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Fuse sizing is calculated by the size of the conductor. The conductor is calculated by the amperage to the load.

The above answer is partially right, however in calculating fuse sizes for say a motor load of 10 hp on 208 volts 3 phase. The table in 430.250 list this motor as pulling 30.8 amps. Conductor size would be 30.8 times 1.25 or 38.5 amps. This value would lead you to wire table 310.15(B)(16) and a conductor size of number 8THWN. This conductor is listed for 50 ampacity, however due to the starting current of the motor. A fuse could be sized at 30.8 times 1.75 or 53.9 amps. The next standard size would be 60 amps. the fuse size is above what the conductor is rated for, but because of motor overload protection the conductor is protected. If breakers were used instead of fuses, a breaker would be sized at 30.8 times 2.5 or 77 amps or 80 amp next standard size.

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12y ago
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2w ago

To calculate the main fuse size for electrical wiring, you need to determine the total current drawn by all the circuits connected to the main fuse. Add up the current ratings of all the devices (appliances, lights, etc.) on the circuit. The main fuse should be rated slightly higher than the total current to ensure safety and prevent nuisance tripping. It is recommended to consult a qualified electrician for accurate calculations.

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12y ago

It needs to match the rating of the service and the panel itself. The panel will have an amperage rating and you should not exceed this.

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Q: How do you calculate the main fuse for electrical wiring?
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MSB stands for Main Switchboard. It is a panel that serves as the primary distribution point for electrical power in a building or facility. It typically contains main circuit breakers and is where all incoming electrical power is distributed to various circuits.


How is godown wiring different from hostel wiring?

Godown wiring refers to the electrical wiring system in a storage facility typically designed for efficient lighting and power supply to large spaces. Hostel wiring refers to the electrical wiring system in a residential building that accommodates multiple occupants, with individual rooms or living units having their own wiring for lighting, power outlets, and other electrical needs. The main difference lies in the scale and complexity of the wiring design to suit the specific usage requirements of each type of building.


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Mains sockets are electrical outlets designed to connect devices to the power supply. They provide access to electricity for devices such as lamps, appliances, and chargers. Mains sockets are typically found in homes, offices, and public spaces for powering various electrical devices.


What color is the neutral lead?

In electrical wiring, the neutral lead is typically color-coded as white or gray. It is used to carry current back from electrical devices to the main power source.


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Parallel for main circuits and series parallel for lighting circuits.

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How is godown wiring different from hostel wiring?

Godown wiring refers to the electrical wiring system in a storage facility typically designed for efficient lighting and power supply to large spaces. Hostel wiring refers to the electrical wiring system in a residential building that accommodates multiple occupants, with individual rooms or living units having their own wiring for lighting, power outlets, and other electrical needs. The main difference lies in the scale and complexity of the wiring design to suit the specific usage requirements of each type of building.


What are mains sockets?

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What color is the neutral lead?

In electrical wiring, the neutral lead is typically color-coded as white or gray. It is used to carry current back from electrical devices to the main power source.