Working with rigid

[darekelec]

Note even close to watertight when used with straight thread couplings. especially in vertical applications. The water runs down the outside of the conduit, hits the top of the coupling and then runs down the treads and ends up inside the conduit.

If field threaded .
In practical terms - how compromised is this threaded connection because of rust after a decade?
Is this a valid reason to use corrosion protection after field threading ?

 

[don_resqcapt19]

If field threaded .
In practical terms - how compromised is this threaded connection because of rust after a decade?
Is this a valid reason to use corrosion protection after field threading ?

The code requires corrosion protection for field cut threads if corrosion protection is necessary. I see rust as corrosion so field applied corrosion protection is required for field cut threads where the conduit is installed in a wet location.

300.6(A) ...Where corrosion protection is necessary and the conduit is threaded anywhere other than at the factory where the product is listed, the threads shall be coated with an approved electrically conductive, corrosion-resistant compound.

 

[Dsg319]

Shoot I’ve been receiving conduit with rust already on the factory threads beneath the thread protector.

 

[hillbilly1]

Shoot I’ve been receiving conduit with rust already on the factory threads beneath the thread protector.

What’s fun, is the rust already inside the conduit! Makes for fun pulls!

 

[busman]

They are called “ beginners couplings” LOL! But if you don’t run rigid every day, nothing wrong with needing to use them. Rigid takes planning.

I think there are some cases where Ericksons cannot be avoided, especially with long underground runs. I don't know how you would spin elbows (especially long sweep ones) on a long GRC run in a deep trench.

Mark

 

[Strathead]

Sometimes you gotta do multiple bends on a single pipe with rigid because there might not be room to spin individual pieces, or thread individual sections. Also, with EMT the couplings function like unions with rigid, in that you don't need to spin the sections together. BUT with EMT it isn't any harder to pull through a coupling than through a length of pipe, while with Rigid it is significantly harder to pull through a union than through a length of pipe. With rigid, unless you are using unions, you get only one shot for installing a piece that cannot be spun on. Choose wisely.

There is another consideration - do you start at the power end, the field end or in the middle of a run. With EMT it doesn't matter much. With Rigid there is more of a consideration. To avoid unions, it is sometimes best to start in the middle if the run requires some oddball combination of bends. If that is not the case, I prefer to start from the power end and work toward the field end. My thinking is that if something needs to be changed (now or later) it is easier to work backward from where you left off, than from where you started. The field end is more likely to change than the power end.

OP, I think this is one of the better answers for your questions. Many of us get off on tangents.

Adding to this. For every run, plan out from end point to end point before starting. If you are lucky you can do some work with 1/2" and 3/4" before having to move on to bigger conduit. Sometimes it is necessary to leave 20-30 feet or more unattached so that you can spin the next piece on.
It is nice to have a Ridgid 700 "pony" threader on hand. then you can bend before threading.
Also, especially with smaller conduits, you can "adjust" the length of a bend much better than with EMT. You can open up the 90 and bend further increasing the bend radius and lengthening the elbow. Have a Hickey on hand for this.

 

[Three piece]

Regarding the threads it seems currently unions, conduit bodies, cast boxes and any fitting besides couplings have tapered threads and couplings are straight thread. I’ve always wondered why the couplings are straight thread, and in the plumbing world what we use for couplings would be called“thread protectors”. They are to be discarded and taper thread couplings used.

On unions, I avoid them like everyone else yet I have seen a lot of time spent or loose joints left in the name of avoiding them. Sometimes it’s worth just using them.