Q. My questions have to do with existing ungrounded circuits in older homes. My understanding is that you should always replace worn-out two-slot receptacles with new two-slot receptacles (although they’re not always easy to find). However, I’ve also been told that in some locales you can install a three-prong receptacle in an ungrounded circuit as long as you fill the ground slot with epoxy. This is presumably to prevent someone from using a grounded appliance on the ungrounded circuit. What’s the code requirement, and what about this epoxy business?

A.Redwood Kardon responds: In my jurisdiction (Oakland, Calif.), two-slot receptacles are readily available and must be maintained on existing ungrounded receptacles, unless the outlet is upgraded with a ground per the NEC. The "epoxy business" sounds funky to me. It is not an acceptable practice where I work, and there is certainly no such "fix" in the NEC. This issue most often surfaces when someone wants to install a dedicated computer outlet. In that case, a separate ground may be run, as noted above, and a three-prong outlet installed.

Redwood Kardon is a code official in Oakland, Calif. For more code-related information, visit his Web page at www.CodeCheck.com.