Are silicone BNC covers an ESD hazard? - Page 1
Forum section: electronics / general

author: neverendingstudent
author_rank: Regular Contributor
timestamp: March 09, 2025, 09:39:06 pm
content: Hi everyone. I recent bought some silicone dust caps for the BNC connectors of some of my bench equipment (and maybe to leave on storage items as well) and I just had the thought...Are these an ESD hazard? They are standard silicone, not made to be ESD dissipative, so they'll be an electrical insulator. Should I be concerned about this or it is a non-issue?For reference, this is the product I bought:https://www.amazon.com/dp/B0D2JBXBTVThanks everyone.

author: coppercone2
author_rank: Super Contributor
timestamp: March 10, 2025, 03:25:56 am
content: Ok basically if you look at a manual for alot of equipment that has BNC connectors on it and its not rated for many hundreds of volts like an oscilloscope it says wear esd protection while handling, meaning, just because the cover is grounded, you don't want to zap the energy into the BNC connector.The shield of a coaxial cable is a capacitor with the wire in the cable. When you zap it, energy will go into the center conductor. So yes, I think you should have ESD safe bootsI think it usually happens when you touch the shield of a big long high impedance cable. But there is cables and capacitance in the instrument.And the boot is like stretched and stuff, so that makes it more active I think. Proper BNC cap's DO have a bit of rubber in there, which might be ESD safe, but those are sold by RF companies so you would imagine they would figure out that its breaking equipment if it was doing that, but who knows, maybe there is a few fried amplifiers in the world that broke from such a little oversight.So I think1) for zapping JUST the front panel connector, its probobly hard to fry2) touching the shield on the other end of the long cable connected to test equipment could possibly damage something3) touching center conductor is worstAnd my opinion is : you spent k$'s on test equipment, don't cheap out to buy mcmaster silicone bolt cap's for your VNAhttps://www.mouser.com/ProductDetail/Amphenol-RF/202100?qs=%252Bm72Q7GxMuytdGxO6sjc3w%3D%3D&mgh=1&gQT=1And its also a lab functionality issue. Yanking condoms off my test equipment? thats some BSAnd that cheap shit might foul up and leave residue on your connector that you need to clean off or get super stuck (which can damage the connector if you try to pull it off with pliers or something). Silicone might be better but u never know what kinda additive or whatever they might use. Imagine it ends up releasing corrosive shit in 5 years because of some bad batch or w/e?And at work, you will see, everything is considered a ESD hazard. All your tools are like ESD safe. It will be part of like lab procedures. sometimes its a pain in the ass to find ESD safe tools you want for work because of this blanket requirement, but its like the professional standard.

author: joeqsmith
author_rank: Super Contributor
timestamp: March 10, 2025, 04:14:19 am
content: I've had some of my wifi gear shipped with similar caps on the SMAs. Also a lot of the low cost RF bits have came with them as well. I've bought some RF cables that also used them.I have no idea about the material makeup but some you can smell outgassing. Caplugs makes some that are static dissipative.You can also buy low cost ones similar to Amp ones linked above. I would not recommend the shorting plugs but the others I bought appear to be decent quality. They offer them with and without the chain.https://www.eevblog.com/forum/testgear/bnc-protector-caps/

author: fourfathom
author_rank: Super Contributor
timestamp: March 10, 2025, 05:37:30 am
content: I don't see why the protection caps (covers) would be any more of an ESD problem than not having covers at all. I sell and ship various RF products that use SMA jack connectors, and I put plastic caps on the jacks. I do it to protect the SMA jack threads and to keep dirt/lint out of the connector.