Can we run the Flexible Metal Conduit(FMC) in any length, except the length limitation for FMC that we found in Art. 348.20 and Art. 250.118? When we talk about the length limitation for FMC many people believe is 6 feet maximum and I think this is a mith and IDK why too many people have that belief?
FMC lenght
- Thread starter marcosgue
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- New Jersey
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- Journeyman Electrician (retired)
Like Roger stated there is no limit to the length for 1/2" or larger FMC but 3/8" is limited to a maximum of 6'. Over 6', over 20 amps, or larger than 1¼" trade size an EGC is always required. If flexibility is required after installation then the EGC is required for any length. Also it must be secured and supported per 348.40.
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Strathead
Senior Member
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- Ocala, Florida, USA
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- Electrician/Estimator/Project Manager/Superintendent
I believe it is also subject to the 4-90 rule.
Are you saying the 6’ maximum that people belief is because of the 4-90 rule? Just to clarify
- Location
- New Jersey
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- Journeyman Electrician (retired)
When using 3/8" FMC for making fixture whips the maximum length permitted is 6' so maybe it has something to do with that. Could be they're misinterpreting 348.20(A).
Genepires
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- Washington state
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- Electrician
while impossible to read a community mind as to why 6ft max, I can theorize. 348.24A exception 3 and 4 allow unsupportive 6ft whips for luminaires and things like motor connections. this is pretty commonly used so that 6ft probably stuck in our minds as all encompassing.
-another is maybe a glossing over of 348.20A2 Sizing minimum for smaller than 1/2 shall not be used exception allows <6ft. If you didnt read closely, maybe we just see the size and <6ft parts?
-another is maybe a glossing over of 348.20A2 Sizing minimum for smaller than 1/2 shall not be used exception allows <6ft. If you didnt read closely, maybe we just see the size and <6ft parts?
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
No, I am merely pointing out that you are also limited to 360 degrees. Technically this is a stupid requirement, IMO and rarely enforced. For example if you use a change over at the end of a conduit to flex to a piece of equipment nothing absolves you from 360 degrees. Also 300.18 doesn't have an allowance to pull conductors through the flex prior to installing it. Always wondered how you pull through a 80 degree flex connector, but I challenge anyone to walk me through where you are allowed to put the conductors in and THEN attached to connector to a junction box.
Absolutely.