I have to power now one monitor power supply and mainboard on my work desk and want to be sure the wood is good insulator.

thanks

 

A wooden bench is an excellent work surface. A good enough insulator, but doesn't tend to allow a build-up of static.

Resistivity is between 10^14Ωm and 10^16Ωm when oven dried, but possibly as low as 10^3Ωm if damp which is why it cannot be considered an insulator for the purposes of standards compliance.

 

For what kind of voltage? Remember, wet or dirty wood is not an insulator.

 

I used to think cement didn't conduct. Then I saw a video. Four men died when their scaffolding contacted some high voltage lines. The scaffolding was on rubber wheels and they became conductors to ground. @DickCappels is right - what kind fo voltage?

 

Pressure-treated lumber is surprisingly conductive (especially as the humidity increases, dry maple is a pretty good insulator right out of the oven.
Your best and safest practice would be to put some long screws through the mounting holes, tighten them down with some small nuts to make some stilts to keep the board off of the bench. Also, keep all cords on your bench so the open line-voltage circuitboard doesn't get pulled off the bench by the weight of the cables.

 

If concerned, obtain a required size of Formica laminate from HD etc.

 

Chipboard (or particle-board as it is called in certain places) absorbs water like a sponge. Tree wood (for want of a better term) is much less of a problem. I work with 230V circuit boards on an oak desk, and have never notice any conductivity.
I suppose it could be measured - take two pieces of aluminium foil, attach to desktop, connect one to live and measure the current between the other and earth. <700uA and you're OK as it is as safe as any domestic electrical equipment.

 

Is your desk top varnished or lacquered? Remember that magnet wire only has a covering of that type thing for it's insulation, so you should be good if the desk is finished in that way.