What size underground grey PVC tube is required for this applicatoin? Total underground run will be ~150', max circuit load will be 60amps / 220 volts. Wire will be 3 strands of #2 and 1 stand of #6.

Personally, I'd do 2", but 1.5" should do it. You didn't say how many bends either. Why the jump from #2 to #6 for ground or neutral?

Sounds like you have nearly 1.25" of cable to pull through a conduit.

1.5" conduit will barely do the job, 2" minimum.

BUT

you're burying conduit - a lot of it - what if you one day want to run 125A service out there, maybe for an air compressor and plasma cutter. Where 60A may be borderline.

If I were in your shoes I would probably run 4-5" to cover any possibility. Overkill for sure, but to me it would be worth it.

I would run 3" minimum out of preference only.I don't have Ugly's book handy right now. Why grey? CPVC is UV protected. You shouldn't need the UV protection 2' - 3' under dirt.

Sounds like you have nearly 1.25" of cable to pull through a conduit.

1.5" conduit will barely do the job, 2" minimum.

BUT

you're burying conduit - a lot of it - what if you one day want to run 125A service out there, maybe for an air compressor and plasma cutter. Where 60A may be borderline.

If I were in your shoes I would probably run 4-5" to cover any possibility. Overkill for sure, but to me it would be worth it.


Seeing as how #2 copper with 90 degree C insulation is going to be good for 125Amps and still meet the 3% rule with a 150' run what are you going on about?

2" conduit should be good for 9-#2 conductors (depending on insulation type and thickness) so anyone who recommends 4"+ conduit should put down the crack pipe.

Just checking, but is the #6 for a ground? As far as I know, if you are going to another building and have a subpanel in it, the building will have to have it's own ground and you cannot have any ground wire in between the two buildings. You also don't bond the neutral+ground busses in the subpanel. Just mentioning it, since that's what the inspectors required for my detached shop...

If you don't have a seperate subpanel, or it's not a detached building then I have no idea.

Seeing as how #2 copper with 90 degree C insulation is going to be good for 125Amps and still meet the 3% rule with a 150' run what are you going on about?

2" conduit should be good for 9-#2 conductors (depending on insulation type and thickness) so anyone who recommends 4"+ conduit should put down the crack pipe.

#2 copper is going to lead to a 7 volt drop, or 3% @125A. Sure, he met the 3% rule, but barely.

EVERY person I know that has run power or conduit over a long distance underground has regretted not running large enough cable for unkown future needs or large enough conduit to handle any possibility that could show up. In my opinion there is more work in burying it than the materials cost. (well, that was before copper went through the roof)

The poster also didn't state if it was a straight pull or one with 3 bends (all that is allowed per code without a J-Box). the more bends, the harder the pull, the more a larger conduit size will help.

I stated 4" was going to be overkill, but I don't know if I'de go with just 2".

#2 copper is going to lead to a 7 volt drop, or 3% @125A. Sure, he met the 3% rule, but barely.

EVERY person I know that has run power or conduit over a long distance underground has regretted not running large enough cable for unkown future needs or large enough conduit to handle any possibility that could show up. In my opinion there is more work in burying it than the materials cost. (well, that was before copper went through the roof)

The poster also didn't state if it was a straight pull or one with 3 bends (all that is allowed per code without a J-Box). the more bends, the harder the pull, the more a larger conduit size will help.

I stated 4" was going to be overkill, but I don't know if I'de go with just 2".




The initial post was 60A, 2 gauge and 150' and by chance or planning he has sized the conductors such as they will still be code compliant for a 125A load if he uses copper conductors with a high enough temperature rating. For his intended usage 2" conduit more than exceeds code requirements and with LR ell's it is not a hard pull.

So going to 0 gauge copper for a 2% drop is what you would do for the sake of 2.5V in an application that may or may not come about? It is pretty easy to spend someone else's money over the internet.


Personally I would just go with Teck cable and direct bury it but not everyone has access to Teck cable at prices that make this an attractive option.

So going to 0 gauge copper for a 2% drop is what you would do for the sake of 2.5V in an application that may or may not come about? It is pretty easy to spend someone else's money over the internet.


No, I would oversize the conduit to support larger wire and still be pullable. That way, if a larger app came about, all I have to do is pull new larger wire.

While he is digging a trench, I would also run a second conduit of say an 1" or so for future data lines.

This is what "I" would do in his shoes.

