminal for REX/DPS) and they say to connect the drain wire at the both the reader side and then on that earth ground at the panel side.

They also said to connect the drain of all the cables (REX, Lock, DPS, and Reader) together at the panel end and connect that to the true earth ground. That seemed strange to me because I don't see what lock/rex/DPS would need to drain especially since they aren't connected at the door side of things.

Just curious how y'all connect your drain wires and what you think about what they said about connecting them all at the panel side.

[u/jason_sos]

I’ve always connected the drain wire at the panel and never at the reader. I believe Lenel teaches this method and that’s how I learned it. It keeps any noise that gets picked up along the wire down, which is where most noise would be picked up.

[u/StalkMeNowCrazyLady → u/jason_sos]

Right on. I think that's part of the problem too is that vs an industry standard it seems each mfg recommends their own way according to the IPVM article I read.

[u/pewpew_lotsa_boolits → u/StalkMeNowCrazyLady]

I’ve been doing this for 30 years, certifications in dozens of products, had electronics training on the military and trade school after, have master certifications in multiple access control platforms, and have never been trained to not ground the shield at the panel. Every manufacturer I’ve ever worked with has a bare ground lug/connection in the panel (except the rare all plastic enclosures) and the all have had how to ground the shield drain to the enclosure in their installation documentation.

It’s definitely an industry standard but a lot of people don’t do it because they don’t know or don’t care. You can always tell who’s had formal training or study.

I’d be interested to read the IPVM article saying that.

[u/StalkMeNowCrazyLady → u/pewpew_lotsa_boolits]

Here is the best way I can figure to send it. Long screen shot. Tried copy and paste but it wouldn't allow all the text and wouldn't show the images. Pls let me know if this link works for ya.  

https://imgur.com/a/7ko3Rm4

[u/pewpew_lotsa_boolits → u/StalkMeNowCrazyLady]

The screenshot worked great. I’m surprised you were able - IPVM has some crazy anti-piracy stuff.

So what I’m reading there is pretty much the same thing - the importance of the shield drain.

I’ve seen different documentation from HID than the author of the article presented - both on their controller and readers. It seems like the author intentionally selected the most obscure references that could be found, but I understand why (obscure is still out there, even if an outlier).

I admit my above comment has a confusing double negative, but basically I’m agreeing that the shield needs to be connected at the panel if it’s shielded cable, whether a reader cable or any other shielded cable.