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#38001 05/13/04 08:38 AM
Joined: Feb 2003
Posts: 24
Has anyone had a problem with their electrical equipment or mounting screws deteriorating after time from the chemicals in the wood?
There are a few juridictions around Michigan that state we need some sort of spacer between the equipment and the wood, and use stainless steel screws.
Is there a code or UL listing out there on this?

#38002 05/13/04 10:26 AM
Joined: Mar 2001
Posts: 333
Doug, here is a link to Simpson, regarding corrosion with the new wood treatments.

#38003 05/13/04 03:47 PM
Joined: Nov 2002
Posts: 12
The problem is the copper used to treat the wood causes galvanic corrosion in dissimilar metals.

Ranked by similarity:

Austenitic Stainless (passive i.e. with protective film)
Chromium Steels (11-30% Cr) (passive)
Inconel (80% Ni, 13% Cr, 6.5% Fe)
Nickel and High Nickel Alloys
Monel (67% Ni, 30% Cu)
Bronze, Gunmetal
Alpha Brass (70% Cu, 30% Zn)
Naval Brass (60% Cu, 40% Zn)
Austenitic Stainless (active i.e. protective film removed)
High Nickel Cast Iron
Chromium Steels (active)
Cast Iron
Mild Steel
Aluminium Alloys


Note copper and zinc ("galvanized" or "plated") are quite far apart on the table.

I'm pretty sure the newer wood treatment (which is rusty in colour) contains no copper.

#38004 05/14/04 01:42 AM
Joined: Mar 2001
Posts: 333
You can't go by the color of the wood. It can still be green and be treated with a newer preservative.

#38005 05/14/04 03:31 AM
Joined: Nov 2002
Posts: 12
You're right. And moreover - according to StrongTie - most of the newer treatments do contain copper.

Their advice basically comes down to using heavy duty zinc fasteners and fixtures, which will react just as much with the copper as lighter coatings, but take longer to show it.

But we're interested in enclosures not coated structural brackets sold by StrongTie. A plastic box secured with SS screws will do.

#38006 05/14/04 03:39 AM
Joined: Jul 2002
Posts: 8,443
Likes: 3
Doug S,
I come from New Zealand and Tanalised (treated) Timber for house construction was banned for use, back in the 1990's.
For the simple reason, it kills Fire-fighters that extinguish houses, made of this material.
As Kobuchi posted above, there are a lot of nasty chemicals in that timber, which only release when the timber catches fire and burns.
I'm not talking about Inhalation of the smoke, it's caused by penetration through the small areas of exposed skin that a FF has in a fire.
I hate the stuff!. [Linked Image]

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