what size should I run

[roger]

This thread has shined some light on this subject for me and I appreciate everyone's input. I wonder why my firm is so dead set on specifying only compression fittings and never set screw?

Sometimes old habits and beliefs die hard.

Roger

 

[infinity]

IMO steel set screw fitting are the best, especially on larger conduit. I have found that engineers who spec compression on 4" EMT have no idea that it will never be very tight. We use the ones with hex heads so that they can be super tight even with only an inch of clearance.

 

[Pharon]

This is all news to me. I wonder how everyone got it all so backwards? Must have been the same people who pushed the 25 ohm resistance rule.

 

[ActionDave]

It has always been, and still is, my opinion, that a set screw EMT coupling or connector is a better grounding connection than the grounding connection made by a compression coupling or connector. I have found many more loose or broken compression type couplings and connectors than I have set screw ones.

Agree enthusiastically and completely.

This thread has shined some light on this subject for me and I appreciate everyone's input. I wonder why my firm is so dead set on specifying only compression fittings and never set screw?

I hope you will spread the word.

 

[ActionDave]

Or you could just always make sure to run a separate EGC and not use conduit as a ground path - which I think is kinda hack, to be honest.

If you are saying that using the conduit as the EGC is hack work then I think you are wrong.
Pulling a green wire may give you warm fuzzies but that's all it does. I have seen lots of badly spliced greens.

 

[GoldDigger]

It seems to me that he was trying to say that not taking any care about the raceway continuity just because you have pulled a wire EGC is hack work, and I am inclined to agree with that.

The edge case is that, where the metallic raceway is continuous, Code requires you to do what is necessary to bond it properly whether you pulled a wire EGC or not.
But if you have a wire EGC then you can put a non-conductive raceway segment into the path if you want to, as long as you bond the transition at both ends properly to the wire EGC, which then serves a secondary purpose as a bonding jumper for the metallic segments.

 

[ActionDave]

It seems to me that he was trying to say that not taking any care about the raceway continuity just because you have pulled a wire EGC is hack work, and I am inclined to agree with that.

I'm inclined to agree with that too. I have seen such an attitude displayed by some of the "green to everything" guys I have worked with.

 

[kwired]

This is as per 2250.122(C). My question is, what do you do at the loads, splice the EGC and extend the ground to each load? I guess I am not used to this because we typically specify one EGC per circuit regardless.

All those EGC's take up space in the raceway that could have maybe been used for an additional few circuits, unnecessarily uses more copper, and if you are going to pull more then one EGC if one needs spliced or connected to they all need to be brought into the same splicing device and bonded to the box and/or device. Pulling one sized for the largest overcurrent device makes the most sense to me, but I am also one of those that is most likely to use the raceway for the EGC in most instances.

Tightening of set screws or compression nuts - people that have been on larger crews on larger projects tend to have the opinion that a fitting will not be tight, and that is probably true. Smaller crews, and especially when it gets to be a one man crew tend to have more faith in the fact that it is their installation and they are not going to overlook such things, and though they could still miss one once in a while probably do not miss very many. Pulling the separate EGC still needs the robot connection people to make good connections or it has just as much of a risk of failure.