# new underground service



## buffalo (May 2, 2015)

I'm digging a trench from the pole to my walkout basement , mounting the meter on the cmu's. code is 2' deep. is it a totally bad idea to use this trench for drainage also? Say I bury the wire with the clay I dug out , maybe 10" worth , then add a perferated pipe and stones?












I already dug drainage along the front of the house and it comes out by the stones on the right in the picture. So I want to keep water away from here . If I dig the trench another 8' it would empty into a small tributary to a creek.


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## CallMeVilla (May 2, 2015)

Just lazy or what?  Don't like digging a 24" trench twice?  Hehehehehe

I have collocated gas and electrical in the same trench.  Our code is 18" for gas and 11" for 110VAC.  No problem.  What are you using for your electrical service run?  Unless there is a code conflict, I don't see an issue here.


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## buffalo (May 2, 2015)

I don't believe there is any kind of code conflict , I'm just unsure if have drainage water above the line could create any kind of problems. I believe the wire I need is called URD , it's a 200 amp service wire For underground applications. Code is 24" deep , 18" if I put it in a conduit. I wouldn't mind a conduit but I don't think I could pull the wire through. It would require maybe four elbows and then I'm getting into expansion joints For the pvc also. 

Yes , I'm lazy , lol. This shovel has payed for itself many times over by now lol.


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## CallMeVilla (May 3, 2015)

WHY would anyone purposely choose to use aluminum underground?  URD is just not preferable to UF unless there is a max voltage problem.  

Regular type UF cable is available in most typical gauges but it is copper, not aluminum.  You can recognize UF cable because it generally has a gray or black sheathing.   You are probably wanting to use UF B Cable for Underground Burial.  This is the choice where the cable needs to be run underground without conduit.  Type UF B cable is made for direct burial underground without the use of conduit or other piping.  Type UF B cable is typically more expensive due to the different materials required to make the sheathing UV, moisture and temperature and corrosion resistant for underground applications.

The maximum voltage of all types of UF wire including UF and UF B are all the same. The maximum voltage set for each of these types of wiring is set at no more than 600 volts.

How does that work for you?


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## buffalo (May 4, 2015)

I'm just going by what the building inspector told me. I got a quote for underground wire and components from the supply house and they priced me URD also. I'm going to have to research this , thanks!


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## CallMeVilla (May 4, 2015)

From a cold climate friend ...  "I have been doing electrical work since 93 and have never used alum as a feeder or a service lateral.   We are in a colder climate, and due to the expanding and contracting of the material, all the guys that are in the know say its not practicle and even a little dangerous? Maybe its a wife's tale, but that is what I have heard. And I have seen a bit of wire. For anything underground, direct burrial, its always USE individual conductors, Copper. If its pulled in conduit and outside its always XHHW. We also use XHHW outside for all branch ckts. #12 and up. It wont crack in the cold. If you even try to pull a outside outlet out of a weatherproof enclosure at -30F wired with THHN, the thermoplastic can almost just explode off the copper.


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## buffalo (May 4, 2015)

Well I ended up calling my wife's uncle today. He worked for the power company before retiring and moving out of state. He told me to use the aluminum URD wire and encase in a 3"   conduit. He said it would not be a problem for me to peice the conduits this way ,  Now it's encased and I have nothing to worry about. The only downside is the corrosion with aluminum but you use the grease at the splices for this. Seems like every area has thier own way of doing things . But thatS what they seem to do here . The wire cost to go copper is crazy more with no real benefit to me. This will be a 4/0-4/0-2/0 wire.  Thank you for all the help.


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## nealtw (May 4, 2015)

Every house up here gets al. wire in conduit.


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## hornetd (May 5, 2015)

Check with the utility company engineering office for the service standards.  They may require a greater depth of bury than two feet.  They may also specify the fill you have to use around the conduit.  They will have a standard for the number of bends that are permissible.  The answers are all based on were the "Demarcation Point" is.  That is were your  service lateral starts and the utility's conductors end.  That is also were the rules of the National Electrical Safety Code; the code that applies to the utilities wiring; stop applying and the National Electrical Code's rules take over.  

I would suggest that you put the drainage beneath the electrical work.  

You have an opportunity to massively improve the resistance of your home to surge and spike damage coming in on utility wiring.  Run a number Two or larger American Wire Gauge, bare, copper conductor in the very lowest part of the trench for twenty four feet minimum length.  The drainage goes above this Grounding Electrode so as to provide the benefit of wetter soil around the Grounding Electrode Array.  At eight feet out from the building drive a ground rod through the bottom of the trench and clamp the #2 or larger conductor to it.  Drive another rod at twice the length of the rods apart.  For best effect that Grounding Electrode wire should be at least thirty inches deep and three feet of more is better.  If that number two wire were encircling the house it would be called a ground ring but running it in the service trench does not lessen it's effectiveness.  The house end of the Grounding Electrode Conductor terminates on the Neutral buss of the Service Equipment Enclosure.  

