Need the smart sparkies!

[Ex-Calif]

Totally non-RV related other than the fact I am building this property to install an RV pad - LOL...

So the well is in my property and the paperwork says it's a 230V 1 hp submersible pump. The power run is about 170-180 feet from the distribution box. I also know they ran 84 feet of 12-3 wire down the casing to power the pump cuz they charged me for it.

So I convert 1 hp @240V to amps and get 4 amps.

Then I check wire sizing for a 170 foot run and the wire sizer tells me I can use 16g copper?

Q1 - Does that sound like I did the calcs right?

Q2 - In overkill mode I am planning to run 12-3 copper in a conduit on a 15amp breaker - Does that sound reasonable?

Thanks is advance.

 

[Mark_K5LXP]

It's implied by your post that you are connecting to the run that terminates at the top of the well casing. I can't picture an electrician that would install any 240V circuit with 16 gauge wire. 12 would be minimum, 10 or 8 would be plausible if specified, 6ga for a long run. Knowing the load here I wouldn't run anything less than at least 14ga but would probably run 12ga if for no other reason that future-proofing the installation, and also mitigating voltage drop during pump startup which can be several times the running current. There's the 84 feet of wire going down the hole which needs to be added to the total run.

Mark B.
Albuquerque, NM

 

[NY_Dutch]

You also need to allow for the starting load of the pump motor that can be up to triple the running amps. Did they supply you with a box for above ground hookup? Many down well submerged pumps have the starting capacitor and relay located above ground for ease of service. I would run 12 GA direct burial if the current draw is as you calculated. Can you post the make and model of the pump?

 

[Ex-Calif]

Thanks guys - Yes there is a junction box at the well head with a 3 wire connection.

I just wanted to make sure I had not made a huge error especially with the online tool giving me the very surprising result of 16g wire. While that may be technically correct I agree I would not wire this with less than 12g, if not only that it matches up with the 12-3 running down the well.

I confused myself a bit because I had been contemplating putting in a 100amp subpanel near here and that's a whole 'nuther ball game in terms of wire sizing.

Cost and expediency wise a 240V 15 amp installation with 12g wires is gonna be a ton cheaper and I will punt the subpanel plan for much later in the property development. It's also an easier hop through the permit inspector not having to get the sub panel inspected and signed off.

@ Dutch - I don't know the pump make. Why do you recommend direct burial and not conduit. Everyone else I have pinged recommends conduit.

@ Mark - Excellent point on the 84 feet down the well had not even thought of that. Using a 250 ft run ups the calculation to 14 and so 12g makes even more sense.

 

[Jim18655]

1 HP motor should be closer to 7 amps than 4 amps. A 3 phase motor would be about 4 amps.
Where's the pump control pressure switch? If it's in the house then the power to the pump will only be live when the pump is running.

 

[Kirk]

I would run 12 GA direct burial if the current draw is as you calculated.

Conduit is protective but is probably unneeded. I would use conduit from the ground up to the box.

Where's the pump control pressure switch? If it's in the house then the power to the pump will only be live when the pump is running.

Does your pump have a pressure tank and controls? If not you should put one in to keep the pump from running all of the time.

1 HP motor should be closer to 7 amps than 4 amps.

I find it listed as 7-10a and with a start current that approaches 35a in some places and others go as low as 3.2a. Reading up it depends on the design of the pump and the distance it must lift.

 

[Ex-Calif]

It's a single phase pump according to the invoice paperwork and yes there is a pressurized tank and associated pressure controls.

Not to be rude to responders but if you are googling answers, I can certainly do that.

I recognize there is not a lot that I know about the pump so I am kinda looking for answers from people who have done this.

I already conservatively set the continuous amp load at 5amps and still got 14g so unless there is some compelling "12g is crazy and here's why" post I will call this answered.

There is also an argument to call the well driller and get the pump specs but I don't think I need to do that at this point.

 

[Matt_C]

OK Ex-cal,

Hang on tight because here we go.....

Yes, if the pump is 1/2Hp you could run it in 16AWG wire. There would be abysmal voltage drop in the system, but the pump would just have trouble starting and well pumps seldom over heat....

The 15 amp breaker makes sense because if things get strange with that pump that is down in the hole, you get warning before things are unsalvageable. Keep a spare 20x2 breaker on the shelf. (see below)

As the cable runs outside, it should be on a GFCI. If it is direct burial cable. it will be fine until something hits it on the Sunday afternoon of a holiday weekend. Have you ever been without water for three days? Conduit is cheap in this case.

14 vs 12AWG. Look at the cost difference. The thing about copper is that you only have to buy it once. If you don't buy enough, you will pay for it forever. It may also work out well if you can bury a big enough conduit to pull in 2ea-12 and 1-8 and 3-6s all in THHN (slippery jacket) and probably cheaper than UF cable (UF is direct burial). Then when you want a guest 50amp, the wire is all there.

And if you don't want it now, you can wait a few years and pull all that other copper in later.

