Im dumb, tell me what to do with my ESD grounding mat

[Mp3]

I have a big velleman ESD mat.

• I don't have any exposed copper wiring, the radiators and any exposed piping are painted over (building hundreds of year old), best guess is an old metal intercom box
• It came with one alligator clip that snaps to the pad, and it has multiple points to snap something to.
• I have some grounding wrist straps.

Ok now please help me decide what to do with it?

• Put a wire between the metal frame and metal screw of the intercom box built into the wall, which might not be connected to anything anymore on the other side of the wall, and connect that to one of the grounding points on the mat
• Get an extension cable and connect the mats grounding point to the AC ground prong.
• Connect the ground on the mat to the device i'm working on and one of the above

Let's not discuss the degrees of ESD protection but please help me decide how to best use the pad i have. I read a lot on Google and youtube but there seems to be no definitive answer.

[MosherIV]

Hi

  2. Get an extension cable and connect the mats grounding point to the AC ground prong.

Check the resistance between one of the metal studs on the mat and earth is around 1M
Just put your work on the mat.
Connect wrist strap to the mat and wear it.

[james_s]

Get a grounded plug, connect the wire from the mat to the ground screw in the plug, plug it into the wall.

[Mp3]

I have done this and i get 1M  resistance but i also get about 1.5-2 volts AC power across the metal studs on the mat.
is this safe to work on? that seems worrying
Thanks in advance.

[MosherIV]

When you touch the mat, do you get that tinggley feeling?

If so, something is wrong.
If not everything is fine.

[Electro Detective]

I have done this and i get 1M  resistance but i also get about 1.5-2 volts AC power across the metal studs on the mat.
is this safe to work on? that seems worrying
Thanks in advance.

I would use any affordable multimeter that has the Low-Z function to confirm whether it's merely a stray 'ghost' voltage
..or  -old wiring-  issues waiting to bite   

FWIW, any direct 'continuous' connection to the mains ground/earth wire which is usually bonded to the Live Neutral at the switchboard, is waiting for trouble...
especially in an older property which may have dodgy 'compliance' work done with a mix of shared earths and neutrals to fool the electrical inspector 

i.e. make sure the ESD routine works as it should or lose it to avoid the possibility of 'can't happen' zaps   

[Mp3]

I have done this and i get 1M  resistance but i also get about 1.5-2 volts AC power across the metal studs on the mat.
is this safe to work on? that seems worrying
Thanks in advance.

I would use any affordable multimeter that has the Low-Z function to confirm whether it's merely a stray 'ghost' voltage
..or  -old wiring-  issues waiting to bite   

FWIW, any direct 'continuous' connection to the mains ground/earth wire which is usually bonded to the Live Neutral at the switchboard, is waiting for trouble...
especially in an older property which may have dodgy 'compliance' work done with a mix of shared earths and neutrals to fool the electrical inspector 

i.e. make sure the ESD routine works as it should or lose it to avoid the possibility of 'can't happen' zaps   

No tingley feeling, but i live in a very old building with bad wiring, all running off a 60 amp breaker  so maybe i will search harder for somewhere to mount a grounding screw...