An electric shock from a vacuum cleaner is most likely due to static electricity. A damaged cord or plug could also be a reason. This post will try to explain how a shock could occur and why it’s happening from the perspective of an electrician.
Why Does An Electric Shock Happen?
An electric happens when contact is made between a surface with voltage and earth.
This could be because someone is touching a live wire or conductive surface that has been energized.
When this happens a circuit is created and electrical current travels from the wire to earth. The current travels along the skin and through the body.
This is what creates the ‘electric shock’ sensation. This sensation can be deadly depending on how much current someone is exposed to and for how long.
The better that someone is grounded, the more current that will flow and the stronger the electric shock will be. For example, someone is well grounded if they are touching something that is grounded such as a hot water cylinder.
They are also well grounded if they are standing on a damp ground and not wearing shoes. Both of these situations can lead to a stronger electric shock than if someone was wearing insulated shoes, for example.
As electric shocks pose a great danger to health, residual current devices must be installed for all power points.
This is because the biggest risk for electric shock comes from handheld appliances plugged into power points. A vacuum cleaner is an example of this. The risk increases if a handheld appliance is used in a wet area.
An RCD works by shutting off power to the circuit and appliance (vacuum cleaner) when an electric shock or risk of shock occurs.
An RCD is designed to trip when a certain current and time threshold is met.
For a standard RCD, this is 30 milliamps within 300 milliseconds which should prevent anyone from getting permanent damage from a shock. This threshold is taken from the IEC shock limits graph.
A good earthing system is required for RCDs to work correctly. This means that resistance on the earth wire needs to be low enough and all conductive surfaces are bonded to earth via a bonding cable.
Vacuum Cleaner Fault Finding
A vacuum cleaner could either be a class 1 or class 2 appliance.
Looking at the plug will give you some clues. The plug for a class 1 appliance has three prongs which includes an earth plug pin. This means all conductive parts of the vacuum cleaner are bonded to the home’s earthing system via the wall socket it is plugged into. When a fault occurs with the vacuum cleaner it will trip an RCD or MCB.
If the vacuum cleaner only has two prongs then it is a class 2 appliance. This means that the live parts of the vacuum cleaner are covered with an extra layer of insulation. This protects the user from exposure to electrically live parts.
Checking the switchboard for a tripped circuit breaker is a good idea. If someone received a shock while using the vacuum cleaner, an RCD could have tripped in the switchboard.
Electric Shock From Vacuum Cleaner? – Reason #1
Static Shock
Likelihood: High – in a low humidity environment or specially vacuuming carpet.
Static electricity is a phenomenon that occurs when charged electrical particles build up on clothes, skin and hair. It can occur due to friction between the head of the vacuum cleaner and the carpet, resulting in an electric shock for the user of the vacuum. A static shock is more likely if humidity in the air is low and someone is wearing polyester clothes. Static is a common cause of shock with other appliances such as hair dryers and TVs.
Electric Shock From Vacuum Cleaner? – Reason #2
Broken Insulation On The Vacuum Cleaner Cord
Likelihood: Moderate
The power cord on the vacuum cleaner poses a risk if the insulation has been damaged.
Damage can happen to power cords exposing live strands of wire. These strands can give someone a shock if they were to directly or indirectly touch the strands. To check if this is the cause of the shock, always ensure that the vacuum cleaner is unplugged from the wall socket before inspecting the cord.
Electric Shock From Vacuum Cleaner? – Reason #3
Damaged Plug
Likelihood: Low
A damaged plug could expose wire strands, have faulty prong pins (such as a poor connection to neutral or earth), or a damaged case. Any of these could result in an electric shock.
Electricians Perspective
Vacuum cleaning has a high likelihood of generating static electricity through friction with the carpet. Broken insulation could be the cause of the shock if visible damage or abrasions on the power cord are found.
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