2 circuts in one box/device......confusion..

[Nailset]

I'm having issues with my septic system's pump (pump's in a holding tank). The pump trips the breaker all the time. The pump is new and functions fine when powered by an extension cord on a different circuit, so a problem within the pump has been eliminated. It's my belief that there is a short in the underground wire (direct bury) due to a rotor tiller incident a few years back.

I'd like to redo this circuit with conduit (PVC scd40) and THHN. The current set-up has an overflow/high effluent alarm box outside the holding tank. There are 2 circuits running to this one box. It's not a shared neutral circuit. Two separate circuits via 12/2 w/g UF, two separate neutrals. One powers the overflow alarm, one powers the pump. I believe this to be a common set-up and it was professionally installed by licensed electrician.

Here's my questions: Can I run ONE conduit and put both circuits (4 THWN wires + ground) through that one conduit? Normally I say that's not right, but there are already two circuits running to one box anyway.

If that's not allowed with THWN, can I do it with UF and simply use one conduit for protection purposes?

Please give me your thoughts on this situation, Thanks!

 

[dave89iroc]

I don't see why not, but someone more knowledgeable than me will be in shortly

 

[teamextreme]

There's nothing wrong with running multiple circuits in one conduit. Completely code compliant and done all the time. Just need to size accordingly. 4 #12's will fit in a 1/2" conduit.

 

[kd3pc]

If you know where the tiller and the cable came in to contact, dig it up, cut out the bad section and splice it back. The kit to do this would be a lot less than redoing the whole thing.

Bests

 

[Muzzy]

Nothing to add on code compliance, but you might find it easier to pull the five wires through 3/4" conduit rather than 1/2".

 

[wyliesdiesels]

Is the pump 240v?

 

[Nailset]

Pump is 120VAC. Thanks for the replies!

 

[Nailset]

If you know where the tiller and the cable came in to contact, dig it up, cut out the bad section and splice it back. The kit to do this would be a lot less than redoing the whole thing.

Bests

Good suggestion, but that was done approx. 4 years ago when the incident happened. It worked for 2 years after that. We've been running it off a temporary extension cord set-up since. One of those jobs that gets put-off, but needs to get done.

 

[alfredeneuman]

I second Muzzy's suggestion of using 3/4" PVC rather than 1/2".
1/2" PVC is virtually useless if it has any bends at all in it. It's a major PITA to even get a fishtape through.
3/4" doesn't cost much more than 1/2" and it's money well spent for the headaches avoided