# Running power to my first shop - triplex or quadruplex?



## mcg1990 (Nov 11, 2014)

Hi all,

After multiple forum posts on the issue, then settling, then getting new information on it, I'm once again dumbfounded on how to run power to my shop.

Quickfire stats: Running ~70ft cable direct buried from 200A panel to 100A subpanel in a detached shop (300sqft). No pipes/wires in between the two structures. Using #2 Aluminum, so putting in a 90A (or 100A?) breaker in the panel back up at the house. Interior shop wiring features multiple 120V and 240V circuits. I'm quite future proofed and have wired for the following: dedicated circuit for dust collection, dedicated circuit for air compressor, multiple outlets pigtailed and dotted around just in case - tools hooked up to these would never be used at the same time.

So the question: 2-2-4 aluminum, or 2-2-2-4?

I believe I understand that quadplex is the 'correct' way, but this work is not being inspected. I want it to work, and don't want to kill myself and/or others, but I really need some pragmatic advice here - not just "do it by the code" - because my electrician says 2-2-4 will suffice. I need to know if he's saying that because he's been there done that and it's good enough, or because he's a cowboy who wants to use what Home Depot sell 20 minutes away.

Thanks all


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## wapakfred (Jul 29, 2011)

It sounds like you know what the code indicates. But I'll tell, I live in an incorporated area (no inspection) and my electric provider (a co-op) told to run the 2-2-4. Then, when we moved 5 years ago, I had the current shop wired by local electricians (both shops were a 100 amp sub panel). He ran 2-2-4 to it. This was also approved (again, no inspection….they just happened to be here during the work) but the provider, this tine it was the village I live near that has municipal power. You won't kill your self, and it works just fine.


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## daddywoofdawg (Feb 1, 2014)

My dad was a sparky for 40 years;he had always said no to Using Aluminum.


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## BoardSMITH (Mar 15, 2012)

Hire a licensed electrician! If you screw up the install in any way a fire might destroy everything and you will have to deal with your insurance company. Hiring a licensed and experienced electrician will cost a little bit more but if anything goes wrong, you and your insurance company can go after the company you hired.


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## dozer57 (Apr 18, 2014)

+1 on licensed electrician
If you do it yourself you only need triplex wire, quadplex is for 3 phase power. If you don't have any tools that require 3 phase power triplex should work fine. one thing be sure to bury it deep enough and make sure backfill has no sharp rocks in it. 70 foot run to your shop is not that far, if it was me i would put it in plastic conduit. no power leaks to earth ground and insulation on wire will last, the covering on the wire is not very thick. I learned this from exp. cost me way more in power draining to ground and had to replace it all. good luck


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## Clouseau (Feb 4, 2010)

I would definitely run it in plastic conduit. While you at it, you might want to run another conduit with wire for low voltage light switch,phone, intercom or cable. I know all this stuff is going wireless, but it's difficult to predict what you might want/need in the future. You could even use plastic water line. My concrete contractor thought I was a pain with all the plastic nipples and under concrete conduit, but I ended up using every one. Put the line/rope in while you lay it, and pull another line anytime you that one through. That will eliminate fishing.
Dan Coleman


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## EEngineer (Jul 4, 2008)

+1 on licensed electrician.

But you already know the answer. You mentioned it yourself in the original post. And it has nothing to do with 3-phase. Now let's talk why…

In the US, 220V power is actually 2 X 110V legs 180 degrees out of phase. 220V loads do not cause any currents in the Neutral leg. As a matter of fact, equivalent loads on both 110V legs will not cause current in the neutral line since the neutral currents from both legs are out of phase and cancel. But, if the full capacity of the feeder is used on only 1 X 110V leg, then the neutral line must be able to carry the entire return current and should be the same size.

There are also grounding issues. This is a feeder to a subpanel in a detached building and NEC requires a separate ground run from the main panel and isolated ground and neutral at the subpanel in the detached structure. In addition, they require ground stakes at the subpanel. NEC will (or did, I am not sure about the latest NEC rev) allow the ground wire to be smaller than the feeders. The goal here is to keep only one connection between GND and neutral at the main panel. The separate ground run back to the main panel is to cover situations where the neutral may become disconnected and prevent a return path through ground (real ground as in dirt).

So you really want 2-2-2-4 with red, black and white connected to 2 and green connected to 4.


