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Author Topic: OT Question for the Electrically Enlightened.  (Read 2638 times)
NJT5047
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« on: March 12, 2007, 04:47:32 PM »

Being more creative than smart, I've made a discovery that has sorta resolved one issue but may have the potential of causing great grief. 
This is an abstract electrical question if there ever was one. 
I've got this outbuilding that had a buried two wire 120VAC wiring system that was attached to another building with 250A 240VAC service.  We wanted to install a 220V well pump down at the out building which is about 200' from the "real" service. 
We needed a common.  Burying an additional wire will be very difficult since the power, cablevision, phone lines and the two-wire 120V service is buried between the two buildings...the power pole with all this service is about 3' from the back of the outbuilding.  200' is a long way to hand dig a ditch too.
In order to shorten this story, what I've found is that apparently the power company pole transformer common is also common to the power pole anchor cable (guy wire?).  We tossed a single automotive cable to the cable anchor and viola....got a ground. 
What this gave us was 110V legs from the 220.  I moved the common leg to make a 220VAC circuit, which worked great for the well pump motor.  We drove an 8' copper ground rod into the ground at the building to give some lightning protection (??).  The box is grounded.   
Obviously no 110V was available with this setup...however, jumping from the ground rod to the power pole anchor screw allowed a "real" common...and 110V applications were restored. 
My question is what's gonna happen if lightning hits the power pole?  Are we going to donate a building to nature?   
I didn't leave this "bond" between the power pole (just happens to be right behind the pump building) and the ground rod.  But, how many ways could this screw up my life...or to put it another way, is the common on the power pole guy wire the same as the common that feeds the service box?   This is a single phase circuit that's at the end of a spur that's way off the main road. 
HuhHuh?
Somebody hep me!   Wink
Not fried yet, JR

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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« Reply #1 on: March 12, 2007, 05:24:30 PM »

I usually don't pretend to be an electrical expert but, in this case, I am going to make an exception.  Grin Grin Grin Grin Grin Grin Grin Grin Grin Grin Grin


One obvious problem is if you have an internal problem with your well pump motor, it will short to ground through the plumbing. Hopefully, it will find that ground before it finds you.  If it doesn't, can I have your bus?  Grin Grin  JUST KIDDING!!

The pump motors I have seen have a neutral & a ground (4 wires). My opinion is you are courting disaster with this setup. Of course, my opinion and a dollar will get you a cup of coffee is some not very exclusive places.

I am sure some real electrical experts can give you the real story.
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'82 BlueBird WanderLodge PT40 being rebuilt
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NJT5047
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« Reply #2 on: March 12, 2007, 06:23:42 PM »

The pump's fine.  It works with and without the temp common.  It's a three wire, 230V non-control box type pump.  Got a ground rod for any issues with the pump motor. 
What didn't work without the temp common was the 120V lights that are in the building.   They work with the temp common, and they don't without. 
I've got a home wiring code book around here somewhere.  Gotta look at that.   
I know that we are going to have to dig another lead between the buildings.   Just interested in an explanation of what I have "discovered."   
 
Thanks, JR




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JR Lynch , Charlotte, NC
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"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
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« Reply #3 on: March 13, 2007, 06:01:14 AM »

Hey JR,

Yes it will work, youv'e proven that.

But you should get that wire run. The code guys will be chiming in soon.

You want a straight connection to ground (power companys)  not a ground rod.

The down guys are usually bonded by the power company to ground to give a little blast of lightning a good place to go. 

My experience with lighting is that it likes to take out stuff where it hits and on the terminating ground of an electrical feeder system.

Have Fun!

Cliff
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« Reply #4 on: March 13, 2007, 07:20:30 AM »

The easy way is just get a SOLA or equivalent 220/240 to 110/120 volt transformer and run the lights and stuff in the building
off that. Then the only ground that you need is one on the transformer-light 120 volt panel.

The transformer will give you an isolated neutral ( which is the correct way ).

The 220 volt windings on the transformer do not need a 3rd wire for ground since it will be across the 2-hot legs
to get the 220 input.

I don't want to get into a war over this but facts are facts. Electrical distribution systems all use tranformers to boost voltages
up to reduce current draw in order to send power long distances. Then on the other end place another voltage reduction
and current increasing transformer to get to your required voltage and current capacity.

