Why does my charger get so hot?

You, me and pretty much everybody else around the world, spend time during the day connecting phones or other electronic devices to power to ensure they don't run out of battery. It's common practice and something none of us really think about. But do you know what you're actually plugging in? Or why some devices produce heat and others don't? Why a fire could start from simply plugging in a device like a baby monitor, a phone or just a regular plug?

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With a 35% increase in electrical fires in the home between 2014 and 2015, it's important that people know a bit more about whats going on once power is connected to a device. Having worked as an electrician for years, I saw many of the issues that can arise and the most common causes were:

1) Faulty devices e.g damaged or malfunctioning components.

2) People using devices in environmental conditions which are not suitable e.g chargers on beds.

3) Incorrect charger for device e.g charging your portable speaker with a phone charger.

4) Uncertified devices, typically bought at discount stores or online.

5) Unqualified person tampering with a device e.g changing a plugtop and not tightening the wires correctly.

The first thing to keep in mind is that an 'electrical device' and an 'electronic device' are different. Electrical devices typically take AC (Alternating Current) electricity. Examples of this would be your kettle, iron, toaster or blow-heater.




An electronic device takes DC (Direct Current) electricity and examples of this would be your phone, tablet or laptop. When you plug your electronic device into a power outlet there is a lot going on behind the scenes that you probably don't know about.

Have you ever wondered what the block in the middle of your laptop charger is for? Well, the power in homes is AC electricity, so a transformer is needed to convert that power to DC for your phones, laptops etc. That block is the transformer, and if you touch it, it is typically hot while plugged in, and this is completely normal, as a by-product of going from AC electricity to DC electricity, is heat. Phones are the same but they require a smaller transformer which is contained within the plug top, as they don't need as much power as laptops.

Issues arise when people are dragging chargers around with them from place to place and they are continuously being knocked off things and thrown around. You may not be able to see it but within chargers, there are a lot of components and if one of them become damaged it can lead to the device overheating and causing a fire. 

burnt charger, firemole, technology

No matter what brand you buy, all devices will have a failure rate and accidents do happen. Big corporations put rigorous testing procedures in place, but if you look at any big brands website, you will find a list of active recalls ongoing due to their products posing a fire hazard. I don't think we need to try too hard to think of a couple of big names who have had trouble over the last couple of years. 

With anything that produces heat, it's important that there is good airflow so the heat can escape. This isn't the case when people use electronic devices on beds or other soft surfaces. The cushioning traps the heat and the phones, chargers or whatever it may be, will continue to heat up and there have been many incidents of fires caused by this and also people, particularly younger children, burning themselves. These are the exact type of incidents Firemole can prevent.

One of the leading causes of electronic fires is people not using the correct charger. A portable speaker will draw a lot more power than a phone, so their chargers are designed to allow for more current to flow. If you use a charger from a smaller device, that doesn't need as much power, the portable speaker will be trying to draw more current than the charger is designed for and this can lead to overheating and therefore a fire.

Buying genuine chargers is expensive but worthwhile. Nine out of ten "Apple" chargers on Amazon were found to be counterfeit and unless you really know what you are looking at on the charger, you can be easily duped. When I am doing presentations and talking with investors I bring in a genuine and a fake Apple charger. I'm yet to find anybody who can pick the fake and explain why (sometimes they are just lucky and pick the right one). The fake one I bring in weighs 20grams less than the genuine one which means there are a ton of components missing on the inside. Typically the components that are missing are the ones that shut the power off once your device is fully charged. Even though the comments on Amazon about these chargers specifically say "DO NOT BUY THIS IT GOES ON FIRE" people are still buying them. You may say you would never buy one, but do you know what ones your kids are buying? Even the ones you can buy in your local shops may be fake. There are numerous cases of shop owners being prosecuted for selling uncertified chargers and there are many cases of these chargers causing fires. 

During my time as an electrician, I went to a number of houses where there were small fires caused by electrical devices (AC electricity). Generally, these incidents were caused by things that draw a lot of electrical current, like blow heaters, and the homeowner says "I have absolutely no idea why this happened". These fires were not actually caused by the heating element in the heater, but the plug top. The first question I ask is "did anybody change the plugtop?". Sometimes they will say 'Yes' but the majority would say 'No'. It doesn't take long to figure out that somebody has been at it when there is a nail replacing the fuse or frayed cables sticking out everywhere within the plugtop. On the second time asking "Are you sure nobody has been at this" they tend to fess up. "Oh ya I forgot, I had no fuse so I looked on Google and it said to use a nail". Don't always take Google's advice as you never know who is writing the content.

There is an electrical saying "Loose wires cause fires" and this is very true. If you do not tighten wires properly they can produce heat, especially in larger appliances that draw a lot of power. This was typically the case with fires that started at plug tops. People would leave wires, or parts of the wire loose and this can lead to heat being generated and a fire starting. 

overloaded socket, fire, firemole

The other common issue I came across was people in kitchens using multi-socket adapters and having fridges, dishwashers and washing machines plugged into the one adapter. This overloads the socket that is plugged into the wall and can cause a fire.

Many electrical fires start out slow and smouldering. Firemole is designed to warn people of high temperatures to try and catch the fire before it breaks out and spreads. Firemole attaches to any flat surface and it sounds an inbuilt alarm if temperatures over 54C or 129F are detected.

As our reliance on electrical and electronics devices becomes more and more prevalent every year, it is important that you know how to use these devices appropriately so your home doesn't fall into the growing statistic of house fires.