360 degree bend rule

[Smart $]

Smart,
I believe that the REs for classified locations have tapered theads and those are the only ones that I use.
It applied to all conduit and cable fittings with straight threads.
Don

I think it's great that you use RE's with tapered threads (i.e. explosionproof) even when not required. However, I'm talking all RE's, not just the ones you use. Steel City RE's (the ones not rated explosionproof) have straight male threads. Just exactly where are these supposed to be used if you can't use straight-threaded fittings with taper-threaded ones? And last time I checked, threaded couplings are fittings.

[EDIT to add...] For clarification, I use the term "RE" loosely, as we do locally, and that is to mean both Reducing Bushings (RB's) and Reducing Bushings—Explosionproof (RE's).

 

[George Stolz]

I have no idea how you can read that sentance and arive at the conclusion that you can not change raceway types.

I can't see how you can read the pair of sentences and conclude that it does grant permission to change raceway types.

If the first sentence is taken as forbidding a changeover in normal situations, I don't see how the term "the raceway" mentioned in the second sentence can be taken to mean two different wiring methods.

I'm in a mind to drop it if you are.

Again I will point out that what I see happening in real life and what the NEC requires may not always match up.

As always.

 

[LarryFine]

A pipe is just a raceway to protect the conductors within.

I disagree to a great degree.

A conduit is as much for protecting the environment from the electricity as it is for protecting the wiring from the environment (depending somewhat on the application, of course).

Remember, the #1 danger of electricity is fire, not electrocution. National Fire Protection Association. Otherwise, why would a concealed wiring system require conduit?

 

[Smart $]

...and you'll note that there is no similar provision in Articles 350 (LFMC) and 356 (LFNC).

We do not need one, 300.18 applies to all raceway installations.

I did not say we do. I just suggested to GEORGE to note 350 and 356 do not make reference to 330.18. Must you continually read something ulterior into my written words trying to make issue of something that is not?

Raceways shall be installed complete between outlet, junction, or splicing points prior to the installation of conductors.

A change over from one raceway to another regardless of it being listed or an angle connector is not a outlet, junction, or splicing point.

I expect some would have a mind to twist this so that a junction is a junction of flex to pipe but that would mean every coupling in any raceway is also a 'junction point' making 300.18(A) worthless.

Well... sorry to say, it is worthless when it comes to angle connectors.

And just what are we supposed to do when we have to use elbows...

View attachment 271

Where required to facilitate the installation of utilization equipment, the raceway shall be permitted to be initially installed without a terminating connection at the equipment.

This tells us we can forgo the general rule at the equipment termination, not near it, not within sight of it but at the equipment.

This picture from Smart is IMO code complaint, we could pull the 90 apart at the equipment.

Afraid not. The way the latter part of 300.18(A) is written one cannot pull the 90? connector apart at the equipment. The 90? connector is part of the raceway, and not part of the equipment. The "terminating connection" is the insertion of the connector into a knockout hole and securing with a locknut on the inside, or in the case of a hub on the equipment, threading the connector into the hub (though according to Don's reference to UL standards, this would not be acceptable usage).

This picture from George is not IMO code compliant as he intends to break the 90 away from the equipment.

http://img.photobucket.com/albums/v334/georgestolz/Electrical/RTUdilemma.jpg

Of course what I feel the NEC requires and what really happens in the field does not always match up.

Wow! All that to get to your final remark

 

[Bob NH]

Carlon Products Made for Multi-Method Raceways

Carlon Products Made for Multi-Method Raceways

"I can't see how you can read the pair of sentences and conclude that it does grant permission to change raceway types.

If the first sentence is taken as forbidding a changeover in normal situations, I don't see how the term "the raceway" mentioned in the second sentence can be taken to mean two different wiring methods."

I have at my desk a hardware product that suggests that there is intended to be a means to change raceway types in mid-run.

I have a Carlon 3/4" Liquid-tight Flexible PVC Conduit Elbow that is marked with a UL Listing E155504 that also says 4M68 Wiring Assembly. I don't know what the different UL numbers mean.

It consists of an 8" length of FNMC-B with male adapters screwed into each end AND Carlon 3/4" female PVC conduit adapters (thread to socket), screwed onto the FNMC adapters with an O-ring.

The use is described as "0-90 degree bend and offset applications", "Change direction of conduit as required"; and "Suitable for applications in accordance with Article 351 of 1999 NEC". My 2005 NEC doesn't contain Article 351 so I don't know what that reference means.

Based on the configuration and designation of use of this part, it can only be applicable to changing the method of wiring in the middle of the run.

 

[Smart $]

...

Based on the configuration and designation of use of this part, it can only be applicable to changing the method of wiring in the middle of the run.

EMT to Flex adapters suggest the same...

 

[don_resqcapt19]

Smart,

Just exactly where are these supposed to be used if you can't use straight-threaded fittings with taper-threaded ones? And last time I checked, threaded couplings are fittings.

