ET BS31 (??)

I would agree that it does not matter which you use. I assume you are installing a locking nut on both side of the drilled hole. You did not say conductor size but 3/8 does not give you much room for the conductor.

This is definitely an "over-kill" situation as each gland is just for a Foundation Fieldbus cable from a segment protector to an individual instrument within 6 meters of the junction box. The entire spec for this also adds "double compression type gland" which is good enough for explosive atmospheres, which this is most certainly not. OD will be under 3/8". They run in the 0.28 to 0.34" OD range. Spec fails to give desired model for the cable, so I am using a 0.334" OD cable in my quote.

So the ET is a "standard" British conduit thread? We have bought stainless conduit from England and it was available in NPT here.

Phys,

I have never worked with ET, but remember a time when I was working on a job in Jamaica and went into a wholesaler to ask for some conduit. When I asked for 1/2" they replied: "English Thread or US?" When I asked about the differences I was told that ET was outside diameter. Thus US's 1/2" NPT is approx. 7/8" outside diameter and ET would be 1/2" o.d. I suspect you will have some trouble if you are trying to put 1/2" ET into a box with a 7/8" hole.

--JMM

Not really as I am making the hole in the box. (electrical cabinet would be a closer description, except we are only providing a connection point for the instruments to the DCS, so the jb decription is appropriate)

That is an interesting deal with the 1/2" being the OD as that does make the ID a bit smaller than expected.