A hydropower plant generator output is 15,000 volts, That is stepped up to 500,000 volts or higher at a reduced amperage
to be sent long distances. It is sometimes stepped up to 1,000,000 volts or more.

Banks of transformers tap into the high voltage low current lines, convert the voltage down which in turn increases the available amperage at a given voltage.

That transformer on the utility pole may be running an input of 7,500 volts ( squirrel zappers ) and it steps the voltage down to 120/220 volts at usually 15 to 20 kw depending on how many houses are hooked to it. ( aka 150 to 200 amp service! )

If you take the 220 you can step it down ie; 15 amps @220 volts = about 30 amps @110 volts (or 120 volts depending on what your input is ).

You would ground the transformer case to a ground bond like a well casing. Then run the neutral and hot leg to your sub-panel
to feed the lights and outlets in the building. Keeping in mind that you will be limited to about 3,000 watts or about 30 amps if you get a good size transformer.

The rule is; The higher the voltage the lower the amperage, The lower the voltage the higher the amperage.

The same holds true for Inverter battery banks. The end result is usable watts/kilowatts at the outlet.

I once worked on telephone equipment power systems. We had 48 volt converters that took 48 volts @ under 2.5 amps
and made 5 volts d.c. at 50 amps output. Neat stuff them transistors......
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« Reply #5 on: March 13, 2007, 08:31:54 AM »

To discuss whether a separate ground wire is needed, I offer the following.

The electrical code has changed in this area - maybe a couple of times.  What does this tell you other than the experts cannot agree.  I talked with a number of electricians and electrical suppliers, with no common agreement.

Since my subpanel was about 100 feet from my main, I did not run a separate ground wire.  I installed a ground rod.  The reasoning was this is how the power company distributes electricity.  Between houses, they do not worry about ground loops so they do not run a separate ground wire.

Ed Roelle
Flint, MI
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Hartley
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« Reply #6 on: March 13, 2007, 07:58:33 PM »

Running an extended ground lead could allow the ground to float at the far end due to resistance.

The ground rod on the remote subpanel is the correct way to do it. ( you can run the extra wire but would still
need the ground rod or run a line over to the metal well casing (we use them here in Florida all the time.)

With the only exception possibly being in marine environments where there is no place to sink a ground rod.
( like out on a boat dock or similar ) A heavier grounding circuit is required to be contained in the feed cable
assembly conduit. ( since most use PVC which is non-conductive a ground bond is added ).

So as to not get into technicalities. Unless you have a MEGGER conductivity tester to test the ground conductivity, using a ground rod is the least that you would want just for safety. ( if the Power company uses them, then it must work. )
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NJT5047
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« Reply #7 on: March 14, 2007, 07:09:28 PM »

Thanks for all the info....Dave, regarding the well casing...it's some sort of reinforced PVC.   That's what they're using around here.
The ground rod is all we have.  And the power company's "ground rod."   Wink
We've decided to defer to an electrician.  Coming out this weekend to have a look and advise.   As Ed states, the requirements are ever changing, but I don't want to get too far out on "creative" wiring.  Afraid something (or someone) will fry.  Still gotta keep the place insured. 
Thanks for the input, JR

   
 
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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« Reply #8 on: March 14, 2007, 09:14:02 PM »

Great idea getting an electrician involved! Let us know what he says.
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Jim Stewart
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Moof
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« Reply #9 on: March 15, 2007, 07:35:28 AM »

I agree with the idea of getting an electrician involved.  What I have found over the years is that wiring is usually easy to do.  It works most of the time even when it is done wrong.

The statement that the electricians can't agree is true also.  I had to re-wire my circuit breaker panel a number of years ago because who ever wired it before I bought the house mixed the grounds and neutrals.  Hey it worked right?  The house I am in now needed some re-wiring.  When you opened the panel it looked right, but...  The panel and sub panel weren't bonded, ground went to the plumbing (not a well just a storage tank), and the neutral was tied into the ground in the wall.  I have since corrected those problems.

I was helping my brother upgrade his service in Minnesota.  He told me that his inspector didn't care if neutral and ground were mixed.  I talked to the inspector and he said it didn't matter.

