Pulling two #2, one #8 thru 150 feet of FMC

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Tony On Time Electrical

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Has anyone ever pulled two #2, one #8 copper wire through 150 feet of 1 inch FMC.
The plan is to pull the wire in the parking lot, then feed it through the building like an MC cable.
Not my call, but this is an effort to save money (MC cable $$$)
Would like to know what to expect and any feed back on a better option.
There will be too many turns and offsets to pull the wire after installing the FMC.
Thank You for your input.
 
Welcome to the forum.

Have you compared the cost to running it in EMT, even if you need a couple of pull boxes?
 
What's the difference in price between FMC and pulling your own conductors and MC cable? I would think that any material cost savings would be negated by labor costs.
 
petersonra said:
I don't believe the code allows you to pull the wires first before installing the FMC in place
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Your correct it doesn't, but if someone did that who would really know after it was installed? Violations aside, I'm just not seeing how it would save any money.
 
wwhitney said:
The NEC limits the FMC to 360 degrees of bend between pull points (348.26), so the above would be a violation.

Cheers, Wayne
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Thanks Wayne, you are correct. We should be under 360, our concern is the length of the run (150 feet) and the size of the wire (two #2 & one #8). Has anyone ever pulled an FMC run of that scope. Will there be resistance even with wire lube.
 
petersonra said:
I don't believe the code allows you to pull the wires first before installing the FMC in place
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Is that an issue, thanks for the information. We are concerned that the length of the run (150') and the wire size (two #2, #8) will create resistance or binding when pulling the wire, even with wire lube. Has anyone even used FMC for a run of this size.
And does the length of the run determine whether or not you run the wires first. In other words I've seen every electrician I know pre-wire FMC, Carflex, Seal tight, etc... for lengths up to 15 feet.
 
Tony On Time Electrical said:
Is that an issue, thanks for the information. We are concerned that the length of the run (150') and the wire size (two #2, #8) will create resistance or binding when pulling the wire, even with wire lube. Has anyone even used FMC for a run of this size.
And does the length of the run determine whether or not you run the wires first. In other words I've seen every electrician I know pre-wire FMC, Carflex, Seal tight, etc... for lengths up to 15 feet.
Click to expand...
If you lay the 150' out straight there should be no issue pulling in the conductors. The hardest part will be how you hold back the end of the FMC where you're feeding in the wire. Regarding pre-wiring the FMC this applies:

300.18 Raceway Installations.
(A) Complete Runs. Raceways, other than busways or exposed raceways having hinged or removable covers, shall be installed complete between outlet, junction, or splicing points prior to the installation of conductors. Where required to facilitate the installation of utilization equipment, the raceway shall be permitted to be initially installed without a terminating connection at the equipment. Prewired raceway assemblies shall be
permitted only where specifically permitted in this Code for the applicable wiring method
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infinity said:
If you lay the 150' out straight there should be no issue pulling in the conductors. The hardest part will be how you hold back the end of the FMC where you're feeding in the wire. Regarding pre-wiring the FMC this applies:
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I understand and agree with 300.18.
Our concern is resistance or binding if we try to pull the conductors after we install the FMC.
If it were my call we would get the MC cable.
I am here trying to get feedback from someone who has done a similar install.
Thanks for the great information.
 
LarryFine said:
Welcome to the forum.

Have you compared the cost to running it in EMT, even if you need a couple of pull boxes?
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Thank You Larry, I will suggest running EMT where we can, but there are two areas, that total 50 feet that are not accessible.
That's why we started talking about MC cable.
Why we are contemplating FMC for this length is not my call.
 
Tony On Time Electrical said:
Thank You Larry, I will suggest running EMT where we can, but there are two areas, that total 50 feet that are not accessible.
That's why we started talking about MC cable.
Why we are contemplating FMC for this length is not my call.
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Not accessible? Are you allowed to fish FMC?

I think it's supposed to be regularly supported and secured.

Depending on what you mean by not accessible you might be able to run some kind of UF cable in the unaccessible part.
 
Tony On Time Electrical said:
Has anyone ever pulled two #2, one #8 copper wire through 150 feet of 1 inch FMC.
The plan is to pull the wire in the parking lot, then feed it through the building like an MC cable.
Not my call, but this is an effort to save money (MC cable $$$)
Would like to know what to expect and any feed back on a better option.
There will be too many turns and offsets to pull the wire after installing the FMC.
Thank You for your input.
Click to expand...
That will be a tough pull. With THHN copper stranded, the Southwire on line calculator puts you at 32% fill with jam probability of 2.7 which they deem a high risk. In pulling smaller stuff through FMC I have found their jam probability calculation to be very optimistic. Previous comment about
securing the FMC beforehand is right on. If FMC is not secured around all bends and every few feet on straight sections, your pull will be like pushing on string. BTW FMC is worse than pipe because it is not smooth inside.
 
Tony On Time Electrical said:
Thank You Larry, I will suggest running EMT where we can, but there are two areas, that total 50 feet that are not accessible.
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Of course, we haven't seen the site so our suggestions are merely guesses.

If a cable can be fished 50 feet, the odds are that EMT can be pushed or pulled 50 feet.

You can certainly mix wiring methods along the way such as EMT to a flex to EMT to a flex to EMT, making splices in J-boxes where necessary.
 
I've done similar to what the OP is suggesting.

Not quite as large, though.

(3) #4 and (1) #8

Laid out the fmc in the parking lot, measured out and cut and labeled, pulled in with help.

Not hard at all.

Only one thing - after pulling conductors through the FMC, tape it all together really well at the ends of the flex to keep the conductors from pulling out while running it
 
James L said:
I've done similar to what the OP is suggesting.

Not quite as large, though.

(3) #4 and (1) #8

Laid out the fmc in the parking lot, measured out and cut and labeled, pulled in with help.

Not hard at all.

Only one thing - after pulling conductors through the FMC, tape it all together really well at the ends of the flex to keep the conductors from pulling out while running it
Click to expand...
Thank You, that is the plan. The concern is 150 feet. Will make sure both ends are taped.
 
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