EBME Forums Forums Maintenance Technical Assistance Electrically Conductive Grease

We are having problems with earth bonding tests on diagnostic microscope which have various aluminium swivel joints.

Unless I can overcome this problem, I will condemn these scopes.

Have any of you used this kind of grease on close fit joints to try and overcome the problem of oxidisation on aluminium?

Cheers

Mark

Mark,

I have never come across conductive grease being used for safety/grounding purposes. I am not sure I would trust it for maintaining an earth path.

How feasible would it be to run an earth braid from the base of the microscope (which I assume is grounded)to the rest of the Microscope?

Best wishes,

Paul

Paul,

The grease idea was a 'stab in the dark'.

I presume that the aluminium has been anodised so that it's hard-wearing. Does anodising cause higher electrical resistance?

I've thought about adding additional cross-bonding, but this would look a mess(too much isolated exposed metal). Plus, would that not be a modification?

I think that I'll be happier if they're condemned.

Cheers

Mark

If you are insisting on condemning that microscope, Mark (and earth bonding is the answer), don't forget the well-known charity group based just twelve miles from where you are (Adrian knows the lady concerned) ... and I happen to be there right at this moment!

Geoff,

Let's just say that I'm a bit involved with this one for the time being.

This particular problem is not an isolated one, so I would urge anyone else who has one to check it's earth bonding from head to toe.

Cheers

Mark

Mark

I would tend to go for a bonding strap as Paul suggested.

If you put any form of grease on those swivel joints, I suspect you would then be able to lock / orientate them in the desired position.

Bonding is the only option as sttated above.

If the aluminium components have been anodised, would they still be classed as 'exposed metal'?

Cheers

Mark

Semantics, Mate. If the protective earth reading is too high, simply add earthing "straps" (green and yellow "pigtails") until the value is brought back within limits. What's the problem? Kit like this has been around since the Dawn of Biomed (without, as far as I recall, anyone having sparks jumping out of their ears)!

In the good old days I can remember seeing earthing braid on slit lamps for the same problem.

I've also tested units where the only exposed metal is anodised and you can only get a contact by "stabbing" through that coating.

Lee