I'm not an electrician now, but that was before I got several degrees. That doesn't make me smarter, it just means that people are more likely to believe me.

Matt

 

[John From Detroit]

I too would go with 12ga.
You go with wire that is bigger than you need. later upgrades (say to a 2HP pump) are possible.

You go with one too small and a big red pump may show up with flashing lights and firemen.

 

[Rob&Deryl]

The well at my old house had the pump hung 100’ down.
Most pumps these days don’t use the old school, in-house,starting capacitor.
The electric run was in PVC hose, buried @ 4’ (to be under the frost line - though it solves the accidental digging too) and the horizontal run was #10 from pressure switch to casing. The length was about 100’.

 

[Rene T]

Also in my neck of the woods, when burying cable like this, I’m pretty sure it has to be down a minimum depth on a bed of sand then covered over with sand then some yellow caution tape a few inches above the cable so if your in the area digging and you come across this tape you’ll stop digging.

 

[NY_Dutch]

When I was building our mountain top home years ago, the UL inspector wanted the electrical service wires buried a minimum of 24", with a 12" separation from any other wires. I ran the service wires at 36" with red surveyors tape at 32", phone wires at 24" with orange surveyors tape at 18", and my C-band satellite dish coax and control wires at 12" with another orange tape run at 6". The wiring trench was in a virtually no traffic location.

 

[solarman]

I did a pump run like that for my shop ( 166 feet ) , I would suggest 10 AWG and conduit.
are there any local city/county codes that need to be adhered to ?

 

[Scott 3]

Great reading as my house has a well. It might would be a good time to include a manual pump in case you lose power.

 

[Ex-Calif]

Thanks for all the additional input. Because I am zoned AG1 I don't technically have to follow the code (no inspections after the primary) but I will anyway.

I am planning to put the electrical 24 inches deep in conduit and for all the reasons stated above will run 12g wire. The water pipe will be collocated on top of the electric at 18 inches.

The well guy first mentioned this as if someone digs they are likely to hit water before electrical and that's a good safety thing. I haven't read the code (lately) or committed it all to memory but this is fine in terms of code.

It also means only one trench.

I am now also working with the permit person for the mobile home and she says that what I am doing is fine. Her main concern (which I am also aware of) is separation of sewer and potable water.

PS - Wanted to point out Matt_Cs post. You have given me some new info and food for thought. First of all about wire type. Conduit is more protected and it allows a non direct burial cable.

I originally planned to pull wire for a subpanel to the original well location as there are outbuildings planned in that area. The well had to be moved about 80 feet as the first hole was dry. The new location is not ideal for the subpanel so I have decided to direct wire the well and punt the subpanel to when the out buildings actually get built which could be as late as mid-next year.

By waiting until the actual garage is built I can put the subpanel inside the garage (rather than have a second outdoor panel) and run the second RV pad electrics at that time. It's a cash flow thing as well. The first RV pad (30amp) is already set up near the primary electrical panel. It was a little dumb not getting a combo 50/30 RV box but my current RV is only 30 amp anyway and there will probably never be a 50 amp RV in this first location.

Finally, I guess power loss is always a risk in a well system and my back up plan was always been to rig up a generator to run the pump even if it is just to recharge the "accumulator" type tank until permanent repairs can be done. This is also just part of the Florida hurricane strategy as well.

 

[JayArr]

I think 12/3 is the best idea, I use direct bury cable because it's easy and you can usually buy leftover lengths on Craigslist cheap. I've done it several times where the leftovers from a job are sold off for whatever they can get. In Canada it's called Tek cable or sometimes Tek90 and it meets code. It's armored and double insulated so it's almost as tough as conduit but you can't add to it later. If you're only going out to a well you probably won't need to add to it in the future.

Local codes can be wildly different but were I live they also require pressure treated wood on top of the wire, or in your case the water line. The reason is that any skilled backhoe operator will feel and/or see the wood and stop before he does more damage - if he didn't see the tape. I don't know if you want to splurge for 180 feet of 2x4, I'll leave that decision to you.

 

[Ex-Calif]

Thanks for additional input Jay. I did not see anything in the FL codes about covering direct bury or conduit wire with a wood barrier so I will probably skip that.

My "new" dilemma I am second guessing myself on is whether to just go direct bury on the wire. The trench is deep enough and it would make the job a lot easier not have to pull the wire and glue the conduit all together.

I am buying the supplies today and getting started.

 

[Scott 3]

Are you close enough to the coast that salt water could be an issue? Some areas in Florida get salinated when droughts hit. Would conduit help protect against this?

 

[Ex-Calif]

Not near the ocean if that's what you are asking. I am on the I10 corridor in northern Florida. I also doubt that salt would be a factor on buriable cable that meets FL code.

 

[JayArr]

My thought on this is that the direct bury cable doesn't have any points that are weaker than others. If the ground shifts the wire shifts with it without a breach. I've dug up my share of conduit and it always seems to fail at the joints, the long length is rarely damaged but joints seem to be the weak point.