# Help with sizing parallel conductors



## Cletis (Aug 20, 2010)

250mcm ungrounded, 4/0's grounded

no


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## wildleg (Apr 12, 2009)

you can do your own house service without an electrical license ? (in my area you can do the wiring, but I don't think homeowners can do the service?)
250kcmil AL


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## Dennis Alwon (May 9, 2009)

I would look at 225.30 before you do that install. They are not parallel conductors if they are not connected at both ends. You are feeding the house with 2 feeders and that is a violation.


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## bkmichael65 (Mar 25, 2013)

...........


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## bkmichael65 (Mar 25, 2013)

I just noticed something about 2 disconnects. What's up with that?


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## Dennis Alwon (May 9, 2009)

bkmichael65 said:


> I just noticed something about 2 disconnects. What's up with that?


Read my post


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## bkmichael65 (Mar 25, 2013)

Dennis Alwon said:


> Read my post


So, he's not talking about parallel conductors then. He better go back to the drawing board


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## 8V71 (Dec 23, 2011)

Dennis Alwon said:


> I would look at 225.30 before you do that install. They are not parallel conductors if they are not connected at both ends. You are feeding the house with 2 feeders and that is a violation.


You would be code compliant with one 400 amp disconnect. Then you could run single or parallel if you wish and tap off to both panels in a jbox or trough following the tap rules.


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## Deep Cover (Dec 8, 2012)

> 2. Do I need a grounding conductor from the "rack" to the house ( as far as I know the the rebar in the slabs are connected to the GEC at the house ). I have not looked at the electric utility pedestal at this time so I am unsure in there is a GEC located there.


Yes, you would need a grounding conductor to the house. Ignore Cletis.


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## backstay (Feb 3, 2011)

Deep Cover said:


> Yes, you would need a grounding conductor to the house. Ignore Cletis.


What kind of disconnect, if you don't have an OCP, then 3 wire and no grounding connector. If rebar in the slab, then no ground rods either.


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## Dennis Alwon (May 9, 2009)

backstay said:


> If rebar in the slab, then no ground rods either.


Not sure you meant slab but rebar in the slab is not a grounding electrode. It must be in the footing


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## backstay (Feb 3, 2011)

Dennis Alwon said:


> Not sure you meant slab but rebar in the slab is not a grounding electrode. It must be in the footing


Yes, in the footing in direct contact with the earth. Most of our slabs are monolithic.


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## 8V71 (Dec 23, 2011)

backstay said:


> What kind of disconnect, if you don't have an OCP, then 3 wire and no grounding connector.


Interesting....:stuart:

We need a code head spinning emoticon.


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## Tjpgi (Aug 27, 2013)

Many of the homes in the subdivision have 200 amp services with one disconnect at the pedestal. Some of the larger homes have 2 separate disconnects at the pedestal and each with its own separate conduit leading to the house. Within the houses are 2 separate distribution panels each with a 200 amp main breaker. 

On this link from the electric utility company, under "Download Metering Specifications", you can see how they diagram their rack system. 
http://www.pec.coop/Home/BuildersContractors.aspx

Ah..agreed... parallel conductors poor choice of terminology on my part. 

As stated above these are monolithic slabs without footings and the bedrock is actually at the surface in many areas of this part of Texas. The grounding electrode is placed in the slab per 250.52(3) specifications is what I think the electricians are using because of the difficulty in driving ground rods into the soil .

I'll contact the design folks at Pedernales prior to starting any installations.

Thanks to all


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## backstay (Feb 3, 2011)

Tjpgi said:


> Many of the homes in the subdivision have 200 amp services with one disconnect at the pedestal. Some of the larger homes have 2 separate disconnects at the pedestal and each with its own separate conduit leading to the house. Within the houses are 2 separate distribution panels each with a 200 amp main breaker.
> 
> On this link from the electric utility company, under "Download Metering Specifications", you can see how they diagram their rack system.
> http://www.pec.coop/Home/BuildersContractors.aspx
> ...


Two discos at the house is a violation, IMO.


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## hardworkingstiff (Jan 22, 2007)

Tjpgi said:


> I'll contact the design folks at Pedernales prior to starting any installations.


I'd talk to the AHJ, they will make the final decision.


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## gleeming (May 24, 2009)

backstay said:


> Two discos at the house is a violation, IMO.


Not if they are sub-panels with 4-wire feeding them and unbonded N and G


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## backstay (Feb 3, 2011)

gleeming said:


> Not if they are sub-panels with 4-wire feeding them and unbonded N and G


I believe you are not correct. NEC still considers the 4 wire feed as a service to the house. And you can only have one.


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## Bbsound (Dec 16, 2011)

Dennis Alwon said:


> Not sure you meant slab but rebar in the slab is not a grounding electrode. It must be in the footing


That is a questionable statement. Code says "concrete foundation or footing"

I say the slab is foundation.


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## Going_Commando (Oct 1, 2011)

Bbsound said:


> That is a questionable statement. Code says "concrete foundation or footing"
> 
> I say the slab is foundation.


A house will still stand without a slab, but won't without a foundation. Tricky eh? :whistling2:

It was my understanding that if you have a 320A rated meter, you could do 2-200A panels off of it. Neither would be a main power feeder, they would just be feeders. Is that wrong?


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## BBQ (Nov 16, 2010)

Bbsound said:


> That is a questionable statement. Code says "concrete foundation or footing"
> 
> I say the slab is foundation.


Most slabs are not foundations.

It is not up to us decide, it is spelled out in the building codes.


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## varmit (Apr 19, 2009)

My interpretation on this: The "rack" at the property line would be the service. The two disconnects, at the rack, would be the service disconnects. The two panels, in the house, would be sub panels. The circuits from each disconnect, to each panel, would require four conductors- 2 hots, 1 neutral, and 1 bonding conductor. Depending on your local AHJ, you will probably need to run a conductor from the ufer ground to the service rack and bond all of the bonding conductors and the grounded conductors (neutrals) together.

