conduit size?

[jpcjguy]

Hi all,

So I have started on the garage build and going to run 125A into the garage from the house. it is about 260 feet from garage. On the chance, I might need more, I figure it is cheap insurance to run a slightly bigger conduit. What would the conduit size be for 200A vs 125A for that run?

thanks!

 

[jaygill]

At 125 amps you’d normally use 1 gauge THHN which can carry 130 amps but based on distance you’re going to go up a size to minimize voltage loss so that is 1/0 THHN.
Cross referencing the pvc conduit fill chart the first size that will carry at least 2 1/0 gauge conductors plus ground is 1 1/4” Schedule 40. Schedule 80 you need 1 1/2”. To future proof yourself for 200amps you’re going to use 4/0 wire. Both Sch 40 or Sch 80 conduit requires 2”



Ampacity chart:

cerrowire.com/products/resources/tables-calculators/ampacity-charts/


PVC Conduit fill table:
elliottelectric.com/StaticPages/ElectricalReferences/ElectricalTables/Conduit_Fill_Table_PVC.aspx#1/0-3/0


Sent from my iPhone using Tapatalk

 

[jpcjguy]

Thanks!

So based on that chart I can use 1/2 schedule 40 for 3-way wire to control the outdoor lights from the house. I figure 12 gauge would be fine for that run...

 

[exranger06]

At 125 amps you’d normally use 1 gauge THHN which can carry 130 amps but based on distance you’re going to go up a size to minimize voltage loss so that is 1/0 THHN.
Cross referencing the pvc conduit fill chart the first size that will carry at least 2 1/0 gauge conductors plus ground is 1 1/4” Schedule 40. Schedule 80 you need 1 1/2”. To future proof yourself for 200amps you’re going to use 4/0 wire. Both Sch 40 or Sch 80 conduit requires 2”



Ampacity chart:

cerrowire.com/products/resources/tables-calculators/ampacity-charts/


PVC Conduit fill table:
elliottelectric.com/StaticPages/ElectricalReferences/ElectricalTables/Conduit_Fill_Table_PVC.aspx#1/0-3/0


Sent from my iPhone using Tapatalk

You need to run 4 conductors to feed a subpanel, not 3.

 

[MattT]

What would the conduit size be for 200A vs 125A for that run?

Here's what I figured keeping volt drop under 3%. And personally I'd go up a size on the conduit to make the pull easier.

Copper:

125A 2/0 Wire 1 1/2" Conduit.
200A 250 kcmil Wire 2" Conduit.

Aluminium:

125A 250 kcmil Wire 2" Conduit.
200A 500 kcmil Wire 2 1/2" Conduit.

 

[sberry]

Use 2.

 

[Jim greengo]

I wouldn't use anything smaller than 2"

 

[u2slow]

I wouldn't use anything smaller than 2"

Same. That's a long run.

 

[Innovate1]

Having done a 40' run of 3/4" sch 40 PVC with two 90s with 3 strands of #6 and can't recall what size the 4th ground wire was. 4 strands of #6 is right at the limit per the table for fill. I can tell you it was a difficult pull. Up size the conduit at least one size to make the pull easier, especially for longer runs.

On a related note - what is recommended size for 2-2-2-4 MHF for 80' run to garage sub panel? Will have two 90s - one at each end. 1-1/4 meets the fill but I figure I should go with AT LEAST 1-1/2 (sched 40) to make the pull easier. And if I ever have to pull it out - hopefully I won't every have to do that.

 

[sberry]

It needs every bit of 1.5.

 

[mm08822]

At 125 amps you’d normally use 1 gauge THHN which can carry 130 amps but based on distance you’re going to go up a size to minimize voltage loss so that is 1/0 THHN.
Cross referencing the pvc conduit fill chart the first size that will carry at least 2 1/0 gauge conductors plus ground is 1 1/4” Schedule 40. Schedule 80 you need 1 1/2”. To future proof yourself for 200amps you’re going to use 4/0 wire. Both Sch 40 or Sch 80 conduit requires 2”

Ampacity chart:

cerrowire.com/products/resources/tables-calculators/ampacity-charts/

PVC Conduit fill table:
elliottelectric.com/StaticPages/ElectricalReferences/ElectricalTables/Conduit_Fill_Table_PVC.aspx#1/0-3/0

Sent from my iPhone using Tapatalk

OP would go broke running 4 cu conductors 260'.

