# You asked: How do you measure a breaker for a 3 phase motor?

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## How do you size A circuit breaker for A 3 phase motor?

Breaker size must be rated for a minimum of 125% of the full-load current of the motor it is protecting, rounded up to the next standard breaker size. For example, the full-load current of a 5 HP motor at 460V is 7.6 Amps. The breaker must be sized for 7.6 * 1.25 = 10 Amps .

## How do you size A 3 phase breaker?

For 3-phase loads, you divide the VA by the nominal voltage and by the square root of three (approximately 1.732). If your total 3-phase load in a 480V system is 50,000VA, what size breaker do you need? 50,000VA ÷ (480V × 1.732) = 60.2A. The next size up is 70A.

## How do you determine the size of A motor circuit breaker?

You must size the overloads no more than 115% to 125% of the motor nameplate current rating, depending on the conditions [430.32(A)(1)]. You must size the short-circuit ground-fault protection device from 150% to 300% of the motor FLC [Table 430.52].

## How do you select A circuit breaker for A motor?

How to choose a motor circuit breaker?

1. Long delay current setting value—motor rated current.
2. Instantaneous setting current. …
3. The returnable time of the 6 times long delay current setting value ≥ the actual starting time of the motor.
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## What size breaker do I need for a 3 HP motor?

A 3 HP will be about 18amps. the circuit breaker for the 13 amps should be 20 amps. For the 3 HP the breaker should be 30 amps .

## What size breaker do I need for a 15 amp motor?

A 12 wire and a 20A breaker is needed. 15A ends can be used on 20A circuits.

## How many amps is A 3 phase?

The average voltage is 453 plus 458 plus 461 divided by 3 which equals 457 volts. The average current is 14.1 plus 13.9 plus 13.8 divided by 3 which equals 13.9 amps.

## How do I select A circuit breaker?

Selection of rated circuit breaker

1. What is the task of the branch circuit or feeder?
2. Which rated current / setting range?
3. Breaking/making capacities / rated operational voltage?
4. Any special requirements?
5. Which type of co-ordination?
6. What is the mode of mounting?
7. Cross-section of the connecting wire/cable?

## What is the standard circuit breaker size?

The standard for most household circuits are rated either 15 amps or 20 amps. An important note to remember is that circuit breakers can only handle about 80% of their overall amperage. That means a 15-amp circuit breaker can handle around 12-amps and a 20-amp circuit breaker can handle about 16 amps.

## How do you measure breaker size in A group of motors?

Calculating the circuit breaker size for group of motors

⇒ (1.75 x 7.6) + (2 x 4.8) + (5 x 3.4) = 39.9 A.

## How do you size A circuit breaker pump?

So you’ve to choose breakers according to the amperage of the pump. For example, a 0.5 HP well pump uses around 7 amps to operate properly. So, it requires a 15 amp circuit breaker. So, installing a circuit breaker that has 2x more amp capacity is a safe play.

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