200A Service, disconnect, and wire sizing

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  #1  
Old 09-29-06, 07:16 PM
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Question 200A Service, disconnect, and wire sizing

I have read many of the threads on the subject, but I would appreciate some validation of what I am attempting to do.

This is a new construction, 1650 s.f.. The home layout is basically this:
The meter/disconnect, 220A with main breaker (planned), will have underground service at the north end of the house. The load center, 200A (no main), will be in the garage, near the opposite end of the house (approx. 35'). The bonding rod to the rebar in the slab foundation is 10' further from the load panel or approx. 45' from the service entrance. This rebar bonding placement was the result of a plan that changed during construction.

Questions:

1) It sounds like every c-b panel becomes a sub-panel if it is beyond the main breaker? It also appears that the service entrance has to have a disconnect or main breaker. This then would make every load center a sub-panel?

2) If my panel has to be treated as a sub-panel (bonding the ground and isolating the neutral), then I need a bare ground that runs back to the service panel and ground rod? With a second bonding source required, can I continue the bond wire from the service panel to the load center and then to the rebar bond 10' away?

3) Will 3/0 cu be best, with a margin of error to the safe side, or is 2/0 a safe conductor size? Is #4 cu the proper bare ground?

4) Is there a need or advantage to having a main breaker at the meter and a main in the load center panel?

Thanks,
 
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Old 09-29-06, 07:31 PM
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Single family home?

200 Amp service? 3/0 Copper. your house? spend it.
(I bought my son a cheap bike, It didn't last) So I bought another one. What did I save?

Service drop to the meter/ main breaker there. Ground rod, to meter neutral, and a ground (same unspliced conductor)to the water meter and jumped around the meter ( line and load of water).

EVERY PANEL AFTER THIS "main" Shall be treated as a "Sub".
 
  #3  
Old 09-29-06, 08:16 PM
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Yes it is single family residence that I am building.
There is no water line or meter to tie to. It is a deep well, and all plumbing is cpvc.

I had planned for the rebar "bond" to the foundation rebar to be the second ground source (std. for the building dept. here in NW Florida).

Do I have this straight?

One ground wire (unspliced) from ground rod to neutral of meter and to ground in service panel, then to a second ground source? All unspliced of course.

Better planning would have put my service at the other end of the house or the rebar at the service end, but unfortunately it is not the case and is not an option now.

Can I continue this same bare copper to the rebar approx. 35-40' away. Any other suggestions or cheaper options for the second ground, since I have cpvc plumbing?

I am not looking to toss away $$'s, but certainly I want to do it right, and with safety margins.

Thanks for help
 
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Old 09-29-06, 08:36 PM
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@I had planned for the rebar "bond" to the foundation rebar to be the second ground source (std. for the building dept. here in NW Florida)[email protected]

Just a day ago there was a discusion about this,(UFER Ground).
This was new to me (google it, Cool) but appears to be what your thinking of.
This is used in very dry enviroments. I won't go on, others who may know more will. In the North East, no shortage of water or earth. I digress, Sorry.

Any event, Your building/earth ground should be bonded with the neutral wire from the service entrance. This ties to your electric meter. From the elec meter to a box with a main breaker.
3 wires and ground.

From this main breaker enclosure, EVERYTHING else is considerd a "SUB PANEL". And should be treated as such.

Your service entrance can come from any end of the house. Put the meter, ground and main disconnect at the point nearest the power co., Then run a 4/wire se cable from main disco to the main panel.
 
  #5  
Old 09-29-06, 09:13 PM
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Originally Posted by lectriclee
Your service entrance can come from any end of the house. Put the meter, ground and main disconnect at the point nearest the power co., Then run a 4/wire se cable from main disco to the main panel.
This is the situation I have, but isn't a second earth ground required? Can that second ground be the rebar? Is the fact the two earth grounds are 35 feet apart an issue?

I was figuring the (3) 3/0 cu from the service disconnect and #4 cu bare ground, to the main panel. I am assuming this has to run in conduit? Is the 4/wire se cable, just that, a cable and acceptable without conduit? Sorry, I have to plead ignorance there.

Thanks
 
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Old 09-29-06, 09:33 PM
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In your jurisdiction, there may be other codes. Plastic water pipes, again your jurisdiction. Ask the local authority.

It gets COLD (damn) so our water feeds are copper.

My advice is general is based on NATIONAL standards. Your local may be differrent, ours is.

SE cable inside the dwelling does not need conduit. so long as it is NOT subject to physical damage.