 

[mm08822]

Thanks!

So based on that chart I can use 1/2 schedule 40 for 3-way wire to control the outdoor lights from the house. I figure 12 gauge would be fine for that run...

12's will only be good for a 1 amp load. You will have 3x 260' = 780' of wire in that ckt. Have the 3ways drive an ice cube relay in the garage. Then the load won't matter.

I would use 3/4" conduit minimum. 1" = better.

 

[MattT]

12's will only be good for a 1 amp load. You will have 3x 260' = 780' of wire in that ckt. Have the 3ways drive an ice cube relay in the garage. Then the load won't matter.

I would use 3/4" conduit minimum. 1" = better.

Only 2 of the 3 conductors will be carrying current. #12 should be good for about 3 amps which is a lot of LED lighting.

Or if the shop is gonna have internet one of those smart switches would probably be cheaper than wire & pipe........................

 

[jpcjguy]

Thanks for all the feedback everyone! I will only pull wire for 125A but will size for 200A in the conduit - anything to not have to dig again! I doubt I will need more than 125A, but cheap insurance to go with a 2.5" pipe. As for other pipes, maybe two 1" pipes- one for coax/internet and one for either the 12 gauge for the 3-way switch (but as MattT stated, maybe go with a smart switch setup for the outdoor lights).....
Anything else I might want to run/throw into the trench???

 

[mike93lx]

Thanks for all the feedback everyone! I will only pull wire for 125A but will size for 200A in the conduit - anything to not have to dig again! I doubt I will need more than 125A, but cheap insurance to go with a 2.5" pipe. As for other pipes, maybe two 1" pipes- one for coax/internet and one for either the 12 gauge for the 3-way switch (but as MattT stated, maybe go with a smart switch setup for the outdoor lights).....
Anything else I might want to run/throw into the trench???

Water, gas, air compressor line, hookup for portable generator

 

[Innovate1]

If you can I would separate the low voltage (internet, etc) from the power run by a foot or two. Smart to put in the third conduit for the 3 way even if you don't use it now. You may have need of it later. And going 1" is also smart as it costs very little more than 3/4. You may even want to go to 1-1/4. Digging in more later is a lot of work.

 

[sberry]

Future proof strikes again. What is the real possibility of needing above 125A? I been doing this a while, never had to upgrade a feed like this.

 

[tjansson]

I recently pulled 2 ga AL XHHW, 4 wires, through 2" without much issue, all by hand. Both runs were about 110 ft with 2x 24" radius 90 deg sweeps and 1x 36" 90 deg. Serving 100a subpanels.

Be careful with what size you select, I found it difficult to source 24" and 36" radius bell end sweeps in 2.5" and 1.5". 2" and 3" are easier to find.

Planning on using 2.5" for burying my 200a feeder to my house. 60 ft with 3x 90 sweeps.

2 ga aluminum is pretty cheap if you are OK with 100a at the garage.... 500 ft for $150 at the box stores.

 

[mm08822]

Only 2 of the 3 conductors will be carrying current. #12 should be good for about 3 amps which is a lot of LED lighting.

Or if the shop is gonna have internet one of those smart switches would probably be cheaper than wire & pipe........................

Woops....only 2 conductors in use. 3a does give more headroom. Still need to know the load to be sure.

 

[mm08822]

I recently pulled 2 ga AL XHHW, 4 wires, through 2" without much issue, all by hand. Both runs were about 110 ft with 2x 24" radius 90 deg sweeps and 1x 36" 90 deg. Serving 100a subpanels.

Be careful with what size you select, I found it difficult to source 24" and 36" radius bell end sweeps in 2.5" and 1.5". 2" and 3" are easier to find.

