Thanks for the tips. I didn't buy new 5hp motors as they were already on the used pump stand I bought and refurbished. Good tip on the green wire, I did that a lot when I ran new wires for my vacs. Bought red, green and white tape and just used the black wire.
Based on wash4me's above quote ... that (gpm x psi)/1460 is the limiting factor & it still does not tell us what the amps the specific motor draws when it first starts up. It seems like single phase is worse when it comes to the starting amp criteria creating the need to go to a higher amp breaker. As far as the breaker throwing ... I have read that some breakers & even between brands do not all have the same throw sensitivity. Older Federal breakers come to mind. Our friend Slash007 could be considering a Super Bay(s) with more pressure & volume if the pump part of the equation can handle it.
Should I use stranded or solid wire for the pumps? Also, I have been going back and forth between using 10 and 12 gauge wire after your post. My cable run is only going to be 25' or less, so it seems that I can get away with a lower gauge wire.. Other than that, is there a limit to how many wires I can run in the conduit? I am going to have 26-28 wires total.
I already told you the inrush current on the motor when it starts: it's not measurable. There's not a 5 or 10 second spin-up time on the motor. It's also not single-phase, so your comment there is off-topic rambling.
Stranded wire is used for flexibility. Either one will do the job the same.
MEP is right. stranded or solid is just a preference. Stranded is my preference. What about possibly using the wire out of the old pump stand? You won't know the difference between 8 10 12 14 gauge. It's irrelevant other than code requires at least 12 gauge. When you put a lot of wires in a conduit it is technically a code violation if you don't "derate each conductor". There's a procedure for this but it's really not going to hurt to run them all in a conduit and not worry about it. Carwash pumps don't run continuously and are lightly loaded. If you were going to run fans that were fully loading each motor and running all day continuously then you should derate. If you're worried about this derating it would be code compliant to run a separate conduit for each 2 pumps and then share the ground between the 2 that are run together in each conduit.
Starting inrush is 5-7 x full load amps listed on the motor but it only lasts like 1/10 of a second or something. It is already taken into account with the code recommended size of 12 gauge wire. Different breakers have different trip curves but that is just fine on a 20 amp breaker of any brand. No harm in putting in 30 amp it's just I'd rather have the money. Single phase does require more amps to run and start because it's just 2 wires instead of 3 putting power to the motor. We put in a truck bay with a bigger pump but the same 5 hp motor. It put out 5 gpm at 1250 psi and It would occasionally trip the breaker so we turned the pressure down a bit. Could have put in larger breaker i suppose.
Thanks! I searched for something like that, but couldn't find it. I was worried about putting in too many wires in one conduit. I plan on using the flexible grey conduit, probably 3/4 inch. Looks like with THHN at 12 gauge, i can fit 18 wires, so maybe I'll just use two runs and put 14 in each if they fit.
Use the metallic sealtite and you won't want that many wires in it. It is possible but a pain. 3-4 runs of conduit. It's important to keep all 3 conductors that go to a motor in the same conduit.
