So, Would I be better off converting the pump back to 110. Well is only used
for house use. Single occupant. Have 7.5 hp pump for irrigating pasture and
yard. It's located elsewhere. And how do I figure load?
Doug Miller wrote:
That certainly would eliminate the issue with not having enough wires for both
240 and 120. Still doesn't fix the problem with buried Romex (if indeed that's
what you have).
Total nameplate amperage ratings of everything you plan to put on the circuit.
For incandescent light bulbs, divide wattage by 120 to get amps (e.g. 60W
light bulb draws 0.5 amps, 100W bulb = 0.83 amps, etc). For fluorescent
fixtures, if the amperage is not marked on the fixture, do the same
calculation as for incandescents, then add the nameplate amperage of the
ballast (it'll be on a label on the ballast). Not perfect, but close enough.
Doug Miller (alphageek at milmac dot com)
Important to note that at first glance type UF cable looks a lot like
type NM cable a.k.a. Romex. Best to read the printing on it to see what
it really is. Also important to know the gauge wire since if you want a
subpanel you probably need a heavier gauge wire such as 10ga to make it
My recommendation is to replace the wire with a run of PVC conduit
(cheap stuff) and pull new THHN wire of a suitable gauge such as 10ga
(possibly 8ga if it's a long run) so you can install a 30A six space
subpanel (also cheap) in the shed to feed the well pump, lighting and
Okay Kaye, we need to know exactly what you're dealing with. You mentioned
Romex buried underground. If it really is Romex (NM) and not UF then you
are going to need to change it anyway. Romex is not rated for underground
use and sooner or later moisture will get inside the conductors and they
will just arc in the ground until the connection is broken.
If it is actually UF you have that is good. It is approved for direct
burial and hopefully it is at least 18 inches underground. If it is UF we
need to know what size is the wire. Is it #14, 12, 10? How many insulated
conductors are there? One white, one black, one red? Hopefully there is a
bare or green grounding conductor also. We also need to know the horsepower
of the pump and the voltage it is currently wired for. We also need to know
the approximate length of this wire from the source to the pump. We also
need to know what is at the source for this circuit. Is it at your main
panel where the meter is located? Is it on a two pole circuit breaker?
What size breaker? Pictures would be very helpful.
With good information perhaps we can advise you of a possible solution that
will be safe.
Right now based on what you have already told us I'm thinking that the whole
circuit needs to be trashed. I would suggest installing a 1" or 1 1/4" PVC
underground conduit and pull in a 40 or 50 amp circuit with four conductors.
Install a subpanel in the pumphouse and feed your pump and everything else
Thanks John, I will get down in the well tommorrow and try to answer all
these questions. Will also take pictures. I wnat to do this right, but the
easiest way possible.
Many Thanks for your patience.
John Grabowski wrote:
Yes but the utility service is "wired" much the same way. The utility
neutral (both 240/120 and for the primary voltage) is grounded at every
transformer and (in most places) at every meter or service entry point.
But what the utility does to get the power to your panel isn't covered by
"the code." But that arrangement (with multiple connections between
neutral and ground and no separate ground connection) is generally
considered to be reasonably safe.
If the OP is thinking about doing this on the QT, the important question is
just how BIG the neutral/ground wire is. A secondary question is whether
his well pipe and the casing are plastic or metal. If his well pipe and
casing are metal any ground rod placed in the area would be for purely
cosmetic purposes as the well itself it likely better than the "utility"
If he wants to "do things right" it's not hard to find 10/3 w/ground
waterproof cable in areas with wells. When my pump failed, the "well guy"
replaced the cable. (He didn't want to worry about the condition of the
old stuff.) I now have a 200' roll of 10/3 w/ground. If I needed some
good sized underground wiring, I would not hesitate to use that stuff.
In NO case should he consider using a step up transformer. Keep the 240
volts to the pump and use the transformer to provide local juice.
Consider putting a power switch (or CB) before the transformer as the
transformer will continually consume a few watts of power regardless of
load. The next question, of course, is whether to bond the secondary
"neutral" to ground.
Conceptually it _could_, presupposing that the existing ground
was insulated (it isn't, because it's romex/romex-like
(eg: NMWU/UF)), a sub-panel was installed, and a ground rod
(or two) installed at the outbuilding. Tho, that would probably
cost more and be less flexible than the alternative (running new
4 conductor wire).
Age and Treachery will Triumph over Youth and Skill
He did know what he was doing. You just failed to specify that you
wanted additional capacity for expansion. Before you start messing
around with trying to get different voltages and a nuetral out of your
current set up, how much total power can you pull over the existing
wire? Even if you had four wires, the hot leads are probably sized
for the pump, which would leave you no excess capacity anyway.
You should break out the old shovel, and put in a new feeder line
to a sub-panel in the shed, and re-route the feed to the well
pump through that.
Failing that, mount some solar panels on the shed, and or
feed a UPS through a transformer.
Note that many wells can't deliver water fast enough
for fire-fighting purposes anyway.
Systems that deliver 7GMP at a mere 40 PSI with 50Gallon
pressure tanks aren't uncommon.
You really need a cistern
with at least 500 gallon capacity, and a pump that can
deliver 30 GPM at at least 75 PSI.
A better system would be 3-5,000 gallon reservoir,
and 50GPM at 100+ PSI.
I'm sorry I've been away from this so long. I looked in the breaker box on
the service pole and what I saw really scared me. Needless to say, I will be
digging and laying new wire in PVC out to the new shed. The distance is only
ablut 30 feet (probably less). I've tried to downlod pictures of the breaker
box and wire, haven't had too much sucess. I do have picts of my deck,
bathroom remodel, the old well topper and such in the photo album. Not sure
how to post a link. Anyway guys, I really appreciate all the advice and as i
get closer to running new wire, I will be back to ask more questions.
Message posted via HomeKB.com
I hope this works, here are links to pictures of the original well topper
with the service pole in the background, the breaker box (grey wire is the
one running to the well house.pump), and the as yet unfinished 8 x 12 new
green house shed that I am building.
real class electric work there.......
trouble is they failed the class.
I once found 2 lengths of romex tied in a knot with wirenuts and no
box in a wall. apparently someone ran out of wire so they tied it
We were gutting the house at the time, after a fire. there was so much
bad wiring i was amazed it hadnt burned from that.
a cat had knocked over a lamp.......135K in building damages not
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