Ask the Expert Question-and-Answer Archive

by Ron Joseph

October, 2004

Intumescent Paint

Q. We are changing the power in the building from 240 volt to 480 volt. The existing wire and conduits will handle the current change but the conduits have to be in a one hour fire rated enclosure. Can we paint the conduits with an intumescent paint to acheive this rating. The project is in New York City. Thanks

Thank you for your e-mail. In principle, you can paint the conduit with an intumescent coating but you might need to experiment with a corrosion resistant primer followed by the intumescent topcoated. These coatings are usually applied at a fairly thick film thickness and you might want to ensure that if the conduit flexes the coating does not crack or flake off.

With regard to achieving a one hour fire rating you will need to get a certification from the coating manufacturer that demonstrates that the products will perform as required provided that the film thickness is achieved.

Several companies sell intumescent coatings and you may want to shop around on the Internet.

Best wishes,

Ron Joseph