Wiring through joists w/ Hot Air Ducts

[volts500]

Short sections of EMT, as applied in this case, are not required to be bonded. If one is really concerned about bonding the EMT, then extend one end of the EMT to a metal box mounted on the next joist, run the cable into the box and ground the EMT and the box with the Romex equipment ground wire. While a conduit isn't required in the first place in this case, it makes for a better installation because the EMT would not allow toxic fumes from the Romex cable to enter the cold air return duct......a PVC conduit would just add to it.

electrician

[phil-news-nospam]

What about a ceramic conduit? They used to make those a long time ago. It was called K&T. So we can just adapt the tubes to be larger, hold a whole cable instead of one wire, and run through a duct instead a single joist. Maybe glass (not fiberglass) would also work.

[Chris Lewis]

Have you ever tried to stretch ceramic conduit? ;-)

I suspect you'd get into trouble with this practise, because the thermal insulation value can be quite high. K&T materials simply aren't approved anymore.

[phil-news-nospam]

| According to : |> In sci.engr.electrical.compliance volts500 wrote: | |> What about a ceramic conduit? They used to make those a long time ago. |> It was called K&T. So we can just adapt the tubes to be larger, hold a |> whole cable instead of one wire, and run through a duct instead a single |> joist. Maybe glass (not fiberglass) would also work. | | Have you ever tried to stretch ceramic conduit? ;-) | | I suspect you'd get into trouble with this practise, because the thermal | insulation value can be quite high. K&T materials simply aren't approved | anymore.

Why would it need to be stretched? You just drill a hole in each joist that is the wall of the duct, and slip the conduit across from one to the other, and fasten it in place so it can't slip out. Now you have a path through the ductway that is isolated from the duct itself.

This is not a long path. Select a tube wide enough to allow air to flow through it (between the two ends, not into the duct) with the cable to be used.

[Chris Lewis]

I was referring to the "just adapt the tubes to be larger" remark. If there ain't one stock, you'd have to make the tube yourself. That seems a bit overkill ;-)

[phil-news-nospam]

In sci.engr.electrical.compliance Chris Lewis wrote: | According to : |> In sci.engr.electrical.compliance Chris Lewis wrote: | |> | According to : |> |> In sci.engr.electrical.compliance volts500 wrote: | |> |> What about a ceramic conduit? They used to make those a long time ago. |> |> It was called K&T. So we can just adapt the tubes to be larger, hold a |> |> whole cable instead of one wire, and run through a duct instead a single |> |> joist. Maybe glass (not fiberglass) would also work. | |> | Have you ever tried to stretch ceramic conduit? ;-) | |> Why would it need to be stretched? | | I was referring to the "just adapt the tubes to be larger" remark. If there | ain't one stock, you'd have to make the tube yourself. That seems a bit | overkill ;-)

That was in reference to the smaller (narrower and shorter) tubes used in old K&T wiring, vs. the wider (for a whole cable) and longer (to go between two joists to cross the duct) we'd need.