LFNC Conduit on boat dock

[Dave Thomas]

In 1996 a PV system was install by a PV contractor on our covered metal dock on Beaver Lake, AR (Corp of Engineers, LR District) It has 2 PV panels above the roof, a weather tight metal box with an 120v inverter and two 12 volt storage batteries. Only one GFI 120v WP receptacle & fused disconnect is mount outside the WP box. All wiring on the dock for lighting is 12V DC run at the roof in LFNC conduit with wet location DC lights and wet location boxes and switches. The conduit is fasten to the dock structure 3' or closer per NEC 356.30 Securing and Supporting.

Licensed electricians have inspected the system on three separate occasions for dock renewals and approved it. As did the Corp. Our current renewal inspection letter from the Corp say that all the conduit on the dock must be removed and replaced with either rigid schedule 40 or 80 PVC. Can anybody explain why this is? And even harder, what sense it makes? Thanks

 

[GoldDigger]

LFNC may not protect well enough against physical damage. Or at least your AHJ thinks so.

mobile

 

[Dave Thomas]

LFNC may not protect well enough against physical damage. Or at least your AHJ thinks so.

mobile

Manufacturer's info all note some potential for "physical damage" but how likely is it in this case? Most of the runs are in the lip of a z purlin 16' feet in the air and the switch legs are mounted on the back of the column away from the walkways. I realize that potentially drunk wet people in bathing suit can be dangerous but really!

The installer claims under:

356.10 Uses Permitted.

LFNC shall be permitted to be used in exposed or concealed locations for the following purposes:

(1)Where flexibility is required for installation, operation, or maintenance.

(2) Where protection of the contained conductors is required from vapors, liquids, or solids.

(3) For outdoor locations where listed and marked as suitable for the purpose.
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A. Floating boat dock move and vibrate under wind and waves. Because of that flexibility between devices fixed to structure and conduit is desirable.

B. Water tightness trumps physical damage because damage potential is minimal. Better to maintained in single joint proof runs from devise to devise & be able to make horizontal & vertical bends.

C. Gluing rigid pvc off a ladder on a floating platform is more dangerous to installer and assembly on deck limited.

D. There is no life safety issue! It's 12 volt DC, backed on boat trailers into lakes by the millions each day.

Hey, I know you're just giving your expert opinion, thanks. Just hoping to hear something more definitive.