-- 
Tom Horne


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## WyrTwister (May 10, 2015)

I know practices vary regionally .

     I would run PVC conduit and copper wire , individual THHN / THWN .

     NEC requires 24" deep .  Local codes vary .

     What is the distance on the service ?

God bless
Wyr


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## hornetd (May 11, 2015)

WyrTwister said:


> I know practices vary regionally .
> 
> I would run PVC conduit and copper wire , individual THHN / THWN .
> 
> ...



Wyr  

It is important to know were the state utility regulatory agency has set the Demarcation Point.  That is the point were the National Electric Code begins and the National Electrical Safety Code ceases to apply.  Underground service conductors which run without any splice from the utility transformer or low lines to the structure are often under the National Electrical Safety Code for the entire run with the Demarcation Point being the the Meter Enclosure.  If that is true here then the depth of burial, requirements for conduit type and number of bends, and even the fill material and it's depth above and below the raceway, will be laid out in the utilities installation standard as tariffed; i.e. accepted by the utility regulator.  Utility installation standards often call for service conductors to be installed in Heavy walled conduit such as schedule eighty PVC.  The depth of bury could be three feet or more.  The installation standard may require a particular type of fill in place of some of what was removed when the trench was excavated.  If the OP does not confirm which rules will apply then he may be in for a rude surprise when the utility shows up to do their portion of the work.  

-- 
Tom Horne


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## buffalo (May 13, 2015)

Electrical inspector stopped out today . I'm all set. Have to call the power company tomarrow and schedule the switch over.


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## nealtw (May 13, 2015)

Looks good, good job.


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## hornetd (May 13, 2015)

Now is the time to make the intimate acquaintance of the National Institute of Standards and Technology document  NIST SPECIAL PUBLICATION SP 960-6.  It is titled "SURGES HAPPEN! How to protect the appliances in your home."  Since you are serving as your own electrical contractor read that section very carefully.  

Most important is that before you back-fill the trench you should decide whether your existing grounding electrode system is adequate.  If you have a metal water service lateral that is connected to a metal pipe water distribution system and that has been connected to the neutral conductor of the Electrical Service Equipment, as required by the National Electric Code, your probably set as long as that piping is continuous and free of insulating connecters.  

If you are unsure of the quality of your Grounding Electrode System you have a great opportunity to improve it by installing Twenty Four feet of large bare copper wire no smaller than number Two American Wire Gauge (2AWG) in the bottom of the trench and driving two ground rods through the bottom of the trench that you will then connect the bare copper conductor to.  The first rod is driven it's own length away from the foundation of the home to assure that it has a full shell of earth around it in all directions.  The second rod is driven twice the length of the rod away from the first.  With the usual eight foot rods that would be sixteen feet further out in the trench hence the total of twenty four feet of conductor in the bottom of the trench.  The bare conductor needs to be long enough to be brought into the Service Equipment Enclosure and connected to the neutral buss bar.  That will give you a pretty good grounding electrode system without a great deal of additional effort.

If you do end up putting drainage piping into the same trench; since you did mention that possibility; you should use the perforated piping for the portion adjacent to the Grounding Electrode Conductor so as to keep the soil around the Grounding Electrode System as moist as practical.  

You will never have another chance to install an effective Grounding Electrode System with as little work as while you have that trench open.  

-- 
Tom Horne


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## buffalo (May 13, 2015)

Thx hornetd. I had to drive two 8' rods into the ground 6' apart , probably can't see in the pics. thier in the trench. Tie a bare ground from the main panel to them . Also a ground to my water and gas pipes. That was code . The existing panel , so to be a subpanel , also has this as it was done 2 years ago. 
  There are some issues with gararage and an outbuilding I will have to get to. Only a 3 wire feeds them.


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## buffalo (May 13, 2015)

nealtw said:


> Looks good, good job.



Thx bud! I Ended up underpinning that pad while I was there , thx for that video a while back:beer:. Also repointed the whole wall. It was a mess.


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## nealtw (May 13, 2015)

What did the inspector say about your old ground rods. As I understand it, they should not be there. The sub should be grounded at the main.


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## buffalo (May 13, 2015)

He never said to disconnect them. I'll ask him when the switchover happens.


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## hornetd (May 14, 2015)

buffalo said:


> Thx hornetd. I had to drive two 8' rods into the ground 6' apart , probably can't see in the pics. thier in the trench. Tie a bare ground from the main panel to them . Also a ground to my water and gas pipes. That was code . The existing panel , so to be a subpanel , also has this as it was done 2 years ago.
> There are some issues with gararage and an outbuilding I will have to get to. Only a 3 wire feeds them.



