Gray(Dapo),
That rule about the depth of the signal strip is about the only electrical regulation that I've ever thumbed my nose at.
If I'm burying a cable or some conduit, the strip goes at half the depth of the trench, no questions.
One other thing, ever noticed how when a digger bucket catches a signal strip, it stretches the plastic (as it is supposed to do) and ends up pulling a significant length of it out of the dirt, before it snaps.
I often wonder how many people actually bother to replace the bit that's been pulled out of the ground, further along the trench from where they are digging?.
Makes the next dig in that area fun with no strip in the ground. [Linked Image]

{Edit: BTW watch the edges on that MagSlab stuff, they are bloody sharp, one guy at work managed to cut open a cowhide glove he was wearing while installing some.
I'd hate to think what would have resulted if he hadn't been wearing work gloves!} [Linked Image]

[This message has been edited by Trumpy (edited 03-25-2006).]