Changing raceways

[wireday]

Would like to transition from 1/2" EMT to box to LTFMC or MC to box to 1/2" EMT again. I need to get around a tight area that has plumbing etc in the way,I would flex about two/three feet. I am pulling a GEC and would ground at each box. Sound OK?

 

[Coppersmith]

You can do that, however there are direct changeover fittings like this one (to FMC) to avoid the boxes and joints.

https://www.platt.com/platt-electri...plings/Arlington/860/product.aspx?zpid=439365

If you are really fixated on using LTFMC you can attach: EMT connector - rigid coupling - LTFMC connector combo to change to LTFMC without boxes.

 

[wireday]

Thank you Coppersmith, was thinking of the LTFMC So I could just run THWN through the boxes and only have to splice the grounds.Also read somewhere my MC would need to be marked if I strip it out down a raceway.

 

[infinity]

Technically the use of a rigid coupling to connect different fittings together is not permitted due to the straight threads involved. It would be up to the AHJ to decide if it's acceptable since you're pulling in an EGC. If you can find the proper listed fittings then you won't have an issue.

 

[Ponchik]

See if any of these can apply to you.

http://www.bptfittings.com/Home/ProductFinder?sel=1100,1130

http://www.bptfittings.com/Home/ProductFinder?sel=1100,1110

There are some more on their website.

 

[Coppersmith]

Technically the use of a rigid coupling to connect different fittings together is not permitted due to the straight threads involved. It would be up to the AHJ to decide if it's acceptable since you're pulling in an EGC. If you can find the proper listed fittings then you won't have an issue.

Not disagreeing with you. Sounds legit. I'd be interested in seeing a code reference. I've observed electricians (including myself) using rigid couplings to changeover my entire career and never heard of an inspector calling it out.

 

[jumper]

Not disagreeing with you. Sounds legit. I'd be interested in seeing a code reference. I've observed electricians (including myself) using rigid couplings to changeover my entire career and never heard of an inspector calling it out.

From the UL white book:

Conduit fittings:

All male threaded fittings and nipples have only been investigated for use
with locknuts.
Fittings with internal female threads (e.g., hubs, conduit bodies, couplings)
have only been investigated for use with threaded rigid conduit.

 

[Ponchik]

Not disagreeing with you. Sounds legit. I'd be interested in seeing a code reference. I've observed electricians (including myself) using rigid couplings to changeover my entire career and never heard of an inspector calling it out.

I have done it my self too. But 110.3 to follow the instruction. It is based on the UL listing.

 

[Coppersmith]

Fittings with internal female threads (e.g., hubs, conduit bodies, couplings)
have only been investigated for use with threaded rigid conduit.

How then are we supposed to connect a PVC riser to a overhead meter hub? Or a myers hub on top of an outdoor panel?

 

[Ponchik]

How then are we supposed to connect a PVC riser to a overhead meter hub? Or a myers hub on top of an outdoor panel?

Sometimes it does not make any sense, all the electricians do it and inspectors are OK with it.

 

[Smart $]

How then are we supposed to connect a PVC riser to a overhead meter hub? Or a myers hub on top of an outdoor panel?

Use a rigid [close] nipple into the hub then a PVC female adapter.

 

[jumper]

How then are we supposed to connect a PVC riser to a overhead meter hub??

Rigid nipple and female PVC adaptor I suppose.

Or a myers hub on top of an outdoor panel?

Ditto.

This Guy from UL is the one who pointed this out to many here:

http://www.ecmag.com/section/codes-standards/fittings-hubs

 

[infinity]

How then are we supposed to connect a PVC riser to a overhead meter hub? Or a myers hub on top of an outdoor panel?

Same issue with SE cable connectors. Must be 90% of all residential services around here use SE cable into the meter pan hub, every one of those is a violation, thankfully those doing the enforcement don't care.

 

[wireday]

I do think I can get a J box onto each EMT.I realize there are pro's and cons with the transition connectors.That is why I will use the boxes with either a short piece of LTFMC or MC.

 

[infinity]

Use a rigid [close] nipple into the hub then a PVC female adapter.

Can you use a tapered threaded metal nipple into a straight threaded female adapter or do you run into the same incompatible thread issues?

 

[Smart $]

Can you use a tapered threaded metal nipple into a straight threaded female adapter or do you run into the same incompatible thread issues?

Incompatibility of the thread has little to do with it. It's simply a matter of listing compatibility. Consider the fact we use tapered thread mated with straight thread all the time with rigid or IMC conduit and standard couplings... but the tapered thread is always on the conduit and the straight thread is always on the coupling, the female side of the joint.

 

[wireday]

Do they sell a transition connector to go from MC to EMT ? would the stripped out MC have to have labeled conductors ?

 

[Dennis Alwon]

Just remember when you use the transition the bends in the LTFMC also count in the 360° maximum

 

[wireday]

Thank you Dennis, I would be coming out of a J box, around some tight obstacles and plumbing, from there its pretty much a straight shot down some EMT. Do you know if a connector is listed as a combination does that include MC ?

 

[Dennis Alwon]

Thank you Dennis, I would be coming out of a J box, around some tight obstacles and plumbing, from there its pretty much a straight shot down some EMT. Do you know if a connector is listed as a combination does that include MC ?

I was responding to the changeover fittings. Lots of people don't think about the number of turns in the flex conduit.

What do you mean by is a connector listed as a combination? If you mean is a changeover connector compliant- If it is listed then it certainly should be acceptable.