Planning on using 2.5" for burying my 200a feeder to my house. 60 ft with 3x 90 sweeps.

2 ga aluminum is pretty cheap if you are OK with 100a at the garage.... 500 ft for $150 at the box stores.

#2 AL will only provide 90a . Less if long distance.

 

[Innovate1]

I have only used standard radius sweeps in the past but see that larger sweeps are available from electrical supplies (as opposed to big box stores). What's the general rules of thumb of when a larger sweep should be used?

Looking at 80' run of 2-2-2-4 MHF or perhaps single strands of same size with two 90s. Planned to go with at least 1.5" and maybe 2"

 

[ard]

Consider a 1.5" conduit for a fiber. While the fiber is small, typically you will pull it with terminations on the end of the fiber- a big hole will make it super easy.

(I'm facing a 300 ft run in 3/4".... Need to find someone to field terminate fibers... )

 

[tjansson]

#2 AL will only provide 90a . Less if long distance.

I actually used 2 ga XHHW-2, which according to the cerrowire chart, is good for 90 deg C and 100a. I could be missing something though.

Can't link the chart with my post count... just google "cerrowire ampacity".

 

[Innovate1]

Radius is also an issue with fiber although I was thinking of wire...

 

[tjansson]

I have only used standard radius sweeps in the past but see that larger sweeps are available from electrical supplies (as opposed to big box stores). What's the general rules of thumb of when a larger sweep should be used?

Looking at 80' run of 2-2-2-4 MHF or perhaps single strands of same size with two 90s. Planned to go with at least 1.5" and maybe 2"

I thought the rule of thumb was to use big ones whenever possible. The Vermont utility installation manual specifies 36" radius for vertically installed 90s and 48" radius 90s for horizontal 90s, for underground service. Not sure if anyone actually follows that on customer-owned equipment, since trench inspections are not required in most of the state.

 

[mike93lx]

I actually used 2 ga XHHW-2, which according to the cerrowire chart, is good for 90 deg C and 100a. I could be missing something though.

Can't link the chart with my post count... just google "cerrowire ampacity".

Can't use 90C chart.

The limit is 90A except for some exception when it is feeding the entire load of a residential building (IIRC)

 

[Innovate1]

Found this table of standard radius of PVC sizes. The radius are pretty small. I can see how going with a larger radius would make things a lot easier.

http://www.alliedeg.us/pvc/pvc-elbows-standard-radius/

 

[Tduby]

Except to remote lights I don’t burry less than 2” between buildings it’s hardly any price difference and frankly for future expansion who knows what the next must have technology will be and conduit size it will need.

 

[jpcjguy]

So my footer is poured and block is done, so I have a better idea of my run. With slack built in, I am at 230 feet. So I am thinking actual length is 215-220. I think copper is out of my budget so it will be aluminum wire. So 2" or 2.5" conduit to support 200A using aluminum?

 

[mike93lx]

So my footer is poured and block is done, so I have a better idea of my run. With slack built in, I am at 230 feet. So I am thinking actual length is 215-220. I think copper is out of my budget so it will be aluminum wire. So 2" or 2.5" conduit to support 200A using aluminum?

I think that would require 350MCM... You're talking about a lot of wire and I wouldn't want to have to pull what you are running now for 125a and then rebuy such expensive wire. I would really think about what you need and do it once.

 

[MattT]

With slack built in, I am at 230 feet. So I am thinking actual length is 215-220.

Is that including the verticals at each end of the run?

I think that would require 350MCM.

350MCM is good for 234'.

 

[jpcjguy]

That does include the verticals. I rather err on the higher side to be safe, that is why I am thinking the actual is around 215-220.

 

[wyliesdiesels]

Why do you need 125’?

What are you running in there? Single man shop?

 

[TTMotorsports]

I just did this on my shop. 250ft. 2 1/2 in conduit. 250 mcm wire 4/0 ground.

I'm running 125amp but sized for 200amp in future as well.

I believe fill chart shows 2inch but I had a hell of a time pulling it through 2 1/2 with only 1 45deg bend in it.