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## Holbs (Nov 4, 2012)

I wired my attached 2 car garage… for it was simple. But a detached building? Yep, I would go licensed electrician for sure. The depth of the conduit, HOW it raises out of the ground, HOW it penetrates thru the wall, bleh bleh bleh. Also, if you get it inspected and call it a "subpanel", get ready for a scowl  I was told (by NV inspector) it's not a subpanel but… something else (forget). If I would of written "subpanel" on the initial plans for the permit, they would of said no to the whole thing.


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## Woodmaster1 (Apr 26, 2011)

I wired my detached garage for 200amps. I did the run myself because it was 3' from the pole. It had to be inspected before the city would hook it up.


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## REO (Sep 20, 2012)

Just because it works doesn't make it right. I have heard that placing a separate ground rod at the sub panel is being accepted I don't know from my own experience though. I do know that they have gotten very stringent on how the ground is installed though and in some cases it is required to be set in the foundation of the building. dryers and stoves now are required to be wired with four leads regardless if the appliance splits the 220 internally for 110. A ground is required to be a separate conductor until joined in the main panel. The ground cannot be used as a current carrying conductor and is meant for safety only. Of course it will work that way, but the safety of the system is reduced. If the neutral for some reason is interrupted, bad connection causing high resistance for instance, someone touching the equipment can become the path of least resistance. Of course this could happen in turn with the ground as well but you have more than doubly reduced the possibility. I have seen the way some people stuff the wires into the wire nuts using a yellow instead of a red because it is in their hand. long and short the extra wire is not that much additional expense for the additional safety.


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## Tennessee (Jul 8, 2011)

No to aluminum.
Yes to 2-2-4.
Also pay attention to the Christmas tree rule - in other words, the top of the tree is the smallest and final breaker. So you put a 100 amp breaker in the main box coming into your sub-panel, and run maybe an 80 amp breaker in your sub panel as a main.
That way, you blow the sub before you overload the main panel back at the house. Always done it this way in four of five shops I've owned as I moved around - always kept me safe. Also, run some extra ground bars into the ground with the sub - usually two at least eight feet apart outside. Use both a neutral bar AND a ground bar in your sub. Be safe not sorry.


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## mcg1990 (Nov 11, 2014)

Thanks everyone.

I'm going with an electrician (a different one than who insisted on 2-2-4).

This electrician is well known and trusted in the area and uses 2-2-2-4, but the only thing throwing me off is the whole issue of floating the ground and running it back to the main panel. This is instead of grounding at the subpanel, and is done to avoid feedback and all that stuff.

It makes sense to me, but my reading has led me to believe that code requires grounding rods.. Now, I'm not doing it strict to code, but I still want it safe. Can anyone explain to me floating vs grounding rods?


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## TopamaxSurvivor (May 2, 2008)

> Now, I m not doing it strict to code, but I still want it safe.


That is an interesting contradiction. You only get one of those two options; by code and safe or scabbed in any old way that feels good at the time (I guess).

The National Electric Code requires 4 conductors for 120/240 single phase: 2 hot, 1 neutral (current carrying grounded conductor) and the equipment ground. You also need ground rods at the subpanel that connect to the equipment ground. The equipment ground and the neutral are separate once they leave the main service where they are bonded together. I asume that is what you mean by "floating ground". You also need a main disconnect in the detached building that kills everything with a single switch. It will probably be in the subpanel.

There has been a lot of work done testing grounding systems in the last few decades. The "book" on grounding has literally been written. There were many eye opening discoveries that no one had ever dreamed of. It was optional to drive ground rods or run a equipment ground conductor to a detached subpanel 30 years ago. It would have been legal to use the 3 wire option in those days, but not anymore. The current code requires both the equipment grounding conductor and driven rods at the detached location. The code is constantly changing. There have been lots of major changes in the last few updates, every three years, including a total revision. There are lots more coming with the 2014 edition probably adopted about July 1 of this year in most locations. I'm glad I retired before I had to worry about this new code ;-)

I really feel sorry for the public trying to get the truth about electrical work. Here in WA, there is a strict licensing law and enforcement. Yet, there are still handymen and illegal contractors doing dangerous things that border on arson.

BTW, welcome to LJ!


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## EEngineer (Jul 4, 2008)

Can anyone explain to me floating vs grounding rods?

Nope! Let's get this part straight at least - there are no floating grounds! That is dangerous for a number of reasons.

