Electrical Flex Conduit Material Choices

thomasutley · Sep 19, 2016

What do you like to use for flexible electrical conduit on metalworking machinery?

I'm nearing the end of the restoration of a WWII-era 16" x 60" metal lathe and intend to add some updated features such as e-stop switches at each end, a coolant pump with remote switch, and a DRO. I've used non-metallic Liquid-Tight flexible conduit on smaller machines in past restorations but don't know how it might hold up against hot chips and coolant.

Got any opinions one way or the other before I buy materials?

Thanks,

Tom

SAF · Sep 19, 2016

Lathe Conduits

The only thing that holds up against hot chips is metal. Be it EMT/GRC conduit or liquid-tight flexible metal conduit. On the metal flex the outer PVC covering may get small burns but the wiring will be fine.

Across the bed area it's best to use EMT/GRC across the hazard zone, and convert to flex on the ends if so required. Combine multiple control circuits in the same pipe if required.

For the DRO and coolant pump your non metallic flex is probably good enough for the intended application, as long as their out of the flight path.

Here's a WWII sample of crossing the flight path with EMT for some outlets.

Self Supporting GRC from Controls to Iron PB stations.

SAF Ω

thomasutley · Sep 20, 2016

SAF said:
The only thing that holds up against hot chips is metal. Be it EMT/GRC conduit or liquid-tight flexible metal conduit. On the metal flex the outer PVC covering may get small burns but the wiring will be fine.

Across the bed area it's best to use EMT/GRC across the hazard zone, and convert to flex on the ends if so required. Combine multiple control circuits in the same pipe if required.

For the DRO and coolant pump your non metallic flex is probably good enough for the intended application, as long as their out of the flight path.

Here's a WWII sample of crossing the flight path with EMT for some outlets.
View attachment 180710

Self Supporting GRC from Controls to Iron PB stations.
View attachment 180711

SAF Ω

Thanks for the input. I like the idea of running rigid conduit along the 8' bed for the remote e-stop and coolant pump.

jim rozen · Sep 20, 2016

My personal preference is to use liquid-tite, the stuff with the PVC outer jacket and metalic inner flex.

You do need to use the correct fittings for this. But it does a very neat job. You can fit 90s or 45s directly on the
end of the conduit.

wippin' boy · Sep 30, 2016

I like the "ultra-flex" nonmetallic McMaster sells. it's similar to what the top machine tool builders use. it holds up well. if a red hot Chip the size of an orange peel lands on it it will show damage. but the chances of melting through it in everyday use is is unlikely. I like nonmetallic because when smashed there is not the chance of short to ground that metallic has. the ultra-flex style let's you bend and turn to get it where you want it.

wippin' boy · Sep 30, 2016

I do agree with running rigid when practical

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