A circuit breaker will trip when water enters an electrical enclosure and creates a short circuit across live components.
This is a common occurrence with outdoor lighting, outdoor power sockets and outdoor appliances which are exposed to the weather when it rains.
This post will talk about why a circuit breaker would trip when it rains and three things that could be causing it – from an electrician’s perspective.
Why Rain Causes Breakers To Trip
Rainwater conducts electricity. This allows electrical current to flow freely. This is the opposite of an insulator which doesn’t allow current to flow.
Touching a wet surface which is in contact with live electrical parts, such as a live terminal or wire, allows electricity to travel through the water onto one’s skin causing a shock.
Getting a mains shock poses a big safety concern. As a result, circuit breakers, particularly RCDs exist.
They work by automatically shutting off the power to the circuit when a situation like this occurs. It’s also why conductive components need to be connected to earth.
Water can also create a short circuit which also will trip a breaker, especially MCBs. This occurs because current travels across the water from phase to neutral.
A short circuit can be quite explosive and a big fire hazard. As a result, MCBs are designed to shut off power automatically when they occur.
Rain has the potential to cause both of these faults tripping either a RCD or MCB. Let’s look at how rain can get into live electrical parts in the first place.
Why Does My Circuit Breaker Trip When It Rains? – Reason #1
Check Outdoor Lighting
Is outdoor lighting present? Outdoor lighting has the potential to get water intrusion during rain.
All types of lights are susceptible whether they are mounted on the wall or the soffit.
Outdoor lights are supposed to be protected against the weather. Outdoor lights should have:
- A high IP rating which makes them suitable for being exposed to water.
- Installed and waterproofed appropriately such as having a flashing or using silicone to seal off any water intrusion.
Over time light fittings can deteriorate resulting in its waterproofing becoming less effective. Water getting inside the light fitting or light bulb, especially if the rain storm is particularly strong will trip a breaker.
Why Does My Circuit Breaker Trip When It Rains? – Reason #2
Check Outdoor Power Point
An outdoor power socket can trip a breaker when it rains.
Outdoor power sockets cannot be of the same type as the ones used indoors. Outdoor power sockets need to be properly IP rated ensuring that they are able to handle exposure to moisture.
Standard indoor power sockets will immediately allow water inside causing a breaker to trip.
An outdoor power socket could also have been installed in a way which affects its inherent waterproofing.
This includes the cable going into the top of the power socket (causing water to fall in between gaps).
Not adequately sealing cable entries or screw holes will also result in water seeping inside during rain storms.
Why Does My Circuit Breaker Trip When It Rains? – Reason #3
Check Outdoor Electrical Appliance
Any outdoor electric appliance (or extension lead left outside) such as a water pump or spa pool can be susceptible to water intrusion onto electrical parts.
This will result in a breaker tripping. Unplugging any outdoor appliances and resetting the circuit breaker could identify any appliances at fault. If the breaker keeps tripping then an outdoor appliance isn’t at fault.
Electricians Perspective
Outdoor lighting is a common reason why circuit breakers trip when it rains in my opinion. With this being said, any electrical components found outdoors such as power sockets, appliances or extension leads will trip a breaker if exposed to water.
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