10-3 Direct Burial wiring question

[woodlandfarms]

Well, darnit... No good deed goes unpunished.

I am running some electrical to my wifes garden. 180 ft run. Wanted to run 10-3 so I could have 2 20 amp legs. Went and priced wire - OUCH. $400 for the run. No way jose. Got on Ebay and found a 200 ft of 10-3 for $150.

Well, of course, it shows up and it is stranded, not solid core. It is direct burial rated, seems freshly cut off a spool. But stranded?

Any thoughts if I can go ahead and use this or did I just make my wire purchase $550?

Carl

 

[BukitCase]

Carl, as long as the wire you have is rated for direct burial it'll work ok ( although I've not seen stranded direct burial wire) - only thing you'd have problems with is connections to outlets, which are hard to connect using stranded wire without losing some of the strands.

Best way around this is use boxes that are a bit deeper than standard, then wire nutting a short "pigtail" of solid core wire to the stranded (# 12 is fine for the solid, since it'll only be a few inches long) - do NOT try to solder these connections - although this seems like a better way, it's against code because a short can heat up the wire above the solder's melt temperature and cause MORE problems.

The short solid pigtail will easily bend into a "U" to fit the screw terminals of your outlets. If you somehow get hold of outlets that also have a PUSH in terminal, I'd not use them - some had pretty "iffy" connection, just a couple of springy leaves so not good for high current.

HTH... Steve

Oh, didn't notice you don't say whether the wire is aluminum or copper - if aluminum, I'm not sure it's OK to use copper pigtails even if you apply "NoAlOx" to the joint -

 

[MapleLeafFarmer]

how about running it as 220 to a small dist. box that has lugs for stranded wire?
Then from dist box / sub panel run your 120 lines

 

[wthompson]

i see no problem using the stranded wire as long as it's direct burial/UF. as far as the connects to receptacles, use a yellow fork connector/mechanical crimp type at the screw terminals, and use ground fault receptacles.

 

[CurlyDave]

I just finished wiring a new house, and with #6 and larger all that is available is stranded. I think you will be fine with stranded. It is easier to handle, not as stiff as single strand,

 

[magicheater]

Just remember that when running 220 on three wires and then splitting 2 110 legs off, the "neutral" is now handling the current sum of both legs, presuming both are used at the same time. Something to think about if you plan to max out the circuit. The neutral and ground should only be joined at the main box where the grounding rods are located.

 

[LarryD]

And that being said, Could I just create a ground by putting a ground post in where these wires come out? I guess it would create a ground loop? (2 Hots, a Nuetral and then tying to the 6 ft grounding rod).

Carl

Not in WA state, you have to ground back at the source. Also, if you do a sub panel, you still have to drive a ground rod there but the nuetral and ground are not bonded. Only back at the main panel as stated. The common nuetral you plan on using is fine but the two hots must have a common trip (two pole breaker) so an electrician will not turn off one leg and think all is safe, I've been there.:shocked:

Now for my personal experience, I would put it all in conduit even though you have UF rated cable. I ran a 30A circuit out to the horse pastures and with trough heaters, lighting, and fence charger it is pushing the limits. Of course the wife bought 1500W heaters for each 100gl trough so now we have 250W heaters and only fill half way during the coldest periods.
I also had the first receptacle as GFCI and ran the others off the load side of that. Even with a weather-proof box, that thing just kept giving me problems so I installed a GFCI breaker. Not nearly as much trouble.

 

[CurlyDave]

Just remember that when running 220 on three wires and then splitting 2 110 legs off, the "neutral" is now handling the current sum of both legs, presuming both are used at the same time. Something to think about if you plan to max out the circuit....

Are you certain about that? The most common way to produce 220 and 110 is with a center tapped 220 V transformer, which means that the the two 110 legs are 180 degrees out of phase with each other.

If both 110 circuits are maxed out, the current is neutralized at the junction box/sub panel. There is no current on the neutral. The most stressful situation for the neutral is where only one circuit is maxed out and then the full current from one hot wire is flowing back through the neutral.

If we start with that situation and then increase current on the second circuit, current increases in the second hot wire, but decreases in the neutral wire.

It is always safe to draw any current on either or both circuits up to the max allowable for the wire. The circuit breakers should be double pole, and sized for the wire ampacity.

Do not put direct burial wire in a conduit. It is both a code violation and unsafe. The reason is that wire in conduit does not dissipate heat nearly as well as wire buried directly in the earth. The insulation can overheat and deteriorate.

 

[mjncad]

Now for my personal experience, I would put it all in conduit even though you have UF rated cable.

In general, putting jacketed conductor bundles (e.g. Romex, etc) inside conduit is not recommended as the extra jacketing hinders heat dissipation. I'm not sure what code says about putting Romex in conduit; but I'll bet it's not encouraged.

