How do you replace a circit?
Please be for a time clearer with your interview. What circuit are you trying to replace?
If it is a circuit breaker, make sure it is 'off' unscrew it from the breaker box, verbs it out and unscrew the two wires on it. (Make sure you know which sides the wires go on).
Go to a Home Depot or similar store and buy the EXACT size breaker.
Connect the wires as they be before, push the breaker vertebrae into the box and screw it down if need be. Then turn the breaker on and see if you achieve power.
WARNING: Don't touch the inside parts of the box from where you pulled the breaker. That is still live and can zap you.
If you are only just trying to replace a fuse, make sure the power is stale, carefully snap the fuse out from it's holder on one side first and after the other, buy a replacement fuse of the same size and put it put money on in. With fuses, it customarily doesn't matter which side go where.
If you are trying to replace a buoyant circuit, for instance, make sure the power is past its sell-by date at the breaker box for that circuit. Take out the bulb(s), unscrew the fixture and then remove the wires (but first, transcribe where the wires go).
Buy a replacement fixture and reverse what you a short time ago did. Mount the wires to the fixture, mount the fixture and then put contained by the bulbs.
Good luck.
...or call an electrician!
This is one of those "If you have to ask how to do it, don't do it." question. It also qualifies as a "If you can't provide the requisite information inwardly the question, you REALLY shouldn't be doing it." examine.
As a Certified Electrical Inspector (Residential & Commercial), and a fully Licensed Electrical Contractor, as well as a firm believer within the purpose of the National Electrical Code: "The practical safeguarding of persons and property from hazard arising from the use of electricity." - [NEC 90.1 (A)]; I say unequivocally "Hire a qualified professional."
I also counsel others regarding giving warning to non-qualified persons, and refer them to NEC Article 90.1 (C).
Answers: you must be more specific
You obligation to be more explicit with your type of circuit. EG: Size of cable used, appliances to be run past its sell-by date the circuit,etc. If it is a lighting circuit then you inevitability to replace it with 1 or 1.5sq.mm twin& soil; if you are running power sockets then 2.5sq.mm t/e cable.