ECN Forum Forums Safety Discussion and News Occupational Safety Discussion Appliance Paint

Not necessarily about Occupational Safety, but I have this question that I'm dying to know the answer to.
OK, can the paint on a Metal bodied Appliance, be considered as Insulation, in the Electrical sense of the term?.
As a rule this paint is a baked on enamel, if my memory serves me correctly.
Enamel is also used on the wire that motors are wound with and they carry Mains Voltage.
So, could you say that a layer of this paint on a Washing Machine or a Refrigerator, would be thick enough to prevent an electric shock, should the metal body underneath the paint become live?.
I realise that the layer is very thin, but aren't we also told to remove the paint around Grounding terminals, because it prevents a proper connection.
I don't want to make a big deal out of this, I was just wondering what your take on this would be?.

Cheers,
Mike :}

 
That’s a good question, Mike. My best guess is that no appliance manufacturer or paint producer would [on paper] claim that the coating was considered ‘insulating,’ except in very special circumstances, and probably not on a surface accessible by the public or unqualified individuals.

Simple question: Is the paint UL listed as insulation?
It may, in fact, provide a degree of additional protection but it can not be relied on for that purpose without a listing.
The varnish used on motor windings is an integral component of a listed assembly so that doesn't count.

Thanks for your comments Bjarney and Big Jim, I was just trying to float an idea.
(As silly as it is!)
I'm not sure about the listing of paint or any other coating for that matter, by UL.

Years ago I had a motorcycle. It was old and rusted. I took it apart and repainted it. Put all the wires back and nothing worked. Turns out I painted the ground wire and had to scrape the paint off.

Some inpectors here will red tag you if the ground to the building steel is painted. Got to get out the grinder and get the paint off.

Short answer, paint is an insulator.

Long answer, it is not acceptable as an insulator for insulation purposes.

sorry, wrong button

[This message has been edited by GA76Apprentice (edited 12-12-2004).]

AN answer to the question of enamel being an effective insulator is "no". Technically it is, yes, but I promise you you can get a shock off a painted machine!

In order to secure a good electrical earth it is necessary to remove paint from the metal in question; but this is just to ensure the best possible connection.

If paint in general is not an insulator, how about Glyptal(R)? I still have a couple of quarts of good ol' 1209 Black- great stuff!

If Glyptal does not have a specific UL listing, it is not approved as an insulator. I beleive it is commonly used in the manufacture and assembly of listed devices (motors and trandformers) but that happens under specific and controlled conditions not usually found in the field. If you check it with a megger, yes, it has the physical properties of an insulator but it is not approved for general use as such.

Powder coating is a great insulator - though not one I'd want to trust my life on entirely. I've done 1000 VAC hipot tests on powder coated aluminum chassis (what's plural for chassis? Chassiseses? Chassi?) where I've clipped the two "aligator clips" directly onto the piece of metal (covered by the powder coat), and had no current flow at 1KV. Thats with the teeth of the clips trying to dig into the paint - amazing stuff. If I were a heavy equipment operator, I'd want every surface I might contact to be coated with the stuff...just in case I'm digging in the wrong spot.

The UL standards I work with (in telecom) do not consider enamel wire to be real insulation when it is being used for a safety function in an AC mains circuit. Enamel can be used, with no other tape insulation, for transformers requiring only functional insulation in applications that have no safety requirement for any insulation at all (such as ethernet transformers), or for basic insulation in telecom circuits, provided each part manufactured is hipot tested (and a few other minor requiremnts are met).