I am currently putting in a patio and walk way. I have some hope of adding a detached garage in the future so I am burying conduit under the walk way for future use. I would like 220v in the garage for welding and a compressor. I estimate a maximum of 150 feet of cable from my curent house panel to the garage. What is a suffcient conduit size? 1.5? In The State of Rhode Island and Providence Plantations.
Conduit size
- Thread starter M_J
- Start date
conduit size dependents on the number of wires and the size/type of wire you are choosing... There is an app for that on android, probably one for iphone as well.
I fit 6 #6 wires on a 1.5 Rigid conduits for about 200 feet and its fine until I have a section with too many 90 deg (3 of them) too close to each other.
I fit 6 #6 wires on a 1.5 Rigid conduits for about 200 feet and its fine until I have a section with too many 90 deg (3 of them) too close to each other.
rockwithjason
Well-known member
1 1/2 is the minimum I would use. I would probably go 2 in for myself. you could bury a sleeve under the sidewalk and then push a pipe thru it later. get a chunk of 3 in or something and tape up the ends and bury it 2 ft down. then you can push what ever you want at a later time
Stuart in MN
Well-known member
You may want to put a couple conduits in - one for power, and one for low voltage stuff, like telephone/internet/security system/etc.
sberry
Banned
2 inch.
Eriehunter
Well-known member
- Joined
- Mar 14, 2014
- Messages
- 189
Depends on how much power you want out there but I would go 1 1/2" for 100 amp or 2" for 200 amp. Most places 100 amp is more than enough.
Also plan for waterlines, sanitary, gas and phone/data, spare depending on your future expectations.
Also plan for waterlines, sanitary, gas and phone/data, spare depending on your future expectations.
alfredeneuman
Well-known member
The price difference between 1-1/2" and 2" is about $1.25 per 10' length. It would add less than $20 to the price.
I vote for 2"
I vote for 2"
pattenp
Well-known member
Another vote for 2".
Edit: Just in case you don't know the depth requirements, in your case the NEC required cover for PVC conduit is 18 inches.
Edit: Just in case you don't know the depth requirements, in your case the NEC required cover for PVC conduit is 18 inches.
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AP514
Well-known member
I would just put in a few 2"-3" pipes and cap them off..maybe a 1 1/2 too you never know what you will add later. i did that for my driveway...so happy i did when i added a sprinkler system and a then a Garage
Thanks for the input. I ended up burying 4 inch schedule 40 water pipe and when the needs of the garage are determined I will run the appropriate electrical conduit.
I really dont even want to think of a garage right now. I'm doing all the work on this patio project and I am beat.
I really dont even want to think of a garage right now. I'm doing all the work on this patio project and I am beat.
Mustang51js
Well-known member
Just so you know a 2 1/2 inch would handle 200 amps which would be plenty more than you would need
Quijote
Well-known member
The electrician who ran 100A/220V to my garage 100' away used at least 2", but off the top of my head it seems more like 2.5".
He used a pretty beefy cable. Pretty sure it is 4AWG.
He used a pretty beefy cable. Pretty sure it is 4AWG.
alfredeneuman
Well-known member
A 2" conduit could be used for a 200 Amp circuit. The price of the conduit goes up drastically between 2" and 2-1/2" .
Quijote, Are you sure you mean #4, and not 4/0?
jdwilson44
Well-known member
Yes - power and "low voltage" - should not travel in the same conduit. They shouldn't actually even travel right next to each other. There's supposed to be a distance between them (to avoid interference issues) - and if you have to cross them it's supposed to be at a 90 degree angle if I remember correctly.
Conduit is also supposed to be buried in sand - there's supposed to be some minimum amount of sand surrounding the buried conduit. I believe this is for drainage issues as well as avoiding things like rocks puncturing the conduit at some point down the road. Depending on your area of the country - the ground freezes and things move around under the ground. A rock that is contacting a piece of conduit directly may move around enough over many freeze/thaw cycles to work it's way thru the conduit.
Joints will also leak under the ground . I'm sort of **** - so what I did when I buried conduit from my house out to my garage - was I wrapped the conduit in Grace Bituthene (foundation waterproofing membrane) - to help seal it against water intrusion. Especially around the joints. The stuff has been in there for about 5 years now - and so far at least there has been no water intrusion that I know of.
pattenp
Well-known member
I'll say... conduit will get moisture in it overtime just from condensation. You wasted time and money doing what you did. Was the sand a local requirement? I have never heard of electrical conduit being required to be installed in sand when buried.
I will say that too, water always finds it way into stuff installed outside. In the conduit it's fine, doesn't hurt. In things like bell boxes, I drill weep holes so it has a way to get out.
jdwilson44
Well-known member
True - it will get condensation in it - and I knew that when I did it. The intent was to avoid any possibility of ground water getting in. I know what the water table is like on my property - especially in the spring - and I knew that the conduit would be exposed to a high water table at certain points of the year. I also buried it deep - like 2.5 - 3ft, partially because of the way it had to run and partially to get it down below the frost line as much as I could.
Condensation also tends to form when you have big temperature differences. The deeper you go underground the less the temp fluctuation. Then you just have to worry about sealing up the ends so moist air doesn't get in there in the first place.
As far as being a time and money waste - I wanted to be as sure as I could that the thing wouldn't leak. Digging it up later because some joint is leaking - costs a hell of a lot more in time and money than over-doing it the first time.
