allowed LFMC applications

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xguard

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Can LFMC only be used where flexibility, or vibration isolation is needed? I've heard this is the case a few times but haven't found where the code clearly states this. An example I've seen recently: Rigid Galvanized Steel conduit > LFMC > Rigidly Mounted Disconnect > LFMC > to motor. According to this view the LFMC between the rigid conduit and the disconnect would be in violation but not the LFMC between the Disconnect and the motor. Thanks in advance for any feed back.
 
Here's the wording from 350.10, a strict interpretation of the wording would limit it's use to only installations that require either flexibility or protection from liquids, vapors or solids.

II. Installation
350.10 Uses Permitted. LFMC shall be permitted to be used in exposed or concealed locations as follows:
(1) Where conditions of installation, operation, or maintenance require flexibility or protection from liquids, vapors, or solids
Click to expand...
 
infinity said:
Here's the wording from 350.10, a strict interpretation of the wording would limit it's use to only installations that require either flexibility or protection from liquids, vapors or solids.
Click to expand...

But since the NEC is an inclusive document, that doesn't prohibit its use in other places, and technically any place that has the potential for water could be covered by those words. IMO, the only thing an installer should truly be concerned with (besides the inevitable blank check of "Where subject to damage") is that it is still not OK to have more than 360º of bends between pull points.
 
310.10 has a list of uses permitted, IMO that list is inclusive of all permitted installations. If it's not on the list and it is still permitted then why have a list at all?
 
IMO a strict reading of 350.10 allows us to use it almost anywhere.

II. Installation
350.10 Uses Permitted. LFMC shall be permitted to be used in exposed or concealed locations as follows:
(1) Where conditions of installation, operation, or maintenance require flexibility or protection from liquids, vapors, or solids
Click to expand...
 
infinity said:
Here's the wording from 350.10, a strict interpretation of the wording would limit it's use to only installations that require either flexibility or protection from liquids, vapors or solids.
Click to expand...
That mean you must use FMC if flexibility is required but not protection from liquids, vapors or solids?

There is many places where flexible conduit (any type) is use where flexibility isn't exactly required but is convenient.
 
infinity said:
310.10 has a list of uses permitted, IMO that list is inclusive of all permitted installations. If it's not on the list and it is still permitted then why have a list at all?
Click to expand...


Over the years here, we have explored many instances in the code that have us asking why. Take for example that the definition explains that the coating is sunlight resistant, but it doesn't mention sunlight in the uses permitted.
 
kwired said:
That mean you must use FMC if flexibility is required but not protection from liquids, vapors or solids?

There is many places where flexible conduit (any type) is use where flexibility isn't exactly required but is convenient.
Click to expand...

Since it says 'or', I see the use of LFMC permitted based on EITHER the need for flexiblility, or protection, not both, but could be both.


(1) Where conditions of installation, operation, or maintenance require flexibility or protection from liquids, vapors, or solids


​
 
I think it's only supposed to be used where it can get wet. They wouldn't call it liquid tight if it wasn't supposed to get wet. I could maybe seeing it drying out too much and possibly even shrinking if it doesn't get wet at least once in a while.


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K8MHZ said:
Since it says 'or', I see the use of LFMC permitted based on EITHER the need for flexiblility, or protection, not both, but could be both.


(1) Where conditions of installation, operation, or maintenance require flexibility or protection from liquids, vapors, or solids


​
Click to expand...

Yup.:)
 
ADub said:
I think it's only supposed to be used where it can get wet.
Click to expand...

OR any place you need flexibility OR any place you need to protect conductors from solids or vapors.

It is commonly used under the floors of computer rooms and that is a dry location.
 
iwire said:
OR any place you need flexibility OR any place you need to protect conductors from solids or vapors.

It is commonly used under the floors of computer rooms and that is a dry location.
Click to expand...

Before the turn of the century I worked in a die cast factory that ran LFMC, which they called 'Sealtite', everywhere.

It was the first conduit I learned how to bend.

:D
 
iwire said:
OR any place you need flexibility OR any place you need to protect conductors from solids or vapors.

It is commonly used under the floors of computer rooms and that is a dry location.
Click to expand...

I think it's supposed to be in a wet only environment.
 
ADub said:
I think it's supposed to be in a wet only environment.
Click to expand...

Under the raised floor it is protecting the wire from solids like dropped tools, floor tiles, and peoples feet.
If they meant to allow it for liquid protection only, why did they explicitly mention solids and vapors?
 
ADub said:
I think it's supposed to be in a wet only environment.
Click to expand...
The code does not say that and the following is from the UL Guide Information for "Flexible Metal Conduit, Liquid-tight (DXHR).
Conduit marked "80 C dry, 60 C wet, 60 C oil res" or "80 C dry, 60 C oil resistant" is intended for use at 80°C (176°F) and lower temperatures in air, and at 60°C (140°F) and lower temperatures where exposed to water, oil or coolants.
Click to expand...
 
ADub said:
I think it's only supposed to be used where it can get wet. They wouldn't call it liquid tight if it wasn't supposed to get wet. I could maybe seeing it drying out too much and possibly even shrinking if it doesn't get wet at least once in a while.


Sent from my iPhone using Tapatalk
Click to expand...
What's the lowest amount of wetness allowed and still be okay to use liquid tite? Out in the dessert it might not rain for three years.
 
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