ESD knowledge?

[tbourner]

Anyone know about ESD stuff? I'm trying to set up our EPA in our new lab and have a problem with 1 bench.

 

I've got the ESD wrist strap plug point to screw to the front of the bench, which is reading just under 1M to the eye, then a yellow ESD lead which reads just over 1M from one eye to the other (about 1.5m long).

I held the 2 together and measured from the wrist strap point to the grounding point on the wall which I'd bolted the yellow cable to - just over 2M, which is correct.

BUT, as soon as I put both the eyes (which I was holding together) onto the same bolt (bolt is rivetted to the ESD mat on the bench top, and protrudes under the bench) and put a nut on it to hold them in place, the reading from wrist strap point to the grounding point goes up to 17M!!!!

 

So the way I see it, the voltage from my DVM is choosing to go down one wire, up the bolt, around the bench top a couple of times, down the same bolt and along the other wire to the ground point!!! WTF!!!!

[Rob]

Wtf? AFAIK your post is full of acronyms FWIW, like OMG acronyms FTL.

[tbourner]

Only ESD and EPA, which mean Electro Static Discharge and Electrostatic Protected Area respectively.

The M is a Megaohm, but I couldn't be bothered to find the symbol.

[Rob]

I thought you meant a 2metre cable. I presume a "bench" is some sort of horizontal table-like workpod?

I think I should leave this thread now, I don't think I can help.

[Thorin]

MFI CIS FBI MI5 perhaps?

[JustGav]

Is your grounding point on an earthed ground or on a clean ground system, remember if it is on a clean ground system it could go though some spark arrestors which would explain why you are seeing such a high resistance (simple air gaps)

[tbourner]

No idea, they're just ground points on the truncing on the walls. Same truncing as the twin sockets come from so I'm guessing it's mains ground.