Breaker to subpanel wire gauge step downing...

QuestionEdit

Hi I am an Electronics, IT, and Automotive repair Technician; And have taken on the task of Rewiring some of my home... My Question/Situation is:

I have a 150 Amp Breaker Box Outside and an Old What used to be Fuse Panel inside which prior to my ownership of the home was used as a Tie in area between the original conduit and the Newerish Outside Breaker Box...

I dont like the Idea of Having this Area but it is Required because the living room for instance has 3 separate wire runs of 14/2-Romex -for instance the 1st wire run has 2 outlets on it the 2nd run has 2 switches & 2 lights and the 3rd run has 3 outlets on it- to/from the breaker box I dont want to use 3 Breakers for 1 room.

I have in Place of using Twist caps Installed a 3-port Positive/Hot Distribution Block; but either way my question is;

USING A SINGLE 15 AMP BREAKER WITH 10 or 12 GAUGE WIRE FROM MY BREAKER BOX -outside- TO MY JUNCTION BOX/DISTRIBUTION BLOCK -inside- BE DONE WITHOUT ISSUE..?

I know that going from small gauge wiring to larger gauge wire can cause excessive heat through the smaller wires; But if I use 1 solid 10 or 12 Gauge to feed the 3 Smaller 14 gauge wires will I have a problem or code issue..? Is there any other solution..? Can I "Twist Cap" a Larger Gauge wire from the breaker to the Smaller 14 Gauge ones or does it all have to be 14AWG..?

I also Plan to install a Ground Bus in the Junction panel for the "Bare" ground wires But can I install a Similar Bus rod for the "White" Neutral Wires in the inside junction Panel and Have an 8,10, or 12 Gauge wire feed them from the outside breaker box..?

AnswerEdit

You need to hire an electrician because you have many code and safety issues here. Some electricians will let you help them which help cut costs. But it is worth paying an electrician to come out and look at your situation and steer you in the right direction.