mc cable above ceiling /suspended

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steveng

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what article covers the use of mc cable?

when wiring light fixtures above a suspended ceiling, is there a maximum length of the mc cable?

can you run lengths in excess of 6' from fixture to fixture?

thnaks

steve
 
Please correct me if Im wrong but, alot of folks think that 6ft is the max that you can run flex or whips....Where this get mis guided is that IF you are going to utilize the flex for an equipment ground in leu of a ground wire, then 6ft is the max. Other wise if you have a equipment grounding conductor (EGC)pulled in the flex, then the limit does not apply.....
 
Mule said:
Please correct me if Im wrong but, alot of folks think that 6ft is the max that you can run flex or whips....Where this get mis guided is that IF you are going to utilize the flex for an equipment ground in leu of a ground wire, then 6ft is the max. Other wise if you have a equipment grounding conductor (EGC)pulled in the flex, then the limit does not apply.....
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That is true for FMC.

But for MC is there is no length requirement at all. The only requirement for MC is that fixture whips be no longer 6' from the last support.
 
ItsHot said:
(mc) Miracle cable! Throw your benders away!!:D
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In this area MC is very common. We have a major manufacturer (AFC) in our backyard and MC dominates the market over pipe methods. We still use pipe of course, but not nearly like the rest of the nation does.
 
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Mule said:
Please correct me if Im wrong but, alot of folks think that 6ft is the max that you can run flex or whips....Where this get mis guided is that IF you are going to utilize the flex for an equipment ground in leu of a ground wire, then 6ft is the max. Other wise if you have a equipment grounding conductor (EGC)pulled in the flex, then the limit does not apply.....
Click to expand...


OK since you asked I'll tell you that you are wrong. :wink:

There is a 6' maximum length associated with the use of 3/8" FMC whether you install an EGC or not. Look at 348.20(A)(2).
 
infinity said:
OK since you asked I'll tell you that you are wrong. :wink:

There is a 6' maximum length associated with the use of 3/8" FMC whether you install an EGC or not. Look at 348.20(A)(2).
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Okaa, Thanks....I guess around here nobody stocks 3/8 FMC flex, or what I call Greenfield, (no wire pre-installed)...I've only seen 3/8 sizes in MC type (wire installed)....So remember I'm small town and dont see the as much as you guys..........:smile:

So my point would have been, (being better explained), would be 1/2" or larger with or without an EGC would be a factor in the 6ft length restriction???? right ? wrong?
 
Mule said:
So my point would have been, (being better explained), would be 1/2" or larger with or without an EGC would be a factor in the 6ft length restriction???? right ? wrong?
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You still cannot use 1/2" of larger FMC without an EGC in lengths longer than 6'. There are also other restrictions. Take a look at 250.118(5).
 
infinity said:
You still cannot use 1/2" of larger FMC without an EGC in lengths longer than 6'. There are also other restrictions. Take a look at 250.118(5).
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We are on the same page......:grin:
 
Rob

Rob

infinity said:
You still cannot use 1/2" of larger FMC without an EGC in lengths longer than 6'. There are also other restrictions. Take a look at 250.118(5).
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Rob, we have a ec doing a job for us who is using 3/8 mc with ground running in excess of 10' wiring light fixtures, the inspector allowed this work,
what specific article covers this exception? do you know?

am i understanding you correctly?

steve
 
steveng said:
Rob, we have a ec doing a job for us who is using 3/8 mc with ground running in excess of 10' wiring light fixtures, the inspector allowed this work,
what specific article covers this exception? do you know?

am i understanding you correctly?

steve
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MC in any size as far as you want, 3/8" FMC very limited in use and length.
 
The only problem I've ever run into with MC is having an inspector turn down a short run of 12-2. He stated that since it was installed below 7' in height it needed to be protected from physical damage. I'm not certain what fate he expected it to come to being securely strapped on the perimeter of a phone board in a com/data closet and I'm still looking for the code (city or NEC) that lists a "7 foot" rule. Oh well, should have used pipe and pulled an EGC from the get go.
 
steveng said:
Rob, we have a ec doing a job for us who is using 3/8 mc with ground running in excess of 10' wiring light fixtures, the inspector allowed this work,
what specific article covers this exception? do you know?

am i understanding you correctly?

steve
Click to expand...

3/8" FMC is limited to 6', no exceptions.

348.20 Size.
(A) Minimum. FMC less than metric designator 16 (trade size ?) shall not be used unless permitted in 348.20(A)(1) through (A)(5) for metric designator 12 (trade size 3/8).
(1) For enclosing the leads of motors as permitted in 430.245(B)
(2) In lengths not in excess of 1.8 m (6 ft) for any of the following uses:
a. For utilization equipment
b. As part of a listed assembly
c. For tap connections to luminaires as permitted in 410.117(C)
(3) For manufactured wiring systems as permitted in 604.6(A)
(4) In hoistways as permitted in 620.21(A)(1)
(5) As part of a listed assembly to connect wired luminaire sections as permitted in 410.137(C)
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