The ground rod is for ground and to insure the neutral is grounded,There should be only 1 referance to ground per service entrance. the jumper to the water main is to bond the pipes. RE; Supplimental ground, That may be an FLA. Rule. again check with the locals.
 
  #7  
Old 09-30-06, 05:41 AM
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The local here has told me that they use the 2005 NEC, without modification or revision.

I thought that I had read someplace on the forum that a supplemental or second ground was required and that it be tied without any cuts or splices. It sounds like the second ground isn't required, true?

Hate to keep wipping the dead horse, but I want to get it right. When the inspector came out to inspect my foundation prep he said, "where is your rebar bond", so I feel certain that he will be looking for the tie to that foundation steel.

Your input is appreciated, and as suggested I will ask about what they may expect the rebar (UFER ground) to tie to.


thanks
 
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Old 09-30-06, 06:01 AM
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3) 2/0 CU is ABSOLUTELY fine. Unless the secondary side feeding the service is 200'+ there is no need to upsize.

2) Under NEC 2005, there is no, repeat NO supplemental grounding electrode required when using a UFER as the primary electrode and no metallic water pipe present. ONLY a metallic water pipe electrode requires a supplemental electrode.
We get VERY cold here as well, but most of our water feeds come from wells like the OP and this typically means plastic feeding the house.
Temperature has nothing to do with it. Typically: municipal water = copper. Well = plastic.




"The ground rod is for ground and to insure the neutral is grounded,There should be only 1 referance to ground per service entrance."

Lee, I am not trying to start a war, but this is completely incorrect. The ground rod is not "for ground" and does NOT ground anything.
Also, can you elaborate and provide a code refrence about the "1 referance to ground" you mentioned?
 
  #9  
Old 09-30-06, 12:57 PM
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wow here , in this jurisdiction the meter is never grounded, The nuetral floats inside the can
 
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Old 09-30-06, 03:56 PM
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Speedy,
I Install a ground rod why?
To provide a referance for the power co.. In case theirs fail. I will provide the grounded coductor.

Code Reference;NO. I must find more time to read.

Single reference to ground:
Would you add a ground rod to a sub panel (attached)? Your ground is the ground. If electrodes were added at remote locations, would that be safe?

Water meter; Correct, temp has nothing to do with it.
Well or municipality, The copper must be bonded.
The reasoning here, jumping the water meter, Is, if the meter fails, you still have a bond to the lines.

William, What meter? Electric? You never send the ground to the neutral at the meter or main panel? Or water, You never bond the pipes?
 
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Old 09-30-06, 07:07 PM
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"To provide a referance for the power co.. In case theirs fail. I will provide the grounded coductor."

If the POCO neutral (grounded conductor) fails, your ground rod ABSOLUTELY will not "provide" a ground or neutral.

http://www.mikeholt.com/technical.php?id=grounding/unformatted/Groundrodfault&type=u&title=Ground%20Rod%20Does%20Not%20Assist%20in%20Clearing%20a%20Fault%20(01-25-2K)
http://www.mikeholt.com/technical.php?id=grounding/unformatted/Groundrodtouch&type=u&title=Ground%20Rod%20Does%20Not%20Reduce%20Touch%20Potential%20(01-25-2K)%20
http://www.mikeholt.com/technical.php?id=grounding/unformatted/metalpoles&type=u&title=Ground%20Rod%20at%20Metal%20Poles%20a%20Waste?%20(8-5-2K)
 
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Old 09-30-06, 07:16 PM
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so The POCO, looses A neutral, What does my ground do?

does it not pick up the slack?
 
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Old 09-30-06, 07:49 PM
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Okay, let me replay what I think my ears heard.

For my setup:

A ground for the service disconnect. The ground runs to the neutral of the meter. In the service breaker box (at the meter), the neutral from the meter is tied to the ground bar of the disco?

Since there is no cu water pipes involved that completes the service panel except for running conductors to the main panel (sub-panel) in the garage?

For the main panel, depending on how I want to spend $$'s, I can run 3 conductors of 2/0 cu or 3/0 cu, plus a ground of #4 bare cu? This requires conduit correct?

The bare #4 copper will be tied to the grounding bar at the main disco and then tied to and only to the ground bar at the main panel in the garage? The neutral in the main panel (sub-panel) in the garage will and must be isolated from the grounding bar?