In a three wire feed to a detached building, you run two hots and neutral out to a subpanel. The subpanel then *requires* a ground stake connected to equipment ground and *neutral is bonded to that ground* at the subpanel. Be aware that this no longer allowed by the NEC.

In a four wire feed to a detached building, two hots, a neutral and a ground are all run to the detached building. In this case, *neutral is not bonded to ground* at the subpanel. Ground stakes used to be optional in this situation, now they are required by NEC. I assume this is what you mean by "floating ground". But it is still connected to a good solid earth ground back at the main panel.

Now, how do I know this? I recently rewired my detached garage and installed a subpanel. I ran a three wire feed initially but wondered why there were two separate bonding connections in the subpanel I bought. After researching the NEC, I had to pull the fourth wire (ground) and make sure that neutral and ground were separated at the subpanel. When I had it inspected, the inspector looked specifically for this and told me it would not have passed without 4-wire feed.

Google it! I did. You'll find enough horror stories to convince that this is the right way to wire things. Problems come up when any one of the feed wires might open. In the case of three wire feed if the neutral opens, fault current might return through real ground (dirt!), In this case there might be enough limit to current that main breakers would never trip under faults. In the case of four-wire feed, the ground connection back to main panel might open leaving the grounds at the subpanel truly floating and this is dangerous. Thus the newer requirements for ground stakes at the subpanel with four-wire feed.


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## mcg1990 (Nov 11, 2014)

I'm definitely now using 4 wire (2-2-2-4) and will have a licensed electrician make the connections.

I think my incorrect use of contractor spiel has led to some confusion. I apologize, as you've all put a lot of much appreciated effort into your responses.

I'm running 4 wires to this subpanel, and now need to know how to ground it. Do I:
1) Bond neutral and ground together on the same grounding bar in the subpanel. If so, where does it go from there? This doesn't seem correct to me as I'm running 4 wires but this would only give me 3 connections.. 2 hots are sorted, but then I've got a neutral and a ground going to the same grounding bar, in that case I may as well use 3 wire feeder, but that's not correct so…
2) Keep neutral and ground on separate bars. The ground hooks up to the ground on my 4 wire feeder, and is run *solely *back to the main panel to be grounded.
3) Keep neutral and ground on separate bars. The ground runs to grounding rod(s) located at the subpanel. In this scenario are they also grounded at the main panel, or is the subpanel ground kept separate from main panel ground?


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## TopamaxSurvivor (May 2, 2008)

Good thing you are having a licensed electrician. He should know know do do this properly.

4 wires are required. The neutral and equipment ground are separate after they leave the main panel.

The sub panel grounding bar and neutral bar will be separate in the sub. The panel will come with a "bonding screw" to bond the neutral to the panel enclosure. Do not install it. There are brands of panels that will have the bonding in place from the factory. If yours does, remove it. It should be identified with a green marking screw.

The new ground rods connect to the grounding bar, not the neutral. They are totally separated. At the main panel, the grounds and neutral all go to the same bar and have a bonding to the panel enclosure. This is at the main panel only. If you have 5 sub panels in detached structures, the ground will be separate in each and they all require the additional ground rods.

*The ground runs to grounding rod(s) located at the subpanel. In this scenario are they also grounded at the main panel, or is the subpanel ground kept separate from main panel ground?* The 4th wire you pull from the main to the sub is the ground conductor. It connects the main panel neutral and to the sub panel ground bar. The ground rods also run to the sub panel ground bar. There should be existing ground rod or rods (depending on the age of the installation) at the main panel.

All your branch circuit grounds go to the grounding bar and all a the neutrals go to the neutral bar. I have seen the branch circuit grounds and neutrals intermingled in a properly installed sub panel.

Grounding is the most confusing issue in the code. The are more corrections written for it than any other article. In the last 45 years, I have had an occasional inspector write a correction for a properly grounded installation ;-)) I have had an electrical engineer specifying a total service rebuild rather than put in a small control transformer because he did not think the new transformer would work because of grounding issues. If he had been correct, the entire power gird and distribution system in this country would not function! Do not feel bad about the confusion. Even inspectors do not agree on the proper grounding for some installations. On one job, the power company and state inspector could not agree on the proper installation! I only relate this to point out how confusing the issue can be for professional, let alone the layman.

The latest requirement for grounding is to use a ufer ground instead of ground rods for new structures. That is connecting to the rebar in the footing instead of using ground rods. Here is WA, if you do not get this done and inspected at the time of the footing pour, you have to wrap the building with a few laps of copper wire to satisfy the grounding requirements. Hopefully, ground rods will suffice for you.

