allowed LFMC applications

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xguard

Senior Member
Location
Baton Rouge, LA
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.
 

infinity

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Location
New Jersey
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Journeyman Electrician
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
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
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.

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.
 

infinity

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Location
New Jersey
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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?
 

iwire

Moderator
Staff member
Location
Massachusetts
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
 

kwired

Electron manager
Location
NE Nebraska
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.
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.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
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?


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.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
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.

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


 

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
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
 

infinity

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Location
New Jersey
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Journeyman Electrician
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



Yup.:)
 

iwire

Moderator
Staff member
Location
Massachusetts
I think it's only supposed to be used where it can get wet.

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.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
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.

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
 

ADub

Senior Member
Location
Midwest
Occupation
Estimator/Project Manager
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.

I think it's supposed to be in a wet only environment.
 

GoldDigger

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Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I think it's supposed to be in a wet only environment.

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?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I think it's supposed to be in a wet only environment.
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.
 

ActionDave

Chief Moderator
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Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
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
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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