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Posted By: Joe Tedesco When are expansion fittings required? - 05/31/04 11:33 AM
[Linked Image from joetedesco.com]
Is this installation missing the expansion fittings?
Posted By: iwire Re: When are expansion fittings required? - 05/31/04 12:15 PM
I will give it a shot.

Expansion fittings might be required for the raceways in the picture.

If a concrete side walk is being poured around these raceways the inspectors I have had will not ask for expansion fittings.

Or if this is an area of the country that does not have frost heaves and settling is not expected, expansion fittings are not required.

This picture looks like a landscape area, I would expect some setting would occur.

IMO expansion fittings should have been used.

Quote
300.5(J) Ground Movement. Where direct-buried conductors, raceways, or cables are subject to movement by settlement or frost, direct-buried conductors, raceways, or cables shall be arranged to prevent damage to the enclosed conductors or to equipment connected to the raceways.

Bob
Posted By: dfe Re: When are expansion fittings required? - 05/31/04 06:47 PM
I will put my 2 cents in, I'll end up being incorrect.... But I will learn something ... That's why I am here, mistakes here do not harm anyone, or cost. Great place you have here, many thanks for letting me join.

Is this installation missing the expansion fittings? ..I don't think it needs them unless the pvc underground is long enough for it to be required.
overall it looks like a neat installation.
looking at the coupling under the main, do the join right on to 90's if so are they deep enough, are they from the utility company and not fused?. most utility's in my hood want 3' of cover ( I can't tell if they are sweeps).
Also where I work we would stub gal ridge or imc to protect the pipe from damage.

Just judging by how it's looks I would say that it meets the code for the area it was installed... or the electrician do what he was doing.

Bill

p.s Looking at it again I become concern about the vertical gutter.. Is that rated for outdoor use in the direction its installed??



[This message has been edited by dfe (edited 05-31-2004).]
Posted By: cpal Re: When are expansion fittings required? - 05/31/04 09:52 PM
Expansion joints are required wher the rate of expansion (contraction) is expected to be .25" between two fixed points. This might be between two enclosures or if the raceway can push against a stationary object.

Article 352. 44 the Table will give a resonable measurement for anticipated expansion. Also if the raceway is installed in high amb. temp it may contract in cooler weather.

ground movement requires a fitting listed for ground movement don't confuse thermal expansion with ground movement.

Also I guess we are assuming the raceway is Sch. 80 or installed in an area not subject to physical damage.??
Posted By: iwire Re: When are expansion fittings required? - 05/31/04 10:13 PM
Welcome cpal to ECN. [Linked Image]

I agree thermal expansion is a separate issue but using an expansion joint is a common method around this area to comply with 300.5(J). [Linked Image]

Bob


[This message has been edited by iwire (edited 05-31-2004).]
Posted By: Ryan_J Re: When are expansion fittings required? - 05/31/04 10:29 PM
I think we also need to know the climate of the area. Is this in Alaska? Is it in Florida? I can't think that frost heave can be much of an issue in the south (but I've been wrong before...lots of times [Linked Image] )
This picture was taken in March 2003 in Indianapolis. I posted it here to generate this discussion. I did not inspect this work, and have no knowledge of the installation.

If the fine print note to iwires reference was reviewed it would show that an expansion fitting would be OK, and or additional lengths (slack) in the feeders and laterals to allow for movement caused by settlement or frost.

Exposed runs of RNMC would have to comply with the comments related to that in Article 352 and I agree.

I am happy with all of the comments here and see where we all have something to add that helps the new persons understand.

Really is better than arguing!

The wireway "Gutter" is one designed for use in this wet location. I have a close up of the label, and will post it here when I can find it, the trouble with me is that I am always moving my pictures around on my computer.

On another note before "expansion fittings" were introduced into the NEC we were always allowed to use "Expansion Joints" but now I see that they are not allowed by 300.7(B) and the FPN calls attention to the RNMC article too.

Quote
300.7(B) Expansion Fittings (used to say Joints).

Raceways shall be provided with expansion fittings (used to say joints) where necessary to compensate for thermal expansion and contraction.