I did notice the code required Grounding Electrode Conductor coming out of the basement in one of your earlier pictures.  What I was trying to suggest is that you do more than the code required minimum while you still have the opportunity.  The Grounding Electrode System (GES) that is required by the National Electric Code (NEC) is the minimum necessary for electrical safety.  Section 90.1 of the NEC makes that very clear.  

"90.1 Purpose
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity. This Code is not intended as a design specification or an instruction manual for untrained persons."  

That means that if you comply with the provisions of the NEC you are unlikely to electrocute yourself or anyone else and you are unlikely to cause a fire of electrical origin.  It does not mean that the grounding is adequate to markedly reduce the chances of surge damage to your electronic devices and appliances.  

Even Gas Ranges have microprocessor controls.  A surge event can cost you hundreds of dollars in damaged equipment.  Proving that the surge originated on a particular utilities wiring can be very difficult.  The question then becomes who pays.  If it is lightning that struck your home your home owners insurance may have to pay the losses but many such policies include low limits on how much will be paid for electronics.  If it is lightning or a switching surge on the power utility's  system; and you can somehow prove that; then the utility has to cover the loss.  You don't want to end up caught between the various actors with each pointing the finger at each other. 

That is why the National Institute for Standards and Technology (NIST) wrote the document that I referred you to earlier.  It is free and you can download it in a PDF file format.  Installing the better ground system is easy to do while the trench is still open but would be a lot of work later.  Take the time to look at the "Surges Happen" booklet from NIST and don't miss your present opportunity.  I have a Ground loop impedance tester in my testing tool arsenal.  I have measured many code compliant Grounding Electrode Systems that had impedance values over a hundred ohms.  That is far too high for surge and spike protection.  If you install the Number Two AWG wire and one more ground rod which is two rod lengths away from the nearest of the other two then you will lower your GES's impedance markedly.  It is that low impedance to earth that permits your Service Equipment Surge Protector to work most effectively.  

*You were planning to install a whole house surge protector as NIST recommends weren't you? *

I have comments about your old Service Equipment in another posting.  I have been working as an electrician for over Thirty years so I have been down the road you are traveling several times.  I am only trying to point out the sharp curves and axle busting pot holes that I found the hard way.  There is a great fire house axiom that says "Good judgement comes with experience.  Experience comes with bad judgement."  FWIW YMWV

-- 
Tom Horne


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## hornetd (May 14, 2015)

nealtw said:


> What did the inspector say about your old ground rods. As I understand it, they should not be there. The sub should be grounded at the main.



The National Electric Code Does not forbid the presence of what it calls Supplemental Grounding Electrodes as long as they are only bonded to the Equipment Grounding Conductor (EGC) and not to the Grounded Current Carrying Conductor; which most of us call the neutral.  

In the process of converting the old service equipment to a lighting and appliance panel-board he will have to install separate Equipment Grounding Conductor (EGC) buss bar or bars and remove the main bonding jumper which bonds the neutral buss bar to the panel-board enclosure.  He will then have to move all of the EGCs to the new buss bar/s.  

The last step is to disconnect the Neutral of the feeder from the Neutral buss in the converted panel and test that no short circuit or sneak current path exist between the Feeder Supplied Panel's (Sub Panel's) Neutral and the cabinet that encloses that panel as well as to the Equipment Grounding Conductors which are terminated in that enclosure which, even after the removal of the main bonding jumper, will be bonded to the enclosure.  The EGC buss bar/s that are added to the enclosure are bonded to the enclosure by their mounting hardware which has been tested to perform that function.

A Grounding Electrode System is required to be installed just that way at outbuildings that are supplied from the same service when the feeder is installed under the present day code.  Earlier editions of the code allowed a feeder with no separate equipment grounding conductor and the neutral conductor grounded again at each outbuilding.  Experience has shown that bonding the neutral to the building disconnecting means and thus to the Equipment Grounding Conductor buss bar/s at outbuildings that are supplied from the same service will cause neutral current to flow on any conductive path between the buildings that are served by the same electrical service.  Such pathways can be metal water piping, conductive fuel gas piping, telephone lines, coaxial cables for television or internet, communications wiring, and the list goes on.  The danger that can result is that if any open or break were to occur in the neutral conductor of the outbuilding's feeder circuit the neutral current uses all surviving conductive pathways to return to it's source at the electric utility's transformer.  Since those pathways were not intended to carry current the voltage drop that occurs over these unintended pathways will raise the touch potential of exposed conductive surfaces in the outbuilding to dangerous levels.  

-- 
Tom Horne


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