Where I see the problem, in my simple brain, is that the ground and neutral each have a purpose.  Neutral completes the circuit and carries extra current away from the appliance.  When an appliance fails and it's chassis becomes hot, the ground carries that current away.  You can usually get a jolt from the neutral side of a hot circuit.  You shouldn't on the ground side if the appliance is working correctly.  By mixing grounds and neutrals you have juice going all over the place. 

But, I'm not an electrician, just a firefighter who puts out other peoples mistakes.  If I'm misguided here someone please enlighten me.

Dave T.
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« Reply #10 on: March 15, 2007, 11:55:20 AM »

Moof: I will try and enlighten you since you didn't believe the electrical inspector. At a service entrance panel (where power comes into the building from the meter) the ground wires and the neutral wires connect to the same bus bar which is bonded to the box and to ground (water pipe in municipal system or a ground rod).  BTW 300' of steel water well casing is a pretty good ground rod. You should never have any voltage on the neutral wire and never get a shock of the (neutral) white wire.

If you have a breaker panel which is a sub panel (not the service entrance) then you have two separate bus bars for neutral and ground.  They are not connected together and the neutral is not bonded to the panel, but go back to the service entrance panel as two separate wires (white and green [or bare]) where they both connect to the common bus bar.

The requirement being that there is only one common ground point.
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« Reply #11 on: March 15, 2007, 02:04:12 PM »

It seems pretty common in my neighborhood for the bare support wire from the pole to be used for the neutral when 1950's era houses were upgrading from 110 to 220 service. Not that that describes your situation exactly.

I don't suppose your 200' buried wire was in a conduit? If so, pulling more wire would be the answer, little or no digging required. I know codes have varied widely on burial requirements over the years.

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NJT5047
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« Reply #12 on: March 15, 2007, 07:04:03 PM »

The wiring to the out building is not in conduit.  The wiring was in the ground when I bought the place back in '86.  Two 4 ga (?) wires that resemble the stuff used for entrance service, but a little smaller.    I bought the home from one of the county electrical inspectors.   What he had worked great for 120...so now we get creative.  Whatever, the pump's working. 
I can tell you that there ain't no neutral, and there ain't no bond, beyond a ground rod.
I followed the neutral from the house service panel and noticed that the top wire on the power pole is same as the neutral.  The wire that's marked "white" is common to the top power pole wire, the transformer center and the guy wire....that's how I got the idea of using the power pole guy wire anchor (which is conveniently next to the out building) for a "neutral"...and it worked.  I don't really see a problem with this...other than the anchor isn't mine.  Same circuit as the neutral on the hose.  Sometimes what one doesn't "see" can be dangerous too.
I didn't leave the neutral hooked up for reasons such as maybe the building becomes a lightning arrestor..etc.   I expect the power company would take a rather negative view of using their equipment for neutral access.  Roll Eyes
Still, it works. 
I'm going to have to bury a neutral....it'll have to be hand dug...major bummer.. Angry   The ground rod will work for a bond, but the box is not correctly bonded (neutral and bond are combined in the sub panel), and very likely we are going to have to tear out whole damn sub-panel and wiring and start over.  That's the negative side these things.  Well, the water pump is working great.     
Best, JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
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« Reply #13 on: March 15, 2007, 08:22:53 PM »

I'm going to have to bury a neutral....it'll have to be hand dug...major bummer.. Angry   

Hand digging it 200' would really be a PIA.  If the electrical contractor does much underground cablnig he probably has a machine that cuts a slot in the ground to a predetermined depth and buries the cable all in one action.  I once saw a Comcast contractor bury a 75' run of cable 6" deep in about 15 minutes with one of them and barely distrubed the grass.

If not, I would probably go for renting a trencher before I hand dug it that far.  But that's just me.
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« Reply #14 on: March 16, 2007, 06:02:50 AM »

If cost is no object, one of the water jet machines would put a conduit of any size desired between the shed and house with just an entrance and exit hole the size of the conduit.

Certainly the the easiest and cheapest way is the transformer suggested by DrDave.  Depending on the size of the well pump, it might be easier to use a 120 volt primary to 240 volt secondary for the pump and run the shed the way it was originally designed with a ground rod for grounding.

I just looked in an old Grainger catalog and for a well pump in the 1 HP range, you would be less than $200.00 (smaller pump = less dollars). If you run the pump the way you have it connected now and just want 120 volts for lights in the shed the cost would be under $50.00.
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