200 Amp Underground Service 330 Feet

[ptonsparky]

Table C10. RHH, RHW, 350 kcmil, 3" Sch40 PVC, 3 conductors.

Thank you.

Now, how do I know if it has *outer coverings or not.

I know...measure it.

Table 5. .7870 vs .5958. Area.

 

[electrofelon]

Table C10. RHH, RHW, 350 kcmil, 3" Sch40 PVC, 3 conductors.

Prob want C10 (a) , compact conductors.

 

[infinity]

Prob want C10 (a) , compact conductors.

That would work.

 

[Greg1707]

Chapter 3 Wiring methods

Chapter 3 Wiring methods

Hello,

I am writing an estimate up for a residential underground service. It is a bit longer than ones that I have done in the past and I want to double check my design. The meter pedestal is going near the utility pole that is on the edge of the property. I will have a disconnect at the meter socket. I am running the underground service complete from the pole to the house.

I am thinking that I will use 3 inch conduit and 350 aluminum URD. It will be a 4 wire from the pedestal to the house because of the disconnect. Does anyone see an issue with this? I think that 4/0 is too small for the voltage drop on the run. I appreciate the insight.

Is URD allowed? I did not think it was listed in Chapter 3?

 

[winnie]

On the voltage drop question...

On the voltage drop question...

As others have mentioned, the actual load on these conductors is likely to be quite a bit less than 200A, even though this is a 200A service.

The other side of the coin is that any large loads (HVAC motor loads, well pump, etc.) might produce transient high currents which would cause lights to flicker.

So do keep in mind both steady state and transient voltage drop, although it may make more sense to change the loads than to increase to size of the service conductors. For example perhaps some sort of electronically controlled well pump rather than something that starts across the line.

-Jon

 

[ptonsparky]

Is URD allowed? I did not think it was listed in Chapter 3?

Depending on your AHJ, many of us can use it. Depends on the other ratings it may have or perhaps a certain distance into the building.

 

[Tony S]

Sure. Let's line up a dump truck, a skidsteer, some guys with shovels and put a bunch of sand in the bottom of the ditch, send them home while I lay my wire in, then call them back to put some sand on top, then backfill the rest of the ditch with dirt.

Or, dig a ditch, I throw my conduit in and the backhoe can throw dirt on top as soon as I'm out of the way.

Even better than that... We have a locator and a fault finder in our shop. I go out every year and dig up a burnt up direct bury wire and patch it and charge a lot of money. Never done that on wire run in conduit.

Last year I designed a job and had to include 90 tons of quarry sand in the price. That was using the minimum of bedding and cover. I left it to the ground workers. So much easier when I worked in quarrying.

 

[Cow]

Usually I just give the grounds site crew foreman a case of beer and he takes care of it. No need to do things the hard way.

I have to chuckle at this.

I'm sorry, but all the diggers I know aren't going to bring sand on site, bed the bottom of the ditch for us to lay our wire in and then bed the top with sand before using the native soil to backfill with, just for a case of beer.

To think every electrician in America should be able to talk their diggers into doing this extra work for a case of beer is just being naive. Our diggers over here work for money. Just like we do.

PVC is cheap. We use PVC. Done.

And no extra trips to the store for beer required.

 

[electrofelon]

And no extra trips to the store for beer required.

So just one trip, for you and your guys

 

[kwired]

I understand the conduit; just not using URD and conduit.

You people are obsessed with rocks, I get it; but you know you could backfill with sand like I do when necessary..

Is that less cost than using conduit?

Sure. Let's line up a dump truck, a skidsteer, some guys with shovels and put a bunch of sand in the bottom of the ditch, send them home while I lay my wire in, then call them back to put some sand on top, then backfill the rest of the ditch with dirt.

Or, dig a ditch, I throw my conduit in and the backhoe can throw dirt on top as soon as I'm out of the way.

Even better than that... We have a locator and a fault finder in our shop. I go out every year and dig up a burnt up direct bury wire and patch it and charge a lot of money. Never done that on wire run in conduit.

I have, but is pretty rare.

