1/2 or 3/4 burried conduit

[yeldogt]

running a conduit for a lamp post on the side of my house. Current way is a burried cable of unknown age (old). The new conduit will go into a new surface mounted box/ outlet on the wall of a new addition. how many wires can I have in a 1/2 ?

was thinking ideally 4 would be nice as it would allow an always hot for an outlet along with the switched lamp post -- my memory is a 20 amp circut. Will to be changing some of the grade with a lot of new top soil so I want to get this in prior as in some areas it's going to be 10" higher.

the 1/2 is easy to work with -- have a heat blanket . it needs to go out about 25' and make a 90 and go another 15' -- 90 up at each ends that will be made with the blanket

 

[imagineer]

Go with the larger conduit.

20 some odd years ago, when running new 100amp service to my pole barn, I was planning on larger conduit (1 1/2") for the power and smaller (1/2") for coax and Cat5. My electrician insisted on 3/4" for the non-power and it proved to be a wise decision. In the years since, I've had reason to pull other service through the 3/4" and had no problems.

 

[sparky 1971]

Use 3/4. 1/2 pvc is useless.

 

[pattenp]

The 1/2" is plenty for the circuit to the lamp post. It can handle up to 8 #12 thhn conductors.

 

[mike93lx]

Bigger is better, but 1/2 is plenty. That said, it's 4-5 sticks and you don't have to buy any fittings.

Doing your own bends will make for a smoother run, so that helps with using 1/2.

Either way will work fine and past the initial pull, you likely will never touch it again.

I'd do 1/2

 

[Shiftless]

With 4 number 12s I would go with 3/4 Instead of half. The difference in cost of 4 sticks of conduit is only what, maybe ten bucks? It will be less struggle pulling the wires. Isn’t that worth the small extra cost to you?

 

[sparky 1971]

There are a lot of people on here suggesting 1/2". There's no way in hell I will ever use 1/2" PVC for anything beyond using it as a sleeve for a piece of UF. 1/2" factory 90's are a ***** just to get a fish tape through, and it's not worth the time to make your own sweeps with a blanket or heat gun. 3/4" cost's just a little bit more and is way more forgiving to work with.

 

[Norcal]

The extra cost going from 1/2" to 3/4" is not a deal breaker and cheap insurance.

 

[nadogail]

1/2” is the minimum that will work. 3/4” allows for eventful growth.

 

[tarmy]

I always put in an extra conduit iffin’ I went to the effort of digging a trench…and 3/4 would be the minimum…usually I put two 1” or more in open trenches. inevitably, they get used.

 

[rharman]

Having pulled thru 1/2" PVC for just a short (~20') run to put a receptacle on the other side of our front courtyard, I will never use it again.

Well.... I did use it again to house the sensor wires for my garage door opener - up and over the door. Later, I wanted to pull wire from my landscaping timer across the same route and added it to the 1/2". Jeesh, I was kicking myself for having done only the 1/2" but it did get done.

So.... 1/2" PVC for *any* electrical is on my "No Friggin' Way" list.

 

[walrus]

I would never put a piece of 1/2 underground unless it was 10 ft or something. **** ***** if you have to snake it

 

[Red 17]

1 inch would be my choice after struggling with 3/4 and undersizing other more important runs.

 

[ecotec]

If someone told me to pull that wire in 1/2” anything, I would tell them to go **** themselves.

1/2” anything is for sump pumps and furnaces. Anything longer than a stick of 1/2”, should be 3/4”. 1” would be even better.

This is why I don’t do side work.

 

[rjn2649]

I'm going to one up everyone here. You got the shovel in your hand, the trench is dug, TWO, yes two lengths of 3/4, don't know your lay out, but future stuff, security camera, gate opener, car charger....hell, I don't know all kinds of stuff.

 

[mike93lx]

I'm going to one up everyone here. You got the shovel in your hand, the trench is dug, TWO, yes two lengths of 3/4, don't know your lay out, but future stuff, security camera, gate opener, car charger....hell, I don't know all kinds of stuff.

What if you need a car charger and a gate opener at your lamp post?

Three conduits!

 

[ecotec]

I'm going to one up everyone here. You got the shovel in your hand, the trench is dug, TWO, yes two lengths of 3/4, don't know your lay out, but future stuff, security camera, gate opener, car charger....hell, I don't know all kinds of stuff.

On a post light?

 

[sparky 1971]

What if you need a car charger and a gate opener at your lamp post?

Three conduits!

Might as well run a water line while you're at it. Make it two, hot and cold. That would make for a real nice car wash, and since it's at the lamp post, he can wash his car at night. And then put in an empty 3", just for whatever the future might bring.

 

[mike93lx]

Might as well run a water line while you're at it. Make it two, hot and cold. That would make for a real nice car wash, and since it's at the lamp post, he can wash his car at night. And then put in an empty 3", just for whatever the future might bring.

Dont forget data, compressed air and a septic line.

 

[acer66]

Dont forget data, compressed air and a septic line.

and the escape tunnel.

 

[mike93lx]

and the escape tunnel.

4' culvert should give enough to allow all of that

 

[acer66]

4' culvert should give enough to allow all of that

Not with my girth.

 

[mike93lx]

Not with my girth.

Keep it pg13, buddy

 

[yeldogt]

What if you need a car charger and a gate opener at your lamp post?

Three conduits!

It's on the far side of my house near the sidewalk -- helps me cut across the grass when walking the dog. on a corner

 

[yeldogt]

Might as well run a water line while you're at it. Make it two, hot and cold. That would make for a real nice car wash, and since it's at the lamp post, he can wash his car at night. And then put in an empty 3", just for whatever the future might bring.

actually -- do have a hidden outlet for water in a tree pit at that house to clean the street

 

[yeldogt]

On a post light?

Really ..... running the extra wire for an always on outlet is overkill and my guess will never be used.

 

[rjn2649]

ALRIGHT!! point taken, but in my mind I meant so that the extra run could be extended out to a farther point, not necessarily for the light....

 

[Flail]

For all those having problems pushing fish tape into 1/2” pvc conduit, it’s much easier if you use a taper reamer on the male portion of couplers to get rid of the edge that catches the fish tape. Anything more than three bends I use my super flexible wire wound tape, such as the
Greenlee FTFS439-100 Tool, 3/16-Inch X 100-Feet although their are many new nylon/polyester equivalents.