What does soot over an eletric TPR valve indicate

[ren ramsey]

What does the soot marks over the TPR valve on the electric water heater indicate?http://i333.photobucket.com/albums/m378/ramdino/IMG_0822.jpg (http://s333.photobucket.com/user/ramdino/media/IMG_0822.jpg.html)

[Rick Cantrell]

Not likely to be soot. Most likely just dust, coming through the TPR opening.
If it is soot, it may of had (or has) an electrical problem.

[Jim Luttrall]

It could be candle soot deposited just like on studs show on an outside wall (Brownian effect). The area above the TPR valve will be warmer than the surrounding shell causing air movement and dust and soot will deposit as the air moves.
BSD-150: Black Stains on Carpets and Ghosting of Framing ? Building Science Information (http://www.buildingscience.com/documents/digests/bsd-150-black-stains-on-carpets-and-ghosting-of-framing?topic=doctypes/digests)

[Kenneth Clayton]

I have seen this soot plume before. I asked the seller if he had problems with the tank, and he said "it went out last year and I replaced the burned out heating element."

[Scott Patterson]

This is a tell-tail sign that the element has burned out and most likely if you open the access cover you will find burned contacts on the heating element, or it was replaced....

When I see this I always take the access cover off the take to look at the heating element.

[Rick Cantrell]

Guys
A burned out element (which is inside of the tank) would not leave soot on the outside of the tank.
Could disposable be a lose connection at the element (or elsewhere), although doubtful.
I have several rental properties. Have had tenant call me about this same SOOT.
Go out and find that everything is working fine.
It's dust deposited by convection, (I've not seen any other cause).