My new slant on the question of the rebar (UFER ground) and since I have to run a ground the width of the house anyway; can I run my ground from the rebar to the grounding bar in the garage panel (without any splices or breaks) and continue the run to the main disco? I am thinking the normal path is; ground rod to meter neutral, meter neutral to disco ground, disco ground to main panel ground bar. Can I reverse the starting point for the ground if I have no splices, and go UFER to main panel ground, main panel ground to disco ground bar, disco ground to meter neutral? This would eliminate me having to drive a ground rod at the service entrance. Yea, I can afford the rod, I'm just not real fond of my sledge hammer work.

Thanks
 
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Old 09-30-06, 08:02 PM
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"so The POCO, looses A neutral, What does my ground do?

does it not pick up the slack?"


NO. It does not.
 
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Old 09-30-06, 08:03 PM
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I'm not sure if you cared to read the links I quoted, but this one is key. You should read it.

http://www.mikeholt.com/technical.php?id=grounding/unformatted/Groundrodfault&type=u&title=Ground%20Rod%20Does%20Not%20Assist%20in%20Clearing%20a%20Fault%20(01-25-2K)
 
  #16  
Old 09-30-06, 08:30 PM
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Okay, thanks, I will. The reference post wasn't there when I was typing my long winded questions.

I need to talk to my local inspector about the rebar (UFER). I have a real hunch from the pre-foundation inspection comments that they will be looking for the supplemental ground (rebar). I think he made a comment about continuing the ground rod to the UFER, when he was assuming my service would originally have been about 10 or so feet away from the rebar. It is a must that I talk to him to see what his thinking is, he referred to the rebar as my "bond". So, he could thinking of bonding the plumbing, so, to put the uncertainty to rest I will ask him.

But, if I tie the rebar and the service ground haven't I violated the rule of only one ground for the service?

This forum is great, and the time that you fellows devote to it and to people like myself, is huge public service. Thank you all.
 
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Old 09-30-06, 08:42 PM
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Smile

Ramiron; thanks we all try.

Speedy; I'll check the site, thanks. I'm better with the tools, than this box. (techno phobe? Thats me).
 
  #18  
Old 10-01-06, 03:44 AM
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"But, if I tie the rebar and the service ground haven't I violated the rule of only one ground for the service?"

What the code says is that all of the required grounding electrodes need to be bonded together to form the grounding electrode system. The rule is not that we only have one grounding electrode, it is that we bond all of the electrodes to make them act as one system.

Also check with the inspector before you run one of the electrodes wire to a sub panel instead of the main panel. IMHO this is not OK. If the panel location has moved, then you will need to run one continouse conductor from the electrode (rebar, rod, waterpipe etc) back to the main panel location.

I hope this helps.
 
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Old 10-01-06, 06:46 AM
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Ram,
The UFER is not a supplemental electrode if there is no metallic water pipe electrode in the house. If there is a metallic water pipe feeding the house then the UFER can be the supplemental electrode.

Like I said before, when using a UFER alone, NO supplemental electrode is required. The inspector can ask for one but he is wrong.
 
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Old 10-01-06, 08:36 AM
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Thumbs up

Now I think you guys have explained this every way possible and it is beginning so sink in.

Embarassing, but someone local also suggested what I have been thinking as "not an option", as actually being an option. That is, locating the service on the opposite end of the house. Even with power pole, septic drain field, etc., making the route somewhat indirect, it MAY be the most economical, and DEFINATELY the most convenient. It boils down to the street to house run will be about the same whether at the north or south end of the house. The difference will be that instead of me going north to south in the attic with 3/0 CU, the POCO will go north to south along the property line with direct bury AL.

Then the service will be near the sub panel (12-15'). Now it would be an easy matter of bonding the UFER and a ground rod, and running to the meter neutral, then taking my main breaker ground to the sub panel ground bar.

Does this sound right? It sure is sounding better to me.
Sorry to take so much of your time and beat this to death, but it sure has been an eye opener. Thanks. Oh yea, Pete I read the UFER articles, good/more education.
 
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Old 10-01-06, 10:02 AM
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If you are talking about bringing your ufer and all other grounding electrodes to the main service disconnect, then running a XX-3 w/g cable to the sub panel. Yes I like it.
 
  #22  
Old 10-01-06, 05:47 PM
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Thumbs up

Yes, JWHITE, that is the plan, if the POCO isn't extremely expensive for their extra run. But at any rate, I am thinking they will be as cheap or cheaper than I could make the attic run for.

Just cleaning this install up, by the better location of the main HAS to add a lot of value in my mind. Besides, the main service disconnect (with main & 8 breaker slots) would be close to the outside A/C unit for easy connecting, and the well is also on that same end of the house, so another circuit that could stay outside and off the sub-panel.

Thanks again guys for all your help, you have been most generous with your knowledge throughout my whole construction project.
 
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