19 Jun 2026
Have you ever noticed your lights briefly dim when the air conditioner starts running? This is a fairly common occurrence in homes, apartments, and commercial buildings, especially when the AC is first switched on.
In most cases, this is completely normal. However, if it happens frequently or becomes more noticeable over time, it may be a sign that your electrical installation should be inspected.
Why Do the Lights Dim?
When an air conditioner is first turned on, its compressor requires a much higher electrical current than it does during normal operation. This is known as the starting current or inrush current.
This sudden surge in current can cause the supply voltage to drop momentarily. As a result, lights connected to the same electrical circuit may briefly appear dim before returning to their normal brightness.
Is It Normal?
It is generally considered normal if:
- The lights dim only briefly when the AC starts.
- The lights return to normal brightness almost immediately.
It should be checked if:
- The lights flicker or dim frequently.
- The dimming lasts for an extended period.
- The circuit breaker (MCB) trips repeatedly.
- Power outlets or switches feel warm or hot.
- The AC does not seem to perform as efficiently as usual.
If you notice any of these signs, it is a good idea to have your electrical installation inspected so the cause can be identified early.
What Causes It?
Besides the AC's starting current, several other factors can make lights more likely to dim.
1. The Cable Size Is Not Suitable
If the electrical cable is too small for the connected load, it will experience a greater voltage drop. When the AC draws a high current, the effect becomes more noticeable through the lighting.
2. Poor Cable Connections
Loose or corroded cable connections increase electrical resistance, making the power supply less stable.
3. Too Many High-Power Appliances on the Same Circuit
If the AC, water pump, electric oven, or other high-power appliances share the same circuit as the lighting, changes in electrical load can more easily affect the brightness of the lights.
4. The Electrical Installation No Longer Matches Current Needs
As more electrical appliances are added over time, the original electrical installation may no longer have sufficient capacity. This can make voltage drops occur more frequently.
How Can You Prevent the Lights from Dimming?
A few simple steps can help keep your electrical supply more stable.
- Use electrical cables that are correctly sized for the required load.
- Make sure every cable connection is secure and properly installed.
- If possible, provide a dedicated circuit for high-power appliances such as air conditioners.
- Use electrical installation components that comply with applicable standards.
- Have the electrical installation inspected periodically, especially after adding new electrical loads.
The Importance of High-Quality Cables
In addition to having an adequate power supply, the quality of the power cable also plays an important role in maintaining a stable electrical installation.
A high-quality cable with a reliable conductor and durable cable insulation helps deliver electricity more consistently while minimizing voltage drop. That is why residential cables, household cables, building cables, commercial building cables, and industrial cables should always be selected according to their intended application and the relevant standards.
Choosing products from an experienced Indonesian cable manufacturer also helps create a safer, more reliable, and longer-lasting electrical system, whether for residential use or large-scale national infrastructure cable projects.
Conclusion
Lights that briefly dim when an air conditioner starts are generally considered normal. This happens because the AC compressor requires a higher starting current when it first begins operating.
However, if the lights flicker frequently, remain dim for an extended period, or are accompanied by other signs such as a tripping circuit breaker or warm power outlets, the electrical installation should be inspected.
With a properly designed electrical installation and the use of quality power cables, low-voltage cables, and safe electrical cables, electricity can be distributed more efficiently and reliably, allowing electrical equipment to operate at its best.