What size underground grey PVC tube is required for this applicatoin? Total underground run will be ~150', max circuit load will be 60amps / 220 volts. Wire will be 3 strands of #2 and 1 stand of #6.

I would think this would be sufficient. #3 wire (THWN/THNN buried conduit) is rated for 100 amps and you're wanting to run #2. I'd use a 2" pvc... YOu want to use grey color because that is the color for electrical.

2 wires for 110v legs
1 wire for neutral
1 #6 wire for ground.

Just checking, but is the #6 for a ground? As far as I know, if you are going to another building and have a subpanel in it, the building will have to have it's own ground and you cannot have any ground wire in between the two buildings. You also don't bond the neutral+ground busses in the subpanel. Just mentioning it, since that's what the inspectors required for my detached shop...

If you don't have a seperate subpanel, or it's not a detached building then I have no idea.


Inspectors vary from state to state and even within different areas. When I did mine here a year and a half ago, I could have ran the ground from the house to the subpanel, or pound in the ground rod for the shop. I ended up doing both since the bare copper came with the cable that I ran. The inspector saw it and signed off on it. I don't remember for sure but why wouldn't it be o.k. to bond teh nuetral+ground busses in the subpanel?

The point is though, always stay within the code, but also be aware of the local requirements and nuances of the inspectors.

I don't remember for sure but why wouldn't it be o.k. to bond teh nuetral+ground busses in the subpanel?

The point is though, always stay within the code, but also be aware of the local requirements and nuances of the inspectors.

http://members.tripod.com/~masterslic/FAQ-2/18.html

Why isolate the neutral in a sub panel?...
The neutral is only bonded to ground at your service panel. At all other points throughout your house, there is no connection between the bare (or green) grounding conductor and the white neutral conductor. Under normal conditions, the grounding conductor carries no current. No current means there is no voltage drop along it, therefore anything "grounded" to this conductor is at the same potential (voltage) as ground. If you bond the neutral and ground at the sub panel, than stray currents from the neutral return could go thru the equipment ground on the electrical devices fed from this sub panel. If you isolate the neutral and ground at the sub panel, than any currents would go back to the main panel, and go to the service ground. The main panel is where the neutral and equipment ground should be bonded.
If you install a sub panel outside the building from the main panel, than you will need to drive a ground rod at this panel. A single branch circuit run to another building is not considered a sub panel.

http://members.tripod.com/~masterslic/FAQ-2/18.html

Why isolate the neutral in a sub panel?...
The neutral is only bonded to ground at your service panel. At all other points throughout your house, there is no connection between the bare (or green) grounding conductor and the white neutral conductor. Under normal conditions, the grounding conductor carries no current. No current means there is no voltage drop along it, therefore anything "grounded" to this conductor is at the same potential (voltage) as ground. If you bond the neutral and ground at the sub panel, than stray currents from the neutral return could go thru the equipment ground on the electrical devices fed from this sub panel. If you isolate the neutral and ground at the sub panel, than any currents would go back to the main panel, and go to the service ground. The main panel is where the neutral and equipment ground should be bonded.
If you install a sub panel outside the building from the main panel, than you will need to drive a ground rod at this panel. A single branch circuit run to another building is not considered a sub panel.

I understand that, but with a ground rod for the shop subpanel they are bonded at the subpanel.

I understand that, but with a ground rod for the shop subpanel they are bonded at the subpanel.

Nope.

Sub panel neutral and ground bars remain unbonded.

Nope.

Sub panel neutral and ground bars remain unbonded.


Why the rod then?

Why the rod then?

I think you want another ground for safety reasons... I would hate to lose the ground to the main panel and not have ground in the shop. I'm sure a licensed electrician can chime in here.

I had to have a separate ground rod (8') inserted into the ground and tied back to the subpanel, make sure the neutral and ground was NOT bonded when I installed my sub panel in my shop. My inspector even had me ground the I beams in my shop to the subpanel.... I guess you can never be too safe.


From this thread
http://boards.diynetwork.com/eve/forums/a/tpc/f/9221916776/m/7341096182

We get this.....

NEC 2002 250.32

Exception: A grounding electrode at separate buildings or structures shall not be required where only one branch circuit supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the conductive non–current-carrying parts of all equipment.
If a building is supplied by only one branch circuit with an equipment grounding conductor, there is no requirement to establish a grounding electrode system or connect to one if one exists.

If you feed a panel in the garage, you have a feeder, not a branch circuit and a grounding electrode system is required.