Of course, residential service local codes seem to vary from place to place more than any other codes, so please check with your local utility or inspection agency.


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## Shockdoc (Mar 4, 2010)

Method we have always used for 400 out here is two 4/0s triplexes from remote trns s cabinet to two 200 amp panels. Are you telling me this is no longer code?


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## Tjpgi (Aug 27, 2013)

varmit said:


> My interpretation on this: The "rack" at the property line would be the service. The two disconnects, at the rack, would be the service disconnects. The two panels, in the house, would be sub panels. The circuits from each disconnect, to each panel, would require four conductors- 2 hots, 1 neutral, and 1 bonding conductor. Depending on your local AHJ, you will probably need to run a conductor from the ufer ground to the service rack and bond all of the bonding conductors and the grounded conductors (neutrals) together.
> 
> Of course, residential service local codes seem to vary from place to place more than any other codes, so please check with your local utility or inspection agency.


This subdivision is in an unincorporated part of Comal County, TX. and does not require a building permit or other building inspections. The only inspections required for the site are septic and access over county ROW. Other than agricultural regulations, I have never come across this before. The houses in the subdivision are quite upscale but apparently ( according to realtors I have spoken with and several builders there have been few problems). I have a reputable contractor that I am comfortable with and plan on hiring an electrical, plumbing and HVAC inspecotrs to check the work. I have no lack of confidence in the EC here, I just want the flexibility and pride in wiring my house (take the savings and spend it on upgrades to the kitchen for my bride of 44 years).

I wired my 3600 square foot, 2 story multi purpose building in Ohio a few years ago and met with the county electrical inspector on site to go over what I planned and what he would recommend that I do to meet code.

I thought the way things were done here regarding the service was unusual and it appears many of you guys do too.

Thanks for all of the suggestions. I'll talk to Pedernales and post their recommendations.


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## varmit (Apr 19, 2009)

Shockdoc said:


> Method we have always used for 400 out here is two 4/0s triplexes from remote trns s cabinet to two 200 amp panels. Are you telling me this is no longer code?


From xfmr. to service panel would be code compliant. The OP states that at his location a disconnect is required at the property boundary. So the cable from this disconnect, to the panel(s) in the house would be sub feeds not service conductors. As always, the local AHJ may see things differently.


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## Bbsound (Dec 16, 2011)

Going_Commando said:


> A house will still stand without a slab, but won't without a foundation. Tricky eh? :whistling2:


not the interior walls


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## Dennis Alwon (May 9, 2009)

Shockdoc said:


> Method we have always used for 400 out here is two 4/0s triplexes from remote trns s cabinet to two 200 amp panels. Are you telling me this is no longer code?


It has not been code to run 2 feeders to a structure - with few exceptions. Once the 2 runs of triplex are split they are no longer a parallel run and thus you have two feeders as the op stated. You could run 2- runs and terminate them in a trough and then feed the 2- 200 panels.


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## Shockdoc (Mar 4, 2010)

Dennis Alwon said:


> It has not been code to run 2 feeders to a structure - with few exceptions. Once the 2 runs of triplex are split they are no longer a parallel run and thus you have two feeders as the op stated. You could run 2- runs and terminate them in a trough and then feed the 2- 200 panels.


Must be something local AHJ tend to overlook. I have yet to see a 400 amp dual 200 panel install out here with the conductors bugged together at the main breaker end. I as well partook in many of these installs thru out the 90's.


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## TUNIT (Sep 18, 2013)

Tjpgi said:


> I held a master electrician's license in the 1970's and concentrated mainly on residential wiring back then. I switched careers and have been way from contracting for a long while. I am going to build a new house in the near future (currently on the drawing board) and will be doing the electrical wiring. I have purchased 2011 NEC Charles Miller Residential Electrical Installations (abbreviated code book) and have been religiously studying the code. I also have one of Mike Holt's books ordered.
> 
> 
> The utility company in Spring Branch, Texas requires a "rack system" at the property line at the street. (a pedestal, 3" rigid nipple from pedestal to meter socket, and a 2" rigid nipple(s) from meter socket to either one or 2 disconnects) which is quite different from what I was used to back in the 70's.
> ...


Hey boss 300 aluminum is good for 230A,and think that would cover any voltage drop,if you have any on service from power co,but my question is why cant you run one 4" pipe with the 8 300's and one disc,with parellel lugs and a 400 amp panel at the house,which i guess i have always seen two 200's but you should still be able to get one 400A disc at the street with parellel lugs and maybe same at the house and then load side to two 200's.Sorry should have thought before i wrote you but one at the power co,400A disc and one at the house with one 4" in between and both runs in it,you can get 11 300's in a 4" and then at the house hit your 2 200's from load on the 400,i know here in florida you could get those disconnects with parrelel lugs,i am pretty sure.Let me know if that helped.Good luck


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## ralph (Apr 6, 2008)

I don't think your too far off. The service is at the ( rack), which is going to have 2- 200 amp breakers fed from the 400 amp meter socket. 2-ungrounded conductors of maybe 4/0 al and one grounded conductor of maybe 2/0 al to the line side of each disconnect. Then, from each disconnect to panels in the house with 4 - conductors.
I would make sure that the upher ground made it from the footing to the " rack".
Also, how are you getting into the house ? conduit under slab, or coming up and cabeling into the house ? You might need gound rods and additional disconnects at the house. Also proper identification at the service of each disconnect . You only have one service, so this install should be ok. Also, from the load side of the breaker to each panel, 300 al and a 4/0 neutral should be fine along with a grounding conductor


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