Larry, you've done an EXCELLENT job explaining 3-phase and transformers. I've never heard a more concise and easy to understand explanation anywhere.

PCBelarge, the reason I believe Romex is inferior can be summed up in two words:

FIRE & ELECTROCUTION

Here's my list of best to worst wiring methods:

1. RMC
2. IMC
3. EMT
4. MC
5. AC/BX
6. PVC Conduit
7. Romex
8. K&T

The problem with Romex is it offers NO protection. You can easily drive a nail or screw through even CORRECTLY (according to code) installed Romex. Even staples can be a problem.

Metal ducting can pinch Romex and said ducting can become energized. Didn't we recently read about such an accident on this forum about a guy in FL who was electrocuted installing a dryer when the ducting became energized because of nicked Romex?

The flat, parallel nature conductor placement with most Romex cable is also an issue. In the event of overload, the parallel cooper in Romex will just keep getting hot until something ignites -- similar to heating elements. Not so with the twisted nature of MC and AC and to some degree, cable installed in conduit -- chances are when the wiring heats up, it will melt the insulation, immediately tripping the OCPD. And if fire should occur, there is the additional safety factor of it happening inside the flex or conduit. By the way, with MC and AC, the brown kraft paper will stop the fire from spreading up through the cable.

A residential rewire (where the walls are not ripped down) with Romex presents all sorts of problems. First is removal of old wiring. With conduit, obviously it's a breeze. With MC or AC, you can tug on cable and pop out the staples inside the wall. It's VERY difficult doing any of that with Romex.

Fishing unprotected Romex inside walls is even more problem prone. Code says fished Romex is considered "protected" but who knows where it will end up? Will it be snaked around a sharp nail or screw? MC or AC offers "instant" protection against this. What if snaked Romex ends up against a hot water pipe or heating duct? What may happen over time? Again, not as much of a problem with MC or AC.

Romex is also too easy to kink.

There IS a reason why Romex isn't used in commercial construction, and most local codes prohibit it. Heck, Chicago sparkys have to do residential in pipe. NYC recently allowed Romex, but almost no new construction I've seen takes advantage of it.

The only good thing about Romex is it can be made into a beautiful "looking" install, like we've seen on this forum, where it looks like it was done with an iron. But conduit looks even better. MC and AC is hard to get looking nice.

Romex is nothing more than glorified zip cord.


Joe