This Power Point Calculator helps you determine if your electrical circuit can safely handle the appliances you plan to plug in. Overloading a single power point or circuit is a leading cause of electrical fires and tripped breakers.
Key Electrical Terms
Watts (W): The measure of total power consumed by the appliance.
Volts (V): The electrical potential of your home (usually 120V in the US or 230V in most other regions).
Amps (A): The flow of electrical current. Circuit breakers are rated in Amps.
The 80% Rule
In electrical engineering, it is recommended that a circuit's "continuous load" (items running for more than 3 hours) should not exceed 80% of the circuit breaker's capacity. For example, on a 15A breaker, you should ideally only draw 12A of continuous current.
Example Calculation
If you have two heaters rated at 1500W each on a 230V system:
Total Watts: 1500W x 2 = 3000W
Total Amps: 3000W / 230V = 13.04 Amps
If your circuit breaker is 15A, 13.04A is within the limit, but exceeds the 80% safety margin (12A). It is safer to move one heater to a different circuit.
function calculateLoad() {
var watts = parseFloat(document.getElementById('applianceWatts').value);
var qty = parseFloat(document.getElementById('applianceQty').value);
var voltage = parseFloat(document.getElementById('systemVoltage').value);
var breaker = parseFloat(document.getElementById('breakerAmps').value);
var resultsDiv = document.getElementById('powerResults');
var totalWattsElem = document.getElementById('totalWattsResult');
var totalAmpsElem = document.getElementById('totalAmpsResult');
var warningElem = document.getElementById('loadWarning');
if (isNaN(watts) || isNaN(qty) || isNaN(breaker) || watts <= 0 || qty breaker) {
warningElem.innerHTML = "⚠️ DANGER: Circuit Overloaded! The current draw (" + totalAmps.toFixed(2) + "A) exceeds your breaker capacity (" + breaker + "A). This will likely trip the breaker and poses a fire risk.";
warningElem.style.backgroundColor = "#fdeaea";
warningElem.style.color = "#c0392b";
warningElem.style.border = "1px solid #c0392b";
} else if (totalAmps > safetyLimit) {
warningElem.innerHTML = "⚠️ CAUTION: High Load. You are using " + totalAmps.toFixed(2) + "A. While below the " + breaker + "A limit, it exceeds the 80% safety margin (" + safetyLimit.toFixed(1) + "A) for continuous use.";
warningElem.style.backgroundColor = "#fff4e5";
warningElem.style.color = "#d35400";
warningElem.style.border = "1px solid #d35400";
} else {
warningElem.innerHTML = "✅ SAFE: Load is within safety margins. The total draw of " + totalAmps.toFixed(2) + "A is well handled by the " + breaker + "A circuit.";
warningElem.style.backgroundColor = "#eafaf1";
warningElem.style.color = "#27ae60";
warningElem.style.border = "1px solid #27ae60";
}
}