An electric shock from a gas pipe can be caused by static electricity, a live wire making contact with the gas pipe, or a transposed wire.
This post aims to provide information to help you understand why this might be happening and what you can do about it.
What Is An Electric Shock?
An electric shock is an unpleasant sensation that occurs when contact is made between a surface or wire with high electrical potential (voltage) and the ground.
When this happens, a circuit is created allowing electrical current to flow between the point of high voltage and earth.
An electric shock is unpleasant and very dangerous because current travels through the body and through organs such as the heart, potentially damaging them in the process.
The damage from an electric shock depends on how strong the electrical current is and how long someone is exposed to this current.
Obviously, the longer that someone is exposed to a shock, the more likely it is to cause long term harm. The same can be said if the shock has more current.
The level of current that flows through someones body during a shock depends on how well someone is connected to earth.
Someone standing barefoot on a damp ground will have a better connection to earth than someone wearing insulated shoes.
In the event of an electric shock, this person standing barefoot would have much more current travel through them than someone wearing shoes.
Because electric shocks have the potential to cause severe harm, there are protection measures in place to ensure that power is shut off if an electrical fault occurs which could give someone an electric shock.
RCDs
In modern homes, residual current devices (RCDs) are used to automatically cut off power to a circuit if electricity is leaking to earth (electric shock).
An RCD can detect if an electric shock is occurring and shuts off power once a certain threshold is met.
This threshold is 30 milliamps of current within 300 milliseconds in the standard domestic situation.
These figures were determined from the Shock Limits graph which shows how the body responds to different levels of current over varying amounts of time.
An RCD is designed to trip within enough time to prevent serious harm to people.
Domestic circuits including all power points and lights must be protected by an RCD.
Earth Bonding
Another electric shock protection measure is earth bonding.
As gas pipes are typically made of copper which is a conductive metal, they must be bonded to earth.
Usually the gas pipe will have a wire clamped to it. This wire will trace back to the earth bar in the switchboard.
Earth bonding the gas pipe prevents voltages from developing on the gas pipe. Bonding also helps ensure that RCDs will operate effectively.
Gas Pipe Fault Finding
As mentioned above, if the gas pipe is made of copper or another metal, it will be bonded to the earthing system.
This means that a wire with green insulation will be clamped to the gas pipe somewhere.
The earth bar is located at the switchboard.
Gas hot water is typically plugged into a powerpoint socket, so it should also be protected by RCD.
Electric Shock From Gas Pipe – Reason #1
Static Charge
Likelihood: High – especially if clothing is polyester or atmospheric humidity is low.
The first potential cause of electric shock is static electricity. This occurs when charged electrons build up on the surface of clothes and hair, especially when humidity is low.
You may not realise that you have a static charge until you touch something like a door handle (or another appliance) and receive an electric shock.
As a gas pipe is bonded to earth, it’s possible to get a shock via static electricity when you touch it.
Electric Shock From Gas Pipe – Reason #2
Wire Touching Gas Pipe
Likelihood: Moderate – high if the switchboard has no RCD’s, or the gas pipe is not bonded to earth correctly.
Gas pipes must legally be kept a certain distance away from wiring for obvious reasons.
However, sometimes that doesn’t happen. A wire or appliance with a fault could be touching a gas pipe, either directly or indirectly.
A common culprit in our experience is rodent chewed wires. These chewed wires can expose live copper which could cause electricity to flow on the gas pipe.
Loose and broken wires are also possible reasons for why a wire might be touching a gas pipe.
The loose or broken wire might be inside the water heater or wall socket itself.
Electric Shock From Gas Pipe – Reason #3
Transposed Wires
Likelihood: Low – unless someone has been doing electrical work recently.
This is a very dangerous situation where someone has done electrical work and connected wires incorrectly.
Swapping phase and neutral leads to energising all earthed components, which would give someone an electric shock.
As mentioned earlier, gas pipes are connected to the earthing system. If someone has been doing electrical work recently (such as the homeowner) it is important to ensure that the work has been done to the right standard.
Electrician Perspective
The most likely reason why someone will get a shock from a gas pipe in most scenarios is static electricity.
However it is important to check whether your switchboard has RCD’s and whether the gas pipe has a bonding wire clamped to it (it will be a green wire). If one of these two things is missing, then it is possible that an electrical fault such as a damaged or broken wire is making contact with the gas pipe.
We Fix Faults is all about diagnosing electrical faults, if you want us to cover a topic or provide more information then don’t hesitate to send us a message above.