I will make a comment on the brand of panel. Square D and Cutler Hammer are the only 2 brands I would install. If the customer wanted another brand, they needed to find another electrician. Most brands of 15 and 20 amp breakers will hold a dead short long enough to melt a wire the size of a paper clip. Square D and Cutler Hammer have both thermal and magnetic trip. They will save the paper clip. A dead short caught by them will usually not leave a burn mark in a metal enclosure. Most of the others will leave very noticeable burn marks with a little copper contamination to boot.


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## WhyMe (Feb 15, 2014)

As a sub feeder 2-2-2-4 Al is to be overcurrent protected to no more than 90 amps.


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## TopamaxSurvivor (May 2, 2008)

> As a sub feeder 2-2-2-4 Al is to be overcurrent protected to no more than 90 amps.


The code is too complex for a layman to simply look up an answer. 310.15 B 7 slows #2 Al for 100 amp feeder and service. Even us pros get it wrong most of the time ;-)


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## Dal300 (Aug 4, 2011)

To make this even more complicated, in your sub panel and main panel, you will have the ground attached to the same us as the neutral. 
The two legs of 110-125 volts are the only ones that are connected to the breakers.

'IF' you have something like an RV, you do NOT bond the ground to the neutral in the rv, it is ONLY bonded at the panel.
If it is bonded at the rv breaker panel, the body of the rv will become, 'LIVE'. This means that if you touch the metal parts of the rv and the earth, you will get zapped!

Treat this info the same as a metal tool like a table saw or lathe.

Good luck to you, I think you will need it.


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## todd1962 (Oct 23, 2013)

I wired my own shop, however I had it permitted and inspected! If you are not comfortable doing it then get an electrician…


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## WhyMe (Feb 15, 2014)

> As a sub feeder 2-2-2-4 Al is to be overcurrent protected to no more than 90 amps.
> 
> The code is too complex for a layman to simply look up an answer. 310.15 B 7 slows #2 Al for 100 amp feeder and service. Even us pros get it wrong most of the time ;-)
> 
> - TopamaxSurvivor


Sorry to say you got it wrong. 310.15(B)(7) is for when the feeder is the main service supplying the total supply to a dwelling. As a branch feeder from a main service panel to a sub-panel you have to use table 310.15 (B)(16). You can use 75 deg. C which is 90A for #2 Al. I'm not a layman.


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## TopamaxSurvivor (May 2, 2008)

I'm sure glad I put the disclaimer about "even us pros get it wrong most of the time ;-)" I'm not sure if that is a local interpretation in your part of the country, but it clearly states, "........service-entrance conductors, service lateral conductors, and feeder conductors that serve as the main power feed to each dwelling unit and are installed in raceway or cable with or without equipment grounding conductor."

In my experience, our inspectors accept work consistent with residential occupancy requirements to be applicable to the entire site. Now, for the disclaimers ;-)) I am a commercial and industrial motors and controls guy but have done residential work. Applications of code vary between various jurisdictions including the state and cities of this metropolitan area. Travelers coming into this area have commented many times how different the requirements are here. All my experience had been in WA and a little in Alaska.

As always, your mileage may vary. Get a licensed contractor to preform the work with permits and inspection. I'll even throw in the one the authorities having jurisdiction use: Just because the work has been inspected and signed off does not relieve the owner or contractor's responsibility for any code violations. ;-)


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## TopamaxSurvivor (May 2, 2008)

WhyMe, What edition of the code are you using. I'm looking at 2011 and do not intend to spend $75 on a new one. It will not apply to retirement ;-))


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## WhyMe (Feb 15, 2014)

Currently 2011. The 2014 310.15(7) has been changed/clarified.

Watch this video starting at 34:35.





Also if you look for other building/structures supplied from a feeder or branch circuit it's covered in section 225 II which is about outside feeders and branch circuits.


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## muleskinner (Sep 24, 2011)

Topa - besides the NEC, don't forget those WACs and RCWs. I sure as hell don't miss those code update classes.


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## TopamaxSurvivor (May 2, 2008)

WhyMe, I only watched that once. I guess I stand corrected. It isn't the first time ;-) Nobody gets through this trade without corrections. I have gone a year a few times without one. One year, my first was in December ;-( I hate it when that happens.