 

[jpcjguy]

Why do you need 125’?

What are you running in there? Single man shop?

Continuous (i.e. uncontrolled loads - not sure when running) and (known "on" like lights, stereo)
Up to two mini-splits (attic room area and downstairs)
Full size fridge
Stereo
Lights
220v air compressor (not sure when it will kick on)
6 gallon water heater for half bath

Controlled loads (meaning a person has complete control of usage)
10k lift
220 mig welder
Plasma cutter
Drill Press
various saws (table, chop, etc.)
various hand tools - grinders, etc.

Currently it is just me (and friends) and soon my sons (almost 10) working in it. My unknowns are what size mini-splits I am going to use (down the road), what full size fridge (to be purchased), which water heater.

 

[jpcjguy]

I just did this on my shop. 250ft. 2 1/2 in conduit. 250 mcm wire 4/0 ground.

I'm running 125amp but sized for 200amp in future as well.

I believe fill chart shows 2inch but I had a hell of a time pulling it through 2 1/2 with only 1 45deg bend in it.

Thanks for the info! Can you let me know how you did you load calculations?

 

[TTMotorsports]

I just asked an electrician what size wire I needed for 200 amp and he told me. Then I ran a 125amp breaker on house panel. Figured if that pops or the main 200amp breaker feeding house pops I'll upgrade entire thing to bigger panel. So far no problems with the following
Qty 2. 5 ton ac units. Mig welder. Cnc plasma cutter. 2 2 post lifts. 10hp air compressor. 10hp rotary phase converter for mill and iron worker. Lots of equipment and 2 people working and no issues yet.

 

[mike93lx]

I just asked an electrician what size wire I needed for 200 amp and he told me. Then I ran a 125amp breaker on house panel. Figured if that pops or the main 200amp breaker feeding house pops I'll upgrade entire thing to bigger panel. So far no problems with the following
Qty 2. 5 ton ac units. Mig welder. Cnc plasma cutter. 2 2 post lifts. 10hp air compressor. 10hp rotary phase converter for mill and iron worker. Lots of equipment and 2 people working and no issues yet.

Interesting because 250mcm is too small for a 200a load, at least within the standard <3% voltage drop. It is certainly enough for the 125a that you have it breakered at now though

 

[TTMotorsports]

Interesting because 250mcm is too small for a 200a load, at least within the standard <3% voltage drop. It is certainly enough for the 125a that you have it breakered at now though

Voltage drop: 6.54
Voltage drop percentage: 2.73%
Voltage at the end: 233.46

That is what the calculators came up with for me. But I'm definitely not a pro so may be wrong. But the Inspector said that it was all good for 200 amp service upgrade.

 

[wyliesdiesels]

I just asked an electrician what size wire I needed for 200 amp and he told me. Then I ran a 125amp breaker on house panel. Figured if that pops or the main 200amp breaker feeding house pops I'll upgrade entire thing to bigger panel. So far no problems with the following
Qty 2. 5 ton ac units. Mig welder. Cnc plasma cutter. 2 2 post lifts. 10hp air compressor. 10hp rotary phase converter for mill and iron worker. Lots of equipment and 2 people working and no issues yet.

The electrician obviously didnt factor in voltage drop or you didnt tell him the wire length. 250McM AL is good for 205a WITHOUT factoring voltage drop.

So you ran the wrong size wire for 200a.

Voltage drop: 6.54
Voltage drop percentage: 2.73%
Voltage at the end: 233.46

That is what the calculators came up with for me. But I'm definitely not a pro so may be wrong. But the Inspector said that it was all good for 200 amp service upgrade.

what calculator did you use?

i usually do the calcs by hand but even the southwire calculator(which can inflate the numbers and/or have wrong values for resistance; my guess- they do it to sell more larger wire) says you need 400Kcmil AL.

What does a service upgrade have to do with a feeder to a detached structure?

EDIT: did the calcs by hand

250Mcm gives 3.9% drop
300Mcm gives 3.4% drop
350Mcm gives 3% drop

So how did you come up with 2.73% drop with Al 250Mcm?