MichelleMcCabe
New User
- Location
- South Africa
- Occupation
- Technology
I would like some feedback on the following information given to me by an electrician regarding our home distribution board installation.
The mains come into the house and into a 50 amp circuit breaker. From there it runs through an earth leakage. From the earth leakage, the wiring runs to the input side of each individual circuit breaker powering various circuits (lights & outlets, water heater, stove, air conditioning etc.) These circuit breakers are rated differently according to their respective load. The smallest circuit breakers are 10A, then there are 20A breakers for the water heater and air conditioning and the biggest one is 40A for the stove.
According to the electrician, ALL of the wires on the INPUT side of the various circuits' circuit breakers must have a current rating of 50A or higher, regardless of the size of the circuit breaker it runs into. According to him, the main circuit breaker (which is rated at 50A) could allow that much current to move across the conductors on the input side of the circuit breakers and if they're not rated for at least 50A, they will burn.
I've done some preliminary searches online to try and determine under what condition this could happen but I'm not sure how to ask this question. As far as I understand it, current is not "pushed" across a conductor, it is "pulled" by a load. Therefore, if I have a 2.5 square mm wire rated for 27A running from the earth leakage to the input side of a 10A circuit breaker that powers some lights, there's no way 50A will ever run through that 2.5 mm conductor. If I connect a 50A load on the output side of the circuit breaker, the breaker itself won't allow that load to pull 50A, it will trip.
Therefore, the only way that 2.5mm wire will have more than 10A running through it, is if the current is "pushed" by some condition from the supply side.
Is this possible? Under what condition can this happen?
I am replacing the wire as per his requirement, but would still like to understand how something like this can happen (if at all).
The mains come into the house and into a 50 amp circuit breaker. From there it runs through an earth leakage. From the earth leakage, the wiring runs to the input side of each individual circuit breaker powering various circuits (lights & outlets, water heater, stove, air conditioning etc.) These circuit breakers are rated differently according to their respective load. The smallest circuit breakers are 10A, then there are 20A breakers for the water heater and air conditioning and the biggest one is 40A for the stove.
According to the electrician, ALL of the wires on the INPUT side of the various circuits' circuit breakers must have a current rating of 50A or higher, regardless of the size of the circuit breaker it runs into. According to him, the main circuit breaker (which is rated at 50A) could allow that much current to move across the conductors on the input side of the circuit breakers and if they're not rated for at least 50A, they will burn.
I've done some preliminary searches online to try and determine under what condition this could happen but I'm not sure how to ask this question. As far as I understand it, current is not "pushed" across a conductor, it is "pulled" by a load. Therefore, if I have a 2.5 square mm wire rated for 27A running from the earth leakage to the input side of a 10A circuit breaker that powers some lights, there's no way 50A will ever run through that 2.5 mm conductor. If I connect a 50A load on the output side of the circuit breaker, the breaker itself won't allow that load to pull 50A, it will trip.
Therefore, the only way that 2.5mm wire will have more than 10A running through it, is if the current is "pushed" by some condition from the supply side.
Is this possible? Under what condition can this happen?
I am replacing the wire as per his requirement, but would still like to understand how something like this can happen (if at all).