There used to be a clause that said unnecessarily complicated wiring is illegal. I think it went away about the same time as requiring everything in a "workman like manner"; too vague for enforcement. About 15 years ago when they put in different wire fill for each type of raceway instead of all ½" raceways being the same, I knew we were in big trouble. I thought that the code was in violation of itself for becoming unnecessarily complicated, but the unnecessarily complicated clause was gone! It is getting worse. I'll be like a 3 phase delta 120/240 service in a couple more code changes, totally obsolete ;-)


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## TopamaxSurvivor (May 2, 2008)

> Topa - besides the NEC, don t forget those WACs and RCWs. I sure as hell don t miss those code update classes.
> 
> - muleskinner


I may go for curiosity. I'll always pay my Master License fee as long as I can walk. You just never know what the future holds. One can always catch up on the CEUs. That license has a extra special meaning. I got it in 1985 when less than 2% of the guys taking the test passed. There was an article in the Seattle Times that spring about the lawyers whining about the bar exam being too hard as only about 50% passed. The Times pointed out less than 2% were passing the electrical administrator exam so the attorneys had it pretty good ;-)


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## mcg1990 (Nov 11, 2014)

I hope I'm not responsible for ending any friendships by bringing up this topic.. looks like it's caused quite the debate.

I appreciate all of the replies, but I'm even more overwhelmed than before! To quote The Office, "Can you please explain this like you would to an 8 year old… ok, hmm, yes, I see. Can you please explain this, again, like you would to… a 5 year old?" I'm that 5 year old.

So, going back to the details: 2-2-2-4 Aluminum running from 90A breaker in my 200A main panel, going to my 100A subpanel in detached building. 2 hot wires hook up easy enough. I'm left with neutral and ground from my 4 wire feeder, and in my panel I have neutral and ground to sort out also.

My branch circuit neutrals go to a neutral bar, and my circuit grounds go to a ground bar.

My neutral bar connects directly to the neutral on my 4 wire feeder, leaving me only with the grounding dilemma.

This is where my electrician is suggesting something contrary to the advice I see here. He's telling me not to ground at the subpanel, but rather connect the ground wire on my feeder to the grounding bar in the subpanel, and let my main panel do the work in terms of grounding.

Advice here is telling me to ufer ground at the subpanel. Now, whether it's ufer grounding or grounding rods, what exactly do I do with my 4th grounding wire on my feeder? Does that connect to it also, so that both my feeder ground and my subpanel ground connect to the ufer/grounding rods?


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## TheFridge (May 1, 2014)

90 not 100.

Grounds and neutrals seperated in sub panel.

Ground bus will mount directly to the panel can. The ground from your feeder goes straight to the ground bus. All your branch ckt grounds land there.

If the shop is an older shop it is most likely grandfathered in and not requiring an ufer ground. If it's and old stick framed shop, then I can't think of a good reason to have a ground rod or ufer ground.

Use direct burial wire or in PVC.

In PVC, 18" to top of pipe in areas not subject to to vehicle traffic. 24" if it is. Schedule 40 PVC is plenty unless it's in an area subject to damage.

Edit: if you need a ground rod or ufer ground it will land on the ground bus.

And I wouldn't say not doing some things to code is dangerous. It depends. But it's always a liability to do it for a living and not do it properly.

Not to mention grounding/ bonding is a major issue home inspectors look at when buying/selling a house. So you'd have to fix it if you ever wanted to sell and you did it wrong.


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## WhyMe (Feb 15, 2014)

As said neutral is isolated from the ground at the sub-panel. 2 ground rods should be driven at least 6ft apart at the detached building connected together by one continuous #6 copper wire connected to the sub-panel ground bar.


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## TopamaxSurvivor (May 2, 2008)

> This is where my electrician is suggesting something contrary to the advice I see here. He s telling me not to ground at the subpanel, but rather connect the ground wire on my feeder to the grounding bar in the subpanel, and let my main panel do the work in terms of grounding.
> - mcg1990


I'd find it hard to believe the National Electric Code doesn't apply in your area. What part of the country are located?


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## wapakfred (Jul 29, 2011)

Topamax, the code may apply to my part of the world, but it isn't enforced…much the same as if it didn't exist. As I understand it (maybe incorrectly) the NEC is much like the UCC; available, but each jurisdiction has to adopt it. Do I misunderstand that?