Most code "experts" say that if you use a multiwire branch circuit to feed more than one utilization equipment, you have multiple branch circuits, not a single branch circuit.

Understand the Definitions
To understand when the above locations require disconnecting means and ground rods, first the appropriate NEC definitions must be understood. For clarity, the following definitions are underlined in the article where used. Refer to the NEC for the full text of any code section cited here.

Branch Circuit. The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s).

Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.

Disconnecting Means. A device, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.

Feeder. All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.

Outlet. A point on the wiring system at which current is taken to supply utilization equipment.

Service Equipment. The necessary equipment, usually consisting of a circuit breaker(s) or switch(es) and fuse(s) and their accessories, connected to the load end of service conductors to a building or other structure, or an otherwise designated area, and intended to constitute the main control and cutoff of the supply.

Structure. That which is built or constructed.

The NEC requires a grounding electrode system for each building or structure [250.50], and for buildings or structures fed from one common service [240.32]. Ground rods are part of the grounding electrode system, and often are the only grounding system used for traffic signal and roadway lighting applications.

An exception to [250.32] does not require a grounding electrode (ground rod) if only one branch circuit feeds the building or structure, and the equipment grounding (green wire) conductor is run with the branch circuit. [225.30] states a multiwire branch circuit shall be considered a single branch circuit. For example, a “three wire” branch circuit (2 hots, neutral and equipment ground) could be run to a remote sign, and ground rods would not be required.

One Ground Rod or Two?
If the resistance of a single “rod, pipe or plate electrode” is not 25 ohms or less, then the single ground rod is augmented by an additional electrode, which is most often a second ground rod [250.66]. It is usually less expensive and easier to install a second ground rod then to test the ground resistance.

Purpose of Ground Rods
The purpose of the grounding electrode system is to stabilize the system voltage to ground and prevent over voltage from line surges or lighting [250.4(A)(1)]. Ground rods have no function in clearing a line to case faults.

Green Wire Required to Every Remote Building or Structure
An equipment grounding conductor (green wire) is required to be run to a remote building or structure, when fed by a single branch circuit or multiwire branch circuit, and is recommended for feeders. The equipment grounding conductor provides a low impedance path to the source for rapidly clearing line to case faults [250.90 and 250.96]. If an equipment grounding conductor is not run with a feeder, and there are no parallel paths, the grounded conductor (neutral) can be used for grounding and bonding of equipment [250.32(B)(2)].

Summary-Remote Building or Structure Ground Rods
Ground rods are not required by the NEC for a remote building or structure served by a single or multiwire branch circuit.

you only bond the nuetral at the main service. also terminals are only rated for 75*c so you size your wire by that not 90

Some more info. on installing a sub panel..

http://www.hammerzone.com/archives/elect/panel/sub_panel/01/new.htm

Use of ground rods

http://boards.diynetwork.com/eve/forums/a/tpc/f/9221916776/m/7341096182

Good explanation of why you don't want to bond ground and neutral on a subpanel.

http://www.ecmweb.com/mag/electric_grounding_vs_bonding_5/index.html

Man I love these threads! The original person ask a question and never seems to reply. Then we get to learn about who knows what and who doesn't. The best person for the job at hand and of course I get schooled.
Nice work and great info guys!:D

2" grey PVC conduit it will be - all straight runs. And yes, am gonna run a seperate 1" line as well.
The reason for #2 was this -> got a great deal on a few bundles of three #2's w/#6 ground. Per the specs #4 / #8 would do the job, but this deal came along so I went with it.

actually, 1 1/4" conduit is all you need. I'd step up to 1 1/2" though, just easier to find stuff for it (fittings and such)

I'd personally go with 2", up here we have pvc and DB2 lighter weight condiut that is cheaper for long runs. Normally only use the pvc to come out of the ground and exposed stuff.

In BC its against code to have more than one nuetral bond in a system regardless of it being in a different building. Nuetral is only bonded to ground in the service entrance switch or panel which is were your main ground cable going to your ground pad or rod is. The rest of the ground wires like the one in your piping would be just for bonding purposes.

Bigger size = more money. The code only requireds it to be 1 1/4" . My only reason to move up to 1 1/2", like i said, is most times it's easier to find LB's and other fittings (more common size nowadays) ... 2" or bigger is overkill, and money wasted. You have to think, on 3 or more conductors, you are only fillinf the conduit a maximum of 40% of its capacity. There is plenty of room to "make it easy" to pull.