I’ve noticed the static mats in the electronics room aren’t tied to ground like they should be but are electrically floating. Any reason why?
Glad you asked. You are welcome to bring your own wrist strap and grounding snap. Plus each setup has it’s own instructions which is your responsibility to follow.
If we ground them, then DMS is liable for what uninformed users do. Like disassembling tube radios with hot a chassis placing them on the mat and making the whole bench LIVE!
Not meant as an attack on you but we are more concerned with people getting zapped instead of chips.
2 Likes
Fair enough. I agree safety should be a top priority though I’m pretty sure the mats can be grounded safely. I’m no expert on it though since it was always taken care of by someone else at the places I’ve worked. My understanding is the mats were tied to AC ground through a 1M resistor and the top surfaces of the mats have a fairly high resistance as well. So placing a live chassis on the mat doesn’t make the whole mat live in a dangerous way. I’ll have to look into it though.
In certain high voltage situations that is not industry practice. Lampy is correct, and I’ve actually seen areas in assembly plants where there is an island in the static dissipative flooring for HV work.
1 Like
Aren’t some of those benches dissipative though? Or do they just look like it?
Ok, my past experience has not been with with high voltages so I’ll concede the point. Yes the surfaces are static dissipative but what I was really running into was picking up large amounts of 60 Hz noise while working with millivolt level signals. Connecting the static mat to ground helped considerably. Which made me wonder why they weren’t grounded the way I was used to. The HV concerns explain it. Thanks.
Hey, so thinking about this a little, you should not do work on a dissipative surface at all in that situation, since the HV can arc right through the resistive material right into the metal foil backing.
Really the idea is to keep an unwitting tech from completing the circuit, and I’m not sure that leaving the benches ungrounded helps with that.
Grounding might actually improve the safety in that situation, since you’ll just arc out to the table causing a lot of noise and smells and blown fuses… but that is obviously not an ideal situation.
Opinions only, curious what others with more experience working on HV systems and also anti-static equipment.
I had that thought as well but again don’t really work with high voltages so couldn’t say.
We can debate the merits of grounding/not grounding under several situations. But it is still up to you to ground the station per YOUR needs at the time.
If you like I can purchase new straps as I tossed the old rotting ones.
We would need at least one more mat as well.
3 Likes
Understood. At this point for me at least it’s just a discussion so I can learn more since grounding is a subject that is easy to get wrong (me not thinking about HV use for instance).
I’m fine with bringing my own wrist strap but all I saw were the under desk wrist strap ground points. I didn’t see any of the snap on connectors to connect the wrist strap to the mat or the mat to ground if needed. I resorted to alligator clips but that’s sketchy.
I don’t think that’s a bad solution. Maybe we should post some signage letting people know what the configuration is? I don’t usually go in assuming that the last person knew anything about setting up the bench properly anyway 
*that’s not a dig on anybody specific, but how many times have you come in and seen a soldering iron set to 850F? 
1 Like
How about on at 850F all weekend! Come on people, treat your space better or you may lose it.
All I end up doing as Chairman is to spend 2-3 hours cleaning up others crap! And finding where our tools went. If you want better we all need to help out keeping the space clean and functional.
1 Like
That person is a danger to themselves, to the people who were at DMS over the weekend, and DMS itself.
I hate to suggest Junior High Justice but it seems appropriate. When I was in Junior High, if a student did something wrong, the teacher would take the tool away from everyone until the person responsible was identified (which always involved the culprit admitting they made a mistake). The punishment was cleaning duties for an arbitrary time.