Is URD allowed? I did not think it was listed in Chapter 3?

Plain URD is composed of USE rated conductors - those are chapter 3 conductors but are not rated to enter a building.

There are assemblies that have individual conductors marked with multiple ratings - typically USE, RHW, RHW-2 - those can enter a building.

 

[jumper]

I have to chuckle at this.

I'm sorry, but all the diggers I know aren't going to bring sand on site, bed the bottom of the ditch for us to lay our wire in and then bed the top with sand before using the native soil to backfill with, just for a case of beer.

To think every electrician in America should be able to talk their diggers into doing this extra work for a case of beer is just being naive. Our diggers over here work for money. Just like we do.

PVC is cheap. We use PVC. Done.

And no extra trips to the store for beer required.

I did not say that, I use PVC sometimes and sometimes URD, I was mostly questioning why the use of both.

Putting a direct burial cable assembly in conduit seems strange to me. Like piping UF cable...why?

 

[kwired]

As others have mentioned, the actual load on these conductors is likely to be quite a bit less than 200A, even though this is a 200A service.

The other side of the coin is that any large loads (HVAC motor loads, well pump, etc.) might produce transient high currents which would cause lights to flicker.

So do keep in mind both steady state and transient voltage drop, although it may make more sense to change the loads than to increase to size of the service conductors. For example perhaps some sort of electronically controlled well pump rather than something that starts across the line.

-Jon

+1.

Might even cost less or about same to parallel 4/0 instead of running 350, but gives you more overall CSA and less voltage drop.

 

[Little Bill]

I did not say that, I use PVC sometimes and sometimes URD, I was mostly questioning why the use of both.

Putting a direct burial cable assembly in conduit seems strange to me. Like piping UF cable...why?

See post #15

 

[jumper]

See post #15

Which explains the advantages at times of using conduit over direct burial.

Totally understand.

Each method has its good and bad. No problem.

I simply asked why shove URD into PVC?

URD was made to be buried, so I bury it.

If you are getting it at a better price than regular conductors or if it is just more readily available , that I would understand.

 

[kwired]

Which explains the advantages at times of using conduit over direct burial.

Totally understand.

Each method has its good and bad. No problem.

I simply asked why shove URD into PVC?

URD was made to be buried, so I bury it.

If you are getting it at a better price than regular conductors or if it is just more readily available , that I would understand.

Around here is usually is better price than running single conductors or nearly same but already in one assembly and ready to pull without having to measure off or set up multiple reels.

 

[Little Bill]

Around here is usually is better price than running single conductors or nearly same but already in one assembly and ready to pull without having to measure off or set up multiple reels.

2-2-4-6 is about $1 a foot here. Haven't bought any 4/0 lately but it is way cheaper than single conductors as well.

 

[packersparky]

Which explains the advantages at times of using conduit over direct burial.

Totally understand.

Each method has its good and bad. No problem.

I simply asked why shove URD into PVC?

URD was made to be buried, so I bury it.

If you are getting it at a better price than regular conductors or if it is just more readily available , that I would understand.

It was mentioned in post #12 that URD is cheaper that individual conductors.

 

[jumper]

It was mentioned in post #12 that URD is cheaper that individual conductors.

You do not think that I actually pay attention?

Cheaper, I understand.

 

[Frontman4u]

Where are you finding your ampacity for URD as it is a utility cable and the NEC doesn't recognize it?

Also, read 2017 NEC Art 338.12(B)(1-3) and make sure that you're not creating a hazard. USE contains a moisture-resistant covering, but not required to have a flame-retardant covering.

 

[kwired]

Where are you finding your ampacity for URD as it is a utility cable and the NEC doesn't recognize it?

Also, read 2017 NEC Art 338.12(B)(1-3) and make sure that you're not creating a hazard. USE contains a moisture-resistant covering, but not required to have a flame-retardant covering.

At one time URD was only a utility cable. Now some are and some aren't.

Pretty common around here to see multiplex assemblies that have multiple ratings on individual conductors, USE, USE-2, RHW, RHH, RHW-2