I don't remember where exactly where I read about burying in sand - it's been a few years since I did this , but a quick search showed plenty of hits on code requirements about burying cables in sand if they are direct burial. I also found a few hits on burying conduit in sand. I'm in New England - I can tell you for a fact that the soil here is FULL of rocks (I've done quite a bit of digging in it) - and burying soil full of rocks right up against a conduit just doesn't seem like a good idea anyway - to my way of thinking at least.
Around here - it ***** bad enough to have to dig the trench in the first place - it ***** even worse to have to dig it up and do it again. The OP is in Rhode Island - he's going to have similar soil conditions to what I've got up here in MA.
jdwilson44
Well-known member
There's a conduit fill chart on this page:
http://www.constructionmonkey.com/calculations/electrical/tables/conduit
If in doubt - go bigger. The codes basically state you can only put so much wire in a certain sized conduit. This is supposedly to avoid overheating issues from what I remember reading at some point in the past. So - if you have any doubt - go bigger. If you go too small you're going to be restricted on how much wire you can fill that conduit with and you may find you just restricted yourself to a 100 amp service when you really wanted a 200 amp service run out to that garage.
Without consulting the actual NEC or talking to an actual electrician though - take internet information with a grain of salt.
Also be aware that the larger you go - the easier it will make pulling the cable thru when that day finally comes.
If you've got to change directions - make sweeping bends not corners.
http://www.constructionmonkey.com/calculations/electrical/tables/conduit
If in doubt - go bigger. The codes basically state you can only put so much wire in a certain sized conduit. This is supposedly to avoid overheating issues from what I remember reading at some point in the past. So - if you have any doubt - go bigger. If you go too small you're going to be restricted on how much wire you can fill that conduit with and you may find you just restricted yourself to a 100 amp service when you really wanted a 200 amp service run out to that garage.
Without consulting the actual NEC or talking to an actual electrician though - take internet information with a grain of salt.
Also be aware that the larger you go - the easier it will make pulling the cable thru when that day finally comes.
If you've got to change directions - make sweeping bends not corners.
Underground conduits are going to get water in them & they are defined as a wet location by the NEC, as long as the proper conductors are used there is no problem.
jdwilson44
Well-known member
Posted a question on another forum I go on that I know has a number of electricians on it. I asked what conduit size would be needed for a 200 amp service - on the premise that if you wanted to REALLY go full out you'd likely want that - and here's the answer I got back from one guy whom I know is an electrician:
I didn't even think about the copper vs. aluminum wiring thing. But it's good to bear in mind - since aluminum wiring is probably significantly cheaper than copper - and the OP's estimate was for 150 feet. So you can save money on the wiring - but you're going to need a bigger conduit to put it in - which will cost you more.
In any case - it sounds like a 3" conduit will likely cover any eventuality of wiring type or feed size you might want to put out to that garage. Going smaller might restrict you to what size feed you can run or which wire type you can use depending on the feed you want to run.
I didn't even think about the copper vs. aluminum wiring thing. But it's good to bear in mind - since aluminum wiring is probably significantly cheaper than copper - and the OP's estimate was for 150 feet. So you can save money on the wiring - but you're going to need a bigger conduit to put it in - which will cost you more.
In any case - it sounds like a 3" conduit will likely cover any eventuality of wiring type or feed size you might want to put out to that garage. Going smaller might restrict you to what size feed you can run or which wire type you can use depending on the feed you want to run.
Mustang51js
Well-known member
I figured 2 1/2 because I know for underground you need the next size up in a service,not sure if that applies to sub panels but then you have the extra wire also and figure on aluminum. Plus didn't have my book to check so didn't want to say to small because I don't know off top of my head how many #1 al you can put in a 2 inch
alfredeneuman
Well-known member
jd:
The NEC Table shows that as many as (5) 3/0 THWN will fit in a 2" Sch40 Conduit.
There would be only 3 of them with a #6 Cu ground.
(There are several full time electricians here, too.)
The NEC Table shows that as many as (5) 3/0 THWN will fit in a 2" Sch40 Conduit.
There would be only 3 of them with a #6 Cu ground.
(There are several full time electricians here, too.)
If you want to oversize then use EUSERC standards, 3 inch, for 100A, or 200A, UG services.
PG&E uses EUSERC standards.
All jokes aside, if the run is straight 1 1/2" would be fine even if 100A was chosen.
Mustang51js
Well-known member
It's more of a local thing,above ground service I can use 2 inch for 200 amp but have to use 2 1/2 inch for underground,power co says they override local inspectors.
jdwilson44
Well-known member
Isn't there a difference between "fit" and "acceptable"?
I seem to remember reading something in the past that the fill ratios were there to prevent overheating of the wires within the conduit. Although like everything the devil is in the details - so I can see how the fill ratio for PVC conduit buried underground would differ from say a metal conduit run within a building.
Mustang51js
Well-known member
Misread
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On the subject of water in conduit: I use to build pools and we ran pvc conduit for the lights. This is a wet pipe and we glued it the same as the schedule 40 for the pump lines, primer and glue. The only time we had a problem was from a temp fence post being driven in to one.
The inspectors pass it but still has to meet PoCo standards, they still have the ultimate say, they don't like it, you don't get power. It does not matter to the OP unless he is going to have a separate service though, as most of the PoCo rules end at their cash register (meter).
rburke65
Well-known member
I ran 2" ........
sberry
Banned
I ran some 1.5 for similar runs, if I had to do it again it would be 2.