Steel Conduit Question

I forget whether they were only used in the dorms or in *all* of the johns on campus. (Excluding the "Johnny on the Spot" portable toilet whose door was stolen from East Campus, the 'S' crossed out, and chained to the seated statue of John Harvard. :-)

Hmm ... I wish I had one of the dispensers. It would make a great one in the weekly "What Is It" photo puzzle cross posted between here and a couple of other newsgroups. :-)

Enjoy, DoN.

The threaded barrel couplings for RMC (rigid metallic conduit) will work, they are about 1.5" long in 3/4 size.

NEC Article 358.28(B) Threading. EMT shall not be threaded. (Exception, EMT with factory integral threaded couplings complying with

You're trying way too hard...a common half inch rigid conduit coupling

"DoN. Nichols" wrote in news: snipped-for-privacy@Katana.d-and-d.com:

It was used _everywhere_ on campus. That was a big enough market to keep them in business a lot longer than one would expect.

The MIT museum has one. I found only two links on Google:

"Pete C." wrote in news:4c39276b$0$29494$ snipped-for-privacy@unlimited.usenetmonster.com:

The stuff is awfully thin, so I'm not surprised. The thread on the fittings is apparently 1/2" NPS, and I've found a threaded coupling at Mcmaster that will do the trick. I can cut it to length on the lathe.

This will be the backup plan. Plan A at the moment is to try to remove enough wood behind the breaker box to install a conventional Romex clamp in one of the lower knockouts. This will be a royal pain in the ass, but I think it's do-able. I can then run the Romex down the wall in metal wiremold, and it will be much nicer looking than anything with conduit. It will also be totally and unequivocally to code.

The latest wrinkle is it appears that the half-wall where I need to do some tricky fishing is full of insulation. Every time I tackle a project in this house, it throws me little curve balls liek this...

Doug White

"Pete C." wrote in news:4c389300$0$29478$ snipped-for-privacy@unlimited.usenetmonster.com:

The "except when fished though inaccessible spaces" suggests that the NMSC doesn't have to be clamped to the end of the EMT, IF the exit point is inside the wall. That would allow me to run the conduit down into the wall without having to bore an oversized hole for a clamp. I'd put a plastic bushing on it to prevent any damage, and I'd still need to clamp the cable at the box.

Doug White

If you do as you indicated and use an EMT to enclosure fitting, backed by a RMC coupler and a NM enclosure fitting inside the load center that would seem to be ok, if a little unusual. Just be sure to position your entry point where you'll have clearance for the several inches of fittings and bend radius for the wires.

You don't need to go to McMaster for a coupling, you will find them at every Home Depot, Lowe's, etc. They are normal couplings for coupling rigid conduit.

Yep, pervious folks often do hinky stuff. My current house was previously owned by a utility lineman (power line janitor), fortunately he didn't do much of anything in the house, but the power in the detached shop was such a mess that I just gutted all of it and started fresh, including trenching new conduit to the shop.

And for fishing down existing walls. I ended up rewiring most of a house. Used conduit where I could and greenfield where I couldn't. County ordinance did not allow romex.

Wayne D.

Doug Miller was thinking very hard :

The amount of wire you can put into a conduit is a percentage of the cross-sectional area of the wire to the cross-sectional area of the conduit. That is why you can put more THHN wires into the same size conduit than TW. The jacket and cardboard adds to the percentage. So based on the size of the conduit and romex you could go over the allowed amount. Also 3 wire romex in generally rectangular shaped, while the conduit is round. So once again based on the sizes, you could get binding putting the romex in with the jacket, but it might go in easily without it. I don't have a code book anymore, but I seem to recall the percentage had to do with keeping air space for heat dissipation. Yes I know the wires shouldn't get hot in the first place. The jacket would add an extra layer of heat insulation. Maybe somebody else can tell me if I'm remembering this wrong.

Wayne D.

Is there an exception for that purpose? I know it has been done, but I think you're actually supposed to use a metal jacketed cable assembly. They can be custom ordered for odd conductor combinations.

I believe "Greenfield" is referred to as FMC, Flexible Metal Conduit.

NEC Article 348.10 Uses Permitted. FMC shall be permitted to be used in exposed and concealed locations.

NEC Article 348.12 Uses Not Permitted doesn't list any prohibitions that would appear relevant, only "not where subjected to physical damage".

NEC Article 348.30 Securing and Supporting: 348.30(A) lists exception No. 1: Where FMC is fished. and 348.30(B) Supports. Horizontal runs of flexible metal conduit FMC supported by openings through framing members at intervals not greater than 1.4m (4 1/2 ft) and securely fastened within 300mm (12 in) of termination points shall be permitted.

So it certainly seems that you're permitted to fish "Greenfield" just as you would MC or Romex.

Thanks. I need to update myself. Apparently it was changed several revisions back. I took my licensing exam under the 1990 code.

O.K. A photo of the oval itself, and the label from it (which I don't remember ever seeing on the rolls in the service closets) -- but not stand-alone photo of the dispenser, which would be a serious puzzle type thing for anyone who had never seen them in service. :-)

And an interesting bit of history.

Thanks, DoN.

What you've stated is correct Wayne. I view Romex jacket in conduit as a sloppy/amateur installation, and probably a good indicator that there are many problems requiring correction nearby.

Conduit isn't for stuffing non-essential material into it.

Romex jacket in conduit indicates to me that someone didn't have the sense or working knowlege to do the job any better, or properly.

I've stripped the jacket and paper off of Romex to make very short runs in conduit (by pulling it out, not slicing the length of the jacket), such as between a panel and a receptacle in a box 12" away, but using jacketed Romex in conduit is a sign of a poorly thought-out installation. The concept of actually pulling jacketed Romex thru conduit is insane.

I've seen complete idiots use SJ multiconductor cord in conduit, and I suppose some folks would defend that too. The idiots for this example chose SJ so they wouldn't have to go fetch spooled wire or bend and couple the conduit sections.. yep, no shit, two straight sections of conduit at 90 degrees, with the exposed SJ completing the "bend". This was in an industrial setting, a steel wire mill (nails, staples etc).