FPN: Table 352.44(A) provides the expansion information for polyvinyl chloride (PVC). A nominal number for steel conduit can be determined by multiplying the expansion length in this table by 0.20. The coefficient of expansion for steel electrical metallic tubing, intermediate metal conduit, and rigid conduit is 11.70 × 10-6(0.0000117 mm per mm of conduit for each °C in temperature change) [6.50 × 10-6 (0.0000065 in. per inch of conduit for each °F in temperature change)].

Personally, I would still allow the "expansion joint" we made using a flexible raceway like greenfield or sealtight between the runs of RMC, for example at the building expansions.

How about you other AHJ's?
Posted By: Ryan_J Re: When are expansion fittings required? - 05/31/04 11:07 PM
Quote
Personally, I would still allow the "expansion joint" we made using a flexible raceway like greenfield or sealtight between the runs of RMC, for example at the building expansions.

How about you other AHJ's?

I would and I have. I have seen EMT used in buildings that have a full structural expansion joint right in the middle of them (my city hall, for example), and I personally allowed for flex to be used as an expansion fitting.
I think this would require provisions for "Ground movement". As mentioned most people use expansion fittings for this. An instructor at a class I took said expansion fittings were not rated for "ground movement". I have used an extra amount of sand for backfill for this and I have used expansion fitings. I have also heard that some expansion fittings have pulled apart.
The verticle sections next to the main junction cabinet (it has horizontal bus bars mounted inside) are not required to be raintight or rainproof. Only the horizontal sections are required to be NEMA 3R rated for the service entrance conductors. This is by agreement between IPL and the city of Indianapolis. The PVC under the junction cabinet are placed acording to IPL specifications for IPL cables. The remaining portions are between the EC and the AHJ. [Linked Image]
I am currently doing a highschool which has an expansion joint between 2 buildings. Does this mean that every piece of conduit that passes down that hallway will require an expansion type fitting at the joint? The expansion joint falls in the middle of a corridor with a large rack of feeder conduits(2 inch to 4 inch) along with racks of smaller conduit with lighting and receptacle loads. Would the fittings be required only where conduits are physically strapped to both sides of the joint in the building? Is a rack a different demon? Wouldn't all trades be affected? Corridor already had 6 inch sprinkler main, ducts, plumbing? Thanks in advance for the replies.
Posted By: Ron Re: When are expansion fittings required? - 07/01/04 12:35 AM
The paragraphs that I find are not well known for an underground installation is compliance with 300.5(G)&(J) and 300.7 when the raceway enters the building.

300.5 Underground Installations
(G) Raceway Seals. Conduits or raceways through which moisture may contact energized live parts shall be sealed or plugged at either or both ends.

(J) Ground Movement. Where direct-buried conductors, raceways, or cables are subject to movement by settlement or frost, direct-buried conductors, raceways, or cables shall be arranged to prevent damage to the enclosed conductors or to equipment connected to the raceways.

300.7 Raceways Exposed to Different Temperatures.
(A) Sealing. Where portions of a cable raceway or sleeve are known to be subjected to different temperatures and where condensation is known to be a problem, as in cold storage areas of buildings or where passing from the interior to the exterior of a building, the raceway or sleeve shall be filled with an approved material to prevent the circulation of warm air to a colder section of the raceway or sleeve. An explosionproof seal shall not be required for this purpose.
Posted By: Ron Re: When are expansion fittings required? - 07/01/04 12:42 AM
elektrikguy,
I do not think it is a code requirement to place an expansion fitting for all raceway crossing an expansion joint in the building. I do think it is a design issue and part of most good written specifications that would come with a project.
Thanks for the response guys.The question came up at the end of the work day so I did not have time to check the specs. I thought I would pose the question here due to the interesting nature of the dilemma. When I search around the code book I am finding most refences pertaining to temperature changes. When I lived and worked up in Canada I installed pvc expansion couplings alot due to extreme temperature changes and subsequent shifting of buildings. I have never installed any above groung in a building. Will check first thing in the morning.
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