Tip of the day.

[Helge A. Bentsen]

Do not, as one of my customers discovered the hard way, seal cable connections through walls with expanding spray foam insulation.

He called me today complaining that he lost his delay speakers on saturday. I inspected his installation today, now he's lost 6 out of 8 lines in his return multicore, all of them were functional on friday the day his boss sealed the hole in the wall......

 

[Bennett Prescott]

Oh, wow! That sucks... Interesting that the foam likes cable jackets so much.

 

[Ryan Lantzy]

I'm not sure it's a matter of like vs. exothermic chemical reaction. I'm pretty sure that expanding foam stuff get's pretty hot (especially on the inside) when first sprayed.

 

[Helge A. Bentsen]

Re: Tip of the day.

Me thinks pressure from the expanding foan has squeezed the cable against a sharp edge inside the wall. Speaker cables and power lines are still intact. Still....

 

[Ryan Lantzy]

Re: Tip of the day.

Me thinks pressure from the expanding foan has squeezed the cable against a sharp edge inside the wall. Speaker cables and power lines are still intact. Still....

Possible but...

"Two part froth foams will generate a skin (surface of raw foam) temperatures of 70 F to 122 F from 0 seconds to 120 seconds from initiation of mixing. Core temperatures (from the approximate center) will be 125 F to 265 F from 60 seconds to 300 seconds from initiation of mixing."

You'd likely be dealing with a "core" temperature here if the cable and foam were in a hole because it would be unable to vent the heat to the surrounding air.

Could be a mixture of both... heat to soften the insulation, pressure to squeeze it and pinch the wires together.

 

[John Roberts]

Re: Tip of the day.

a vom will tell if you're dealing with shorts or open... not that it matters which.

JR

 

[Marsellus Fariss]

Re: Tip of the day.

Don't get that stuff on your skin either like I did once when I was young. Painful to scrub off once it dries. Never experienced heat though.