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## mcg1990 (Nov 11, 2014)

The county website states that it enforces the 2008 NEC book :/


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## rantingrich (Sep 19, 2014)

AS far a GROUNDIng I have heard and followed that if the Structure is NOT attached to the main building one should GROUND at the structure near the new panel. In my case that would be two 8 foot long grounding rods 6 feet apart


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## TheFridge (May 1, 2014)

Yep. I was way wrong.


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## WhyMe (Feb 15, 2014)

> AS far a GROUNDIng I have heard and followed that if the Structure is NOT attached to the main building one should GROUND at the structure near the new panel. In my case that would be two 8 foot long grounding rods 6 feet apart
> 
> - rantingrich


This is true that an outbuilding supplied with power from another building needs to have its own earth ground electrode system. But the earth grounding system at the outbuilding is not the same as the equipment ground conductor that must run back to the main service panel at the source building. You need both.


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## oldnovice (Mar 7, 2009)

*No to aluminum, yes to an electrician!*


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## TopamaxSurvivor (May 2, 2008)

> Topamax, the code may apply to my part of the world, but it isn t enforced…much the same as if it didn t exist. As I understand it (maybe incorrectly) the NEC is much like the UCC; available, but each jurisdiction has to adopt it. Do I misunderstand that?
> 
> - Fred Hargis


Yes, I believe that to be correct. The state of WA did not adopt the 2008 code when the economy crashed. They said they didn't have the money to train inspectors. With the 2011 adoption, we got a double dose! ;-(



> This is true that an outbuilding supplied with power from another building needs to have its own earth ground electrode system. But the earth grounding system at the outbuilding is not the same as the equipment ground conductor that must run back to the main service panel at the source building. You need both.


I think this is where a lot of the confusion begins; they are different items, yet they are connected together in the subpanel.

*mcg1990,* Not to add to the confusion, but depending on the maximum load and distance to your shop, anything over 100-150 feet, you may want to look at the voltage drop.


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## TheFridge (May 1, 2014)

Aluminum a fine for feeders if you choose.

Noalox is a must though.


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## Dal300 (Aug 4, 2011)

This makes my little maintenance guy noggin hurt.

In our little piece of heaven, I don't have to follow current NEC code. Only what was current at the time the rules were incorporated into the inspection statutes.

Having said that, I have the 2004 book, and I follow it the best way I can, but I am not required to have an inspection by the county, (we are outside the city limits plus our park is grandfathered to early 1960's regulations for some strange reason). I haven't figured out why, so I just try to update everything I do to the regulations the county requires.

I was never an electrician. I've done "Harry Homeowner" type stuff and was so embarrassed that I redid it to code, (Before the internet).
I have worked for an electric utility as an IT guy, plus I had to run parts and pieces at times. 
Our engineers and master electricians taught me so much that doing things halfast is no longer an option. I am compelled to do it right.


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## TheFridge (May 1, 2014)

On #2 alum @ 150' with a 40A load it's a 1.6% drop. Should be fine.


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## Wiltjason (Jan 10, 2013)

Hi. I'll throw my 2 cents in on this. Im and a journeyman electrician and have 20+ years experience. The NEC says says that the ground and neutral be bonded at the first means of disconnect and then must be seperate from there on. This means that the power company can run triplex or 2-2-4 aluminium from the transformer to your panel, then at your panel in your house and there the grounds and neutrals are to be bonded together ( alittle green screw from the neutral bar to the panel cabnet) then from there you need to run a 4 wire 2-2-2-4 either direct bury or threw conduit ( make sure you have the proper cable for which ever you do) to your 100 amp subpanel in your shop. At the house you will want to put a 100 amp breaker . And at your subpanel you need to seperate your grounds and neutrals


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## TopamaxSurvivor (May 2, 2008)

> On #2 alum @ 150 with a 40A load it s a 1.6% drop. Should be fine.
> 
> - TheFridge


Yes, it should be. That is the point where I like to start taking voltage drop into consideration; well before I get caught with my "pants down" ;-) Especially when there are motor starting loads at the end of the line. I know the code doesn't mention it, but I normally start my considerations at the point of origin of the service. A long lateral to the main can have significant loss on small conductors feeding a 200 amp service. Our power company here only uses about a #1 or #2 in many cases. I called them just before I retired inquiring about an underground service change to 200 amp. The original installation included a 200 amp meter base, but the service lateral was #1 or 1/0. They said all of our laterals are rated for 200 amp minimum. They operate under a different set of standards, but that could significantly affect starting larger motors.