 

[Ken45101]

Just remember that when running 220 on three wires and then splitting 2 110 legs off, the "neutral" is now handling the current sum of both legs, presuming both are used at the same time. Something to think about if you plan to max out the circuit. The neutral and ground should only be joined at the main box where the grounding rods are located.

No, that's not the way it works if properly wired. CurlyDave is correct.

When you have equal loads on both sides, the neutral current is balanced out and the neutral has zero current. If the loads are unbalanced, then the neutral will only carry the difference. For example, one side has a 20 amp load and the other side has a 15 amp load, the neutral will only carry 5 amps.

As long as you actually have 220 at the end, it's fine. Now if you wired it wrong and connected both hot wires to the same side of the feed, then yes, your neutral current would be too high, but you would have zero voltage between the two hot wires and 110 to ground on both.

To the OP: Yes, three wires without ground sounds strange.

Also consider voltage drop over that distance. If you are planning on using a 20 amp load, especially a motor, you probably need heavier wire. There are calculators that will give you the voltage drop at various currents and wire lengths.

Ken

 

[ray66v]

only thing you'd have problems with is connections to outlets, which are hard to connect using stranded wire without losing some of the strands.

There are premium "back wire" switches and receptacles. They allow you to insert the wire from the back, under a plate, and then it is tightened securely with the side screws.

That's all I use now.

They work fine with stranded wire.

They do cost about twice what the cheapo ones cost.

Curly Dave is also correct as usual. :thumbsup:

 

[firemanpat2910]

not to hijack but this thread seems to have electrical knowledge and little safety police bs. I am at work with a slow computer and i need a quick reference, want to run a 4 amp 220 volt irrigation pump. have direct bury 14 gauge wire already at the farm. how long of a run can I do, and be "safe" there is no code worries, there will be no other load on the circiut, 4 amp 220 motor 14 gauge wire already paid for, just need to know how long I can run the wire vs how far I have to plumb the irrigation.. thanks google searches took me to nothing but adds, i just need a simple chart,

 

[rambler]

240v, copper wire #14, max 4 amp load, should be good for about 280 feet.

You are on your own for 'startupload' of an electric pump, if it's trying to draw more to start up, etc. Might or might not affect your motor life, breakers popping, etc.

Drops to about 140 feet if at 8 amps, for example.

--->Paul

 

[firemanpat2910]

thanks ! that saves alot time.

 

[aczlan]

You are on your own for 'startupload' of an electric pump, if it's trying to draw more to start up, etc. Might or might not affect your motor life, breakers popping, etc.l

A "Start Kit" might help with that. It has a capacitor to help with the surge load at the motor startup

Aaron Z

 

[woodlandfarms]

As this was my thread I will follow and HiJack further cause there are so many smart people here.

I know little about wells. We had one at 100 feet but now we are on city water. I have the pump (It went into the well - the bullet shaped kind of pump).

So 2 questions.

1st, the old pump is 220 with 4 wires. The 4th wire, I am told by a neighbor, is for startup. Can someone explain what this does? There is a control box, and frankly I have no clue how all this works. Anyone give me a laymans explanation/

Second, the well is around 400 ft from the house. Plus another 100 feet down. That is 500 ft on a 10 guage wire. How is this possible? Or is it something to do with 220 not falling off as fast as 110?

Carl

 

[mjncad]

Carl:

It may not be the most accurate way of understanding electricity; but think of volts as the electrical equivalent of pressure, and amps the electrical equivalent of volume.

A 220VAC load will generally have half the AMP requirements as a 110VAC circuit, and vice-versa.

So depending on the pump's AMP requirements, a #10 AWG could very well be all that is required. Also in-rush current (a.k.a. start-up current) can be significantly higher for the fraction of a second during motor start-up; but a slow-blow circuit breaker or fuse is designed to handle the overload for that very brief period of time before tripping.

Regarding capacitor's; I think of them in this manner. A battery stores electrical energy with the intent of a slow discharge to maximize the amount of time a device can be used. A capacitor on the other hand is designed to briefly store a charge and dump it rapidly on demand. Think of a capacitor as the electrical equivalent of a fighter jet's after-burners.

 

[Ken45101]

As noted, using 220 cuts the current in half which reduces the losses in the wire. Furthermore, as a percentage of the voltage, since the voltage has doubled and the current has halved, the drop in the line is only 1/4th as much percentage wise.

To put into numbers, say you were running 110 and required 10 amps of current. If the wire resistance was 2 ohms, the voltage drop in the line would be 20 volts (amps x resistance). That's a 20% (roughly) voltage drop and likely to be too low for the motor. However, if you run 220 with the same wire, the current is only 5 amps and the voltage drop in the line is 10 volts (amps x resistance). Now you are getting 210 volts at the motor, which is only a 5% drop and is acceptable.

Ken