I have buried 1-1/4" conduit from house service panel to garage 26" deep; The conduit does go solid from service panel in basement to sub panel in garage. I am planning on putting in a 100 amp sub panel in garage; I have the permit in hand; I plan to use 2 grounding rods 10' apart with # 6 grounding wire placed in the pole barn/garage. Two questions.. Is it best to use 2-2-4 alum cable to feed the sub panel or use copper? And can I add two runs of 14-3 inside the 1-1/4" conduit to hook up two 3 way switches for a couple of garage lights?

Okay, we need to know the type of conduit along with the conductor sizes to let you know for sure. (RMC - IMC - Sched. 80 PVC - Sched. 40 PVC) The inside diameters are different.

Copper is a better conductor than Aluminum. If you use copper, the size of the conductors will be smaller. However, Aluminum is fine for this application. Remember you must use a four conductor cable from the main service panel to the panel in the garage. (Black - Red - White - Insulated Ground).

At the panel in the garage, Neutral and Ground cannot be bonded together. They
MUST be isolated from each other. They cannot be bonded together at the garage panel!

Also, do not run the 14/3 cables with the feeder to the panelboard. Instead use a panelboard in the garage that will accommodate enough circuits for your need.

The ground rods need only be 8' apart, not 10'.

Thanks for your reply; It is sched 40 pvc; the electrical inspector told me I could run 3 wire through the conduit as long as I put two grounding rods at the garage connected to garage panel with #6 bare copper wire; don't remember what he said about bonding; I was hoping to put the 2 runs of 14-3 from house to garage to connect two 3-way switch circuits to operate two separate lights from house or garage... Would I need to bury another conduit to accommodate the two 3-way switch circuits? And do the 14-3 wires need to be uf if inside conduit?

Sorry, but the electrical inspector is incorrect. Because this is a detached building your are required to do a four wire feed to the panel. See NEC Article 250.32.

I believe the code changed in either 2005 or 2008 mandating that requirement. The grounding system at the garage still has to be there. The ground rods are for protection against lightning.

Thanks Don,
Still, can I put the 14-3 wires in the same conduit for the 3-way switches in the house; I'm not sure how to go about getting the 14-3 romex to the house switches. I thought it would be nice to be able to turn on the outside light from the house. I will go to the 2-2-2-4 .
Thanks again,
Tom

Thanks Don,
Still, can I put the 14-3 wires in the same conduit for the 3-way switches in the house; I'm not sure how to go about getting the 14-3 romex to the house switches. I thought it would be nice to be able to turn on the outside light from the house. I will go to the 2-2-2-4 .
Thanks again,
Tom

You cannot use NM "Non Metallic" cable (Romex) cable in an outdoor conduit. NM cable is listed for "Dry locations" Underground conduit is a "Wet location"

You can use Type UF cable or any of the conductors (individual) that are listed for use in a Wet location. Also, by code, you are required to have a light at the entrance door of the garage which is not the auto doors.

You cannot use NM "Non Metallic" cable (Romex) cable in an outdoor conduit. NM cable is listed for "Dry locations" Underground conduit is a "Wet location"

You can use Type UF cable or any of the conductors (individual) that are listed for use in a Wet location. Also, by code, you are required to have a light at the entrance door of the garage which is not the auto doors.

Don,
Thanks again.. you've been a great help... the light above the entrance door is one that I wish to hook up to a 3 way switch in house, the other 3-way is for the outside light at the peak on the front... I have a 10' carport running the full 48' length of my garage which will have 5 to 6 recessed can lights in the ceiling of the carport... I will plan on using two 14-3 UF and one 2-2-2-4 alum cable...

...the electrical inspector told me I could run 3 wire through the conduit as long as I put two grounding rods at the garage connected to garage panel with #6 bare copper wire; ..It's infuriating when even an inspector does not know what he's talking about.
The ground rods have nothing to do with the ground wire running with the circuit to the sub-panel. You need them regardless if you used to run 3 wires or 4. Now 4 is mandatory.

... the electrical code reference is 250.32(B)(1), with a good exhibit 250.19 in the handbook which shows what Don and Stan have said...

I'm sorry, I misread your switch issue.

Yes, the 14/3 can go into the conduit along with the feeder. Switches only interrupt the ""Hot" leg of the circuit. Also, the code require that a Neutral connection is provided at the switch outlet. There are links on this forum showing you how to wire three way switches.

Two excellent resources for residential wiring (albeit expensive) are "Electrical Wiring - Residential 18th. edition" Ray Mullin & Phil Simmons and "Electrical Systems" by Mike Callanan and Bill "W". Both are based on the 2014 edition of the code. Ray Mullin's book is laid out a little better but either will be great for your use.

I'm sorry, I misread your switch issue.

Yes, the 14/3 can go into the conduit along with the feeder. Switches only interrupt the ""Hot" leg of the circuit. Also, the code require that a Neutral connection is provided at the switch outlet. There are links on this forum showing you how to wire three way switches.

Two excellent resources for residential wiring (albeit expensive) are "Electrical Wiring - Residential 18th. edition" Ray Mullin & Phil Simmons and "Electrical Systems" by Mike Callanan and Bill "W". Both are based on the 2014 edition of the code. Ray Mullin's book is laid out a little better but either will be great for your use.

I have just returned from home depot. I bought a 500' coil of 14 solid to run 6 lines along with the feed; I am planning on putting different colored tape on each run to identify which is which... Is it OK to use the 6 solid IPO the 2 runs of 14-3?; Can I ground the switches in the house to the house service panel ground bar? Or should I go back and get a roll of 14-3 w/grnd? I will use which ever is better... Thanks... Tom

Thanks for your responses... I have run the 2-2-2-4 alum use cable through the conduit with no other wires. I plan to use a wireless 3 way switch for the outside light... thanks.. again... tom