Questions about running Wiring to pump-house for 24V DC water pump and 110V AC in same conduit

westbranch · June 2018

I finally got my ~80 foot trench dug last week to go and the #2 AL wire is ready to be cut off the spool, to length.

The 2" PVC conduit is 80 feet to the well. The well is 10 feet deep.

The rep in the supply house suggested it might be good to try to 'twist the 2 wires as they are DC carriers, but I think this might be a futile exercise due to being #2AWG over 80 feet...

I also want to have a 110V AC line in the same conduit if possible. Ac will be used in the small pump-house for lights and small tools.

I have 225 feet of 8 gauge wire salvaged from replacing a water pump at our in town house tha I will use....

I have searched and cannot find any reasons that mixing DC and is no AC carriers is not acceptable. Have also tried using some of the Conduit fill apps and it looks like I may have excess space.

Are there any issues I am missing to negate running 2 different voltages in one conduit?

Dave Angelini · June 2018

I would run my AC with type UF direct burial. You can buy a 250 foot spool of it cheap at Home Depot. Too many reasons not to mix AC and DC in the same conduit.

Reasons not too, Lightning, damaged insulation from the pull, Code, Jethro on the Beverly Hillbillies did this......

Vic · June 2018

wb,

I am not a code maven. But, for the voltages that you have noted, it IS permitted in the NEC to run AC and DC in the same conduit, IF all conductors have an insulation rating at least equal to or greater than the voltage applied to any of the conductors in that conduit.

This is often said, as the insulation rating on all of the conductors must have the same, or voltage rating voltage rating, or similar.

It is covered in NEC 300.3 (C)(1). Think that Canada uses NEC as the standard of practice ...

FWIW, Good luck, Vic

westbranch · June 2018

Well the well (pump) wire is TWU FT1 says Submersible on it and the chart states:

For open wiring where exposed to the weather, and for service entrance below ground. Approved for direct burial. Maximum conductor temperature of 60° C in wet or dry locations, for circuits not exceeding 600 volts.

so it appears that I am OK with just laying it in the trench beside the conduit... but wouldn't that have almost the same effect as being in the same conduit and starting from the house and ending in the pump-house?

I have some thin wall 3/4 inch black water pipe for a little extra protection I think I might use.. I'll also get a bit more separation underground vs laid in the same pipe

Thanks for the comments...

Dave Angelini · June 2018

The Marine code use to permit combining AC and DC. People in marinas would pick-up surges from lightning and utility surges. The loss of the DC system caused unattended boats to sink from loss of bilge pumps. This was in the 1980's.

It is a pain to also pull those size wires in the same 2" conduit. It hurts just thinking about it... Good Luck Eric!

mcgivor · June 2018

Running different class systems in the same raceway is not permitted without a barrier to separate the two, but the question is what class is a battery source. The CEC (Canadian Electrical Code ) is sometimes difficult to decipher with its 50 shades of grey ( areas), the one factor, without quoting rules, is there would be an induced signal in the DC due to being in close proximity to an AC source, for this reason keeping then seperate is probably a wise decision, if not by distance then by shielding one in a metallic raceway or other method.

oil pan 4 · August 2018

Where I work they won't run a DC motor and AC lighting power in the same conduit. The plant electrician said it is against code.
And that's good enough for me.

Questions about running Wiring to pump-house for 24V DC water pump and 110V AC in same conduit

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