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## WhyMe (Feb 15, 2014)

> Hi. I ll throw my 2 cents in on this. Im and a journeyman electrician and have 20+ years experience. The NEC says says that the ground and neutral be bonded at the first means of disconnect and then must be seperate from there on. This means that the power company can run triplex or 2-2-4 aluminium from the transformer to your panel, then at your panel in your house and there the grounds and neutrals are to be bonded together ( alittle green screw from the neutral bar to the panel cabnet) then from there you need to run a 4 wire *2-2-2-4 *either direct bury or threw conduit ( make sure you have the proper cable for which ever you do) to your 100 amp subpanel in your shop. *At the house you will want to put a 100 amp breaker* . And at your subpanel you need to seperate your grounds and neutrals
> 
> - Wiltjason


This info is not correct. See my post #20. #2 Al can be overcurrent protected to no more than 90A as a branch feeder. You are confusing allowable amps on main service feeders vs. branch circuit/feeders.


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## mcg1990 (Nov 11, 2014)

My electrician just quoted me $1400. He's out, and it's back to me doing the work. I'm comfortable doing it, I just need to know what to do. 
If I'm correct it's this:

2-2-2-4 Al going from a 90A breaker in my main panel using Noox.
Conduit run from mainpanel all the way til the cable is at it's bend ~24" underground, same at the other end.
Neutrals and grounds on separate bars in my subpanel. 
2 8ft ground rods 6ft apart down at the subpanel, connected with #6cu.

Here's where I'm confused: What happens to my ground? Specifically - I have my grounding bar in my subpanel and grounding bar at my panel. It would be easy if I simply connected those 2 together, but how do I hook up my 6ft ground rods?

Do I run my ground back to the main panel at all? Or just connect my branch grounds directly to the bar, directly to my ground rods outside. If I do have to do something with the 4th wire in my feeder, where does that go? And if I don't have to, can't I just use 3 wire feeder and keep my ground entirely separate from my main panel?

*Edit
Is *THIS* pretty much what I'm doing?


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## TheFridge (May 1, 2014)

1400$ doesn't sound like a bad price. Ground and neutral lands in the same place at the main panel.

Your 4th wire of your feeder (#4) lands on the ground bus in the sub panel with all circuit grounds, and the wire to the ground rod. Must be continuous from panel to both ground rods I believe.

Your neutral and ground land together in your main panel because it's where your ground and reference to ground are derived. So after that point, it shouldn't be reconnected in any way to the neutral so it only carries fault current and none of the load.

Power companies do not run a 4th wire (ground) to your service. The ground is derived at your first disconnection means.


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## TheFridge (May 1, 2014)

Yep


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## mcg1990 (Nov 11, 2014)

Will I have issues when connecting up my grounds to the ground bus seeing as my feeder is aluminum and the wire to my rods is copper?


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## Dal300 (Aug 4, 2011)

I hesitate to mention it, but you are gonna use the 'goo' for that Aluminum wire, aren't you?
If you don't the aluminum will corrode and eventually cause heating of the wire which will lead to hardening, which will lead to brittleness, which, when the ground moves or the shop gets cold can cause breakage of the wire.

I have stayed away from Aluminum wire since the 1980's, but many people still use it. The stuff can be a nightmare, especially underground.

No matter what the cost, #2 copper will make you a lot happier in the long run, and could actually be a plus if you ever decide to sell the old homestead.

Good Luck.


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## TheFridge (May 1, 2014)

Use ideal noalox for any aluminum wiring terminations.

Aluminum lugs are dual rated, typically, for copper and aluminum wiring while copper lugs are strictly copper (pretty sure).

Aluminum wiring is perfectly fine. Above or underground makes no difference.


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## WhyMe (Feb 15, 2014)

Today's aluminum wire is not the same from years ago. Using it for services and branch feeders is fine.


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## exelectrician (Oct 3, 2011)

Aluminium is a resistor compared to copper, why waste energy heating up the ground? Aluminium wire is a BIG NO from me.


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## TheFridge (May 1, 2014)

Ampacity is ampacity. That's why its sized up from copper.

Making the resistance equal.


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## WhyMe (Feb 15, 2014)

> Aluminium is a resistor compared to copper, why waste energy heating up the ground? Aluminium wire is a BIG NO from me.
> 
> - exelectrician


With that understanding of using aluminum wire vs. copper wire no wonder you're an "*ex*electrician".


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