Air conditioning condenser whip

Looking at the liquidtight flexible metal conduit requirements - I don't think you can have the 6 feet with no supports other than the accessible ceiling situation. I don't know if I see a good reason why non metallic can have the six foot with no additional supports but the metallic must have additional supports? Other than as mentioned earlier this maybe some carry over from a time when you couldn't have more than a six foot run?
which I do believe if that was a rule it has been quite some time ago.
 
kwired said:
Looking at the liquidtight flexible metal conduit requirements - I don't think you can have the 6 feet with no supports other than the accessible ceiling situation. I don't know if I see a good reason why non metallic can have the six foot with no additional supports but the metallic must have additional supports? Other than as mentioned earlier this maybe some carry over from a time when you couldn't have more than a six foot run?
which I do believe if that was a rule it has been quite some time ago.
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Doesn’t it say that the fittings used for liquidtight flexible metal conduit count as supports?
 
GAK said:
Doesn’t it say that the fittings used for liquidtight flexible metal conduit count as supports?
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Yes, but that is preceded by "for the purposes of the exceptions" the only six foot rule in the exceptions is the "within accessible ceilings" situations.

Similarities in support requirements as non metallic but not entirely the same either.
 
kwired said:
Is flexibility at most HVAC required or just convenient? Add: I see Don sees it as convenient.
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It doesn't necessarily need to be because the equipment is moving it could just be to minimize the transmission of vibration.
 
I was just looking over some job specs and noticed this section:
Section 45 Noise And Vibration Control
Use flexible piping connectors and flexible electrical conduit between all motors, rotating or reciprocating equipment and pipes and ducts and electrical conduit that are connected to such equipment.
Occupant vibration criteria are based on guidelines recommended in ANSI S2.71-1983 ... ANSI/ASHRAE Standard 68-1997. ASHRAE. 2006
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infinity said:
That type of language is pretty standard in large job spec's regarding the prevention of vibration.
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Yeah I could see running EMT to say a water heater tank instead of a flex whip but not a AC compressor.
Thats why here they go by item (2)
lengths not exceeding 900 mm (3 ft) at terminals where flexibility is required,
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The NEC is and always will be minimum standards. The least amount that you can do and still have an essentially safe and hazard free installation. Every AC unit that I hook up, whether the Carflex is 6' or not, I'll still put a 1 hole strap on it so it looks level coming out of the disconnect. It doesn't cost much or take up much time to do a better job than minimum standards. Maybe that's why I stayed really busy and had a lot of return customers.
 
infinity said:
It doesn't necessarily need to be because the equipment is moving it could just be to minimize the transmission of vibration.
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Next question does one need 6 inches for minimizing vibration? 12 inches? 3 feet? 6 feet? Does where you apply strapping change the transmission of vibration, on any particular length?

Most flexible conduit installs are said to be helping to minimize vibration transmission. IMO not too many actually are but rather are simply for convenience of making certain items a little easier to connect. Many motors do need to be able to allow for a certain amount of movement though, particularly for chain or belt driven loads as often you move the motor base to adjust tension on the chain or belt.
 
kwired said:
Most flexible conduit installs are said to be helping to minimize vibration transmission. IMO not too many actually are but rather are simply for convenience of making certain items a little easier to connect.
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It doesn't really matter whether it's there for limiting vibration or not. If someone asks it's there for vibration purposes. :)
 
don_resqcapt19 said:
The inspector needs to learn how to read the language in the code book.

356.30(1) applies to all installations where the length of the LFNC does not exceed 6'.
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This is the the inspector’s response. Haha I guess he doesn’t see it like we do.


“All installations exceeding 6’ – 2,3,4 are for 6’ or less. Strap is required.



NEC 356.30(2) Securing or supporting of the conduit shall not be required where it is fished, installed in lengths not exceeding 900 mm (3 ft) at terminals where flexibility is required, or installed in lengths not exceeding 1.8 m (6 ft) from a luminaire terminal connection for tap conductors to luminaires permitted in 410.117(C).”
 
GAK said:
NEC 356.30(2) Securing or supporting of the conduit shall not be required where it is fished, installed in lengths not exceeding 900 mm (3 ft) at terminals where flexibility is required,
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Yeah item 2 thats exactly how they interpret it here also, as typically flexibility is required for a AC condenser.
 
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