An electric shock from a neutral wire can be caused by a broken, loose or disconnected neutral.
It can also be caused by incorrect wire identification (the wire is actually live with neutral insulation color coding).
A shock from the neutral could also occur if the main earthing system has been disconnected. This post will try to explain what an electric shock is and how someone could get a shock from a neutral from an electrician’s perspective.
What Is An Electric Shock?
An electric shock is a sensation that occurs when someone makes contact between an electrically live surface and earth. This results in current flowing through the body and along the skin to earth. An electric shock has the potential to be extremely dangerous so protective breakers like residual current devices (RCDs) exist to protect people from electrocution.
With this being said, an RCD won’t protect you from a shock originating from a neutral wire as I will explain below.
Can You Touch The Neutral Wire?
Normally, the neutral wire should be 0 volts to earth. This means that, in theory, you can touch it without getting a shock.
This is because the neutral wire is connected to the earthing system in the main switchboard via the MEN link.
This MEN link ensures that the neutral wire stays at the same earth potential as earth (0 volts).
This means that you should never get a shock from the neutral unless it has been disconnected from the earthing system somewhere.
With this being said, let’s look into why someone might get a shock from a neutral wire starting from the main switchboard.
Electric Shock From A Neutral Wire? – Reason #1
MEN Link Disconnected At Main Switchboard
Likelihood: Low unless someone forgot to reconnect the MEN link after doing testing.
When an electrician is doing electrical testing at the switchboard, the MEN link can sometimes be disconnected under some circumstances (such as doing an insulation resistance test on a circuit).
If the MEN link is not reconnected then voltages can appear on neutrals throughout the home. Touching a neutral in this case would cause an electric shock to occur.
Electric Shock From A Neutral Wire? – Reason #2
Broken, Loose Or Disconnected Neutral At Switch
Likelihood: Low – neutral wires can break with smaller cable sizes (lighting cable typically).
A broken, loose or disconnected neutral at the switch can cause voltage to appear on the neutral of the light fitting or appliance. This is because the neutral has been disconnected from the earthing system. A broken neutral in lighting is relatively common with smaller cable.
Electric Shock From A Neutral Wire? – Reason #3
Neutral Wire Is Actually Phase
Likelihood: High – somewhat common in 2 way switching.
The neutral wire has been used as a phase wire by a dodgy homeowner or electrician. If this has happened then the wire will actually be 230 volts (phase wire voltage) instead of 0 volts (neutral wire voltage). Touching this will definitely give a shock and probably trip an RCD too.
This is why testing of wires should always be done before touching them.
Electric Shock From A Neutral Wire? – Reason #4
Earth Wire Disconnected At Earth Pin
Likelihood: Low
Usually the earth pin is located just outside the house. If the main earth has been disconnected from the pin then any neutral will not be connected to earth. This means that voltages can appear on the neutral which can give someone an electric shock. This sometimes occurs due to line trimmers cutting the cable connection to the pin or something similar.
Electricians Perspective
The most likely cause of shock from a ‘neutral’ in our experience has been a false labelling of a phase wire.
Normally, a phase wire must be correctly color coded to prevent misidentification. With this being said, you should always test a circuit to not contain voltage before touching any wires. A broken, loose or disconnected neutral is a dangerous situation. This could happen at the main neutral in the switchboard, the MEN link at the switchboard or any neutral at a switch or wall socket.
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