So THAT’s the difference between two and three-pronged plugs!

Have you ever been plugging in an appliance and wondered why some have two prongs and some have three? Well,

Have you ever been plugging in an appliance and wondered why some have two prongs and some have three?

Well, there’s a good reason. You may have heard the third prong actually helps safety, but if this is so, why are toasters and similar appliances often without a ground prong, when low-voltage devices (like Apple laptop cords) often do have them?

If there is no ground prong, charge builds up on the metal chassis. When you touch your appliance, it can suddenly bite you. This is called electrical discharge and it goes from the appliance, through you, and into the ground.
In extreme cases, some electrical parts inside the appliance might come into contact with the external chassis. This is even more dangerous, because this could happen to household-voltage appliances (110V or 220V)
Now, why do some appliances have a ground prong, and some don’t? To find out the answer, have a look at the electrical labels of your appliance. Do you see different symbols, such as the “CE” mark? These are are safety certifications that allow your appliance to be sold in particular countries.

IEC Protection Class I
Appliances with this symbol require a ground prong.


IEC Protection Class II

Appliances with this symbol do not require a ground prong, because they are “double-insulated”, meaning the plastic has an extra coating to avoid electric shock.

In Australia, New Zealand, Fiji and Papua New Guinea, the flat pins in a V-shape plus the vertical pin represent Active (left pin), Neutral (right pin) and Earth (vertical pin).There are unearthed versions of the plug used with this outlet that have the two flat inverted V-aligned pins, without the Earthing pin. To sum it up, these plugs are only to be used for devices where other safety standards are in use (e.g. double insulation).

So if you buy a cheap cord or plug, make sure it has either three prongs or don’t buy it at all – it mightn’t be made to the same standards as those with three prongs.

Share your thoughts below.

  1. Angie B  

    You learn something new every day!

    • Kevin  

      Actually a bit different to DC, its active and Neutral and many older (pre-fifties) homes have wall sockets wired the wrong way around, as there was no rule at that time – can be very dangerous.

  2. Some appliances need the earthing pin, others (double insulated) do not. NEVER buy a power board or extension cord with only a two pin plug.

  3. Consider having a safety cut out device fitted to you house preferably at the source. This doesn’t act as an earth but detects residual current and terminates the power in the event of an imbalance thus preventing shock. Not to be confused with circuit breakers. Ask you local electrician to give you a quote, not a big job to install but may save your life. 30 ms (milliseconds) is the cut off time that the RCD should engage.

    • In Victoria at least all new electricity installations or upgrades require a safety switch on the main board. If you don’t have one then do get one. A real life saver.

    • I’m not sure about that but do know that in certain states rental properties must have one. It’s worth checking out with the local area authority in your state though. Better safe than shocked

    • On another note. I once purchased (in bulk for work) a quantity of heavy duty 240v extension leads. As was our QA practice at the time I had each lead (all 500 of them) checked. The plug and socket ends were moulded so we had to check with a voltage checker ( a battery operated relatively cheap instrument) We found every lead faulty. The active from the plug connected to the neutral of the socket and vice versa. This could have resulted in injury or worse under certain circumstances. When buying anything electrical do not assume it is 100% safe. What a shocker.

    • John Steven – Even more fun when the electrician wires your wall socket the wrong way round. Yes it does happen!

    • Yep, happened in my house in FNQ. I only found it when my circuit beeper went off on the desk next to a lead that was switched off at the wall. You can buy these testers at Bunnings for about $20 no need to expose any connections, looks like a pen with a flat plastic end, lights up flashes and beeps where a live circuit is found

    • I think ELCBs are mandatory nowadays with new and reworked installations. Everything’s a whole lot safer than with the SWER supply I grew up with as a child (some of which are still the go in isolated areas of this huge continent, albeit modern technology makes its use a whole lot better than once was the case.

    • My home was built in 1993, it has a safety switch installed, I think it was law in QLD by that time that all new homes had to have them.

    • Victoria Alexandra D’Arienzo what do you expect from a bunch of bright sparks 🙂

  4. These power boards should never be used no on and off switches for each power inlet how do you teach children safety on electricity also imbalance in power supply seen a friends house caught fire due to these type of boards safety first with electricity needs to be reinforced

    • Unfortunately a lot of people are either dumb or careless when it comes to electrical safety – even some over sixties 🙂

    • Robert Hind no can’t believe that we have been searching all our lives for the meaning of life we have wisdom in great magnitudes except when we do dumb things lol

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