Based on the UL info there would be no use for those RBs. Are they listed?
Don

 

[Smart $]

Smart,

Based on the UL info there would be no use for those RBs. Are they listed?
Don

Yes, they are listed?UL File No. DWTT.E23018

http://www-public.tnb.com/ps/endeca/index.cgi?a=nav&N=4294955167

Perhaps these are some more instances of those "intended-for-use-with-tapered-threads" items, like couplings...???!!!

 

[don_resqcapt19]

Smart,
It is interesting to see that guide DWTT says that all fittings listed under that guide are suitable for grounding. That was the main objection in the other article...that the straight male threads would not provide a suitable bonding connection when used with threaded conduit fittings.
Don

 

[Smart $]

Smart,
It is interesting to see that guide DWTT says that all fittings listed under that guide are suitable for grounding. That was the main objection in the other article...that the straight male threads would not provide a suitable bonding connection when used with threaded conduit fittings.
Don

While I am no expert in standards, I certainly can see the fault in their premise. We see grounding through RMC runs everyday, where taper-threaded conduit ends are mated with straight-threaded couplings. I don't mean to imply mating tapered or straight threads, respectively, do not provide a more sound connection, both mechanically and electrically, because they obviously do. However, how can they justify it is ok for some mismatched threads and not for others. Then when you bring LFNC and other non-metallic conduits into the discussion, there's no electrical bond involved with the mating of threaded fittings.

 

[glene77is]

Responding to the 'Poll' diagram.

IMO, the 'INTENT' of the NEC is related to 'Re-Pulling' and maintenance.
IMO, the 'Poll' diagram does not indicate a normal installation,
rather it shows a technically possible installation,
which may require an interpretation.

---------------------

Response to a 'Technically Possible' installation:
If the two Sealtite sections are connected 'At The End of the Initial Pull',
and this part of the job is 'Complete',
;Then the 'TOTAL' length of pulled conduit
could become 'Un-Pullable' for future maintenance purposes.

----------------

Response to a Common Instation:
However, we commonly do the raceway installation
to a Junction Box adjacent to the Yet To Be Installed Equipment
and we leave the Flex and it's 90 To Be Installed After
the equipment is set in place by the millwrights.

; If the two Sealtite 90's are for entrance into the equipment,
then they are not to be counted in the 'TOTAL' run of raceway.

; If the two Sealtite sections are used for connecting into equipment,
and left un-installed to the Raceway at the time the wire is pulled,
then they are obviously only for use in connecting into the equipment.

---------------------------

To which I add IMO,
I think the 'Poll' diagram has stimulated a great deal of 'interpretation' in this forum.


glene77is

 

[Rockyd]

I disagree to a great degree.

A conduit is as much for protecting the environment from the electricity as it is for protecting the wiring from the environment (depending somewhat on the application, of course).

Remember, the #1 danger of electricity is fire, not electrocution. National Fire Protection Association. Otherwise, why would a concealed wiring system require conduit?

In raceway/conductor selection, I thought we chose each by what the environment dictated us to use. Pipe affords protection to the conductor from things that happen in the "what if" scenario, imagined to the worst case, normally. In "oil patch" work,where it's "qualified person", rules have changed the way things happen at plants. Cable tray and miles of MC are the norm. Reason being - the cables are designed to handle the protection of the conductors from the environment, and because it has limited access, nothing is going to physically endanger it.

XHHW-2 is pretty much the standard in oil patch, MTW on mechanical things, THHN/THWN in most commercial. This is craft logic. As one poster 's signature so wryly notes - Just when they make it idiot proof, they make a better idiot! It's what causes fires. I'd bet you dollars to doughnuts, that most fires are the results of non-qualified hacks.

A small percentage of electrical fires are accidents, but believe a lot are cause by the "Oh I saw it on Mcguyver, or they think they're Jack Bauer. At that point, that $75 dollar an hour electrician, looks pretty cheap, compared to the $100,000 damage problem they are standing in the driveway looking at, shivering in bedroom slippers.

 

[Smart $]

...suitable for grounding. That was the main objection...
Don

Another recent post brought up the issue of RMC/Coupling/LFMC connector transiiton and pointed out 300.15(F). How does 300.15(F) fit into your overall assessment of the issue?

 

[don_resqcapt19]

Smart,

Another recent post brought up the issue of RMC/Coupling/LFMC connector transiiton and pointed out 300.15(F). How does 300.15(F) fit into your overall assessment of the issue?

The wording requires the use of a fitting designed to connect the two raceways. I know that they are available, but they are, at least in my area, rarely seen in the field. 300.15 would prohibit the use of a coupling and flex connector to make the transition.
Don

Don

 

[dlhoule]

I see many different instances where LFC is attached to box with a 90 degree fitting run up across and down into another box with a 90 degree fitting. If it isn't code compliant to pull LFC out of fitting as opposed to taking lock nut off to pull fitting from box; then it is not code compliant to have flex run in this manner because you can not pull around the two fittings without putting excessive strain on the wires.:roll:

This method is used because one box is stationary and the other moves horizontally back and forth. The moveable box is on a machine, but it would seem to me to be code compliant to remove flex from fitting for pulling wires.