I have a customer with a detached garage/shed unit that wants to install a few outlets and light fixtures/recessed lighting - common residential use, meaning no heavy power tools, washers/dryers, etc.
The CLOSEST power supply to the unit is 8 AWG wire rated for 40A-- which is coming from a 40A breaker in the panel. This breaker previously powered an outdoor spa. The wire is run via underground conduit out to the original spa location -- which has since been removed. The conduit opening is about 6 feet away from the garage.
My initial plan was to swap the 40A breaker in the panel to 15A or 20A and pull out the 8 gauge wire entirely and swap it with 14 AWG or 12 AWG. From there, I would extend the conduit to the garage and wire up the receptacles and lights from there.
The customer wants to know WHY we can't just simply "tap into" or use the end of the existing conduit run with 8 AWG as a junction point for the 14/12AWG that will run into the garage.
Besides always wanting to matching the wire gauge EXACTLY to the breaker I have in the panel -- I didn't have a good response. Obviously running NEW matching wire adds more to his cost -- so I want to be sure there is a technical standard I'm meeting by pushing for doing this.
What options do I have here? Or is the customer correct?