Another "what size wire" question

[ottsville]

Been looking at calculators and searching this forum most of the morning and my head is spinning.
I have a new detached garage that will have a 100 amp subpanel in it. The garage panel is approx 130' from the house panel, so with risers at both ends let's call it 150'. Wire will be run in conduit and buried 18".

I got a quote for 1800 to run the wire and make all the connections. Considering running it myself (should save about 1k). Electrician quoted based on #3 THHN x 3 and a #8 ground. All the calculators I'm using(maybe I'm doing it wrong) call for #2 or #1. What is correct?

Garage has 4 circuits, 1 30amp rv outlet, 1 15amp of lighting(led shop lights and exterior lighting) and 2 20amp outlet circuits.

 

[marklc]

I'd go at least #2 or go with #1 if your concerned about voltage drop at all. But at 150' I think you'll be ok with #2. I'd probably up the ground to a #6 also JMO.

 

[sberry]

You can use number 2 alum and feed it with a 60, this gives good solid service for garage loads of this nature and V drop isn't an issue. Wire about a buck and a half a foot. Breaker 10 or 15$

 

[pattenp]

When talking about wire size make sure you state if aluminum or copper. #3 is probably copper vs. #2 or #1 being aluminum.

 

[matt_i]

Personally I'd buy enough 2" PVC conduit, some sweeps and LBs, rent the trencher, call miss dig, and have a 500ft spool of #2 THHN/THWN copper and a #6 bare ready to go.

 

[theoldwizard1]

You can use number 2 alum and feed it with a 60, this gives good solid service for garage loads of this nature and V drop isn't an issue. Wire about a buck and a half a foot. Breaker 10 or 15$

To restate what sberry said, if you limit the feed to 60A (which is more than enough for 98% of the one-man shops in existence) you can use #2 aluminum wire, like 2-2-2-4 HF, and save a LOT of $$$ !

Keep the 100A box if you want to connect a lot of circuits. Many heavy loads need a separate circuit per load, but are not likely to be run at the same time (welder and a table saw).

 

[wyliesdiesels]

#3 THWN cu or #1 AL will work at those distances for 100a.

Use #8 cu or #6 AL for the EGC.

Make sure to isolate the neutral bar in the subpanel. U may need a ground bar kit.

Also need 2 ground rods.

 

[ottsville]

Thanks guys.

Ground rods already installed and neutral is isolated.

 

[revamped]

Dude, its exactly what I just did. I ran 125ft of 2-2-2-4 AL MHF in 2" PVC from the house to the panel location and everything cost me about $400. I ran it 36" underground due to driveway and I buried it with low voltage 1" conduit, my water line and my gas line.

Check out the pics in my build. I plan on a 90A at the house for the feed and a 100amp panel in the garage with as many circuits as I can buy. I have 2 ufers in the foundation. still planning out my circuits and getting ready to wire.