Why do I get a small shock off my taps or appliances?

People describe this as a tingle, a buzz, or a shock "only when I am barefoot on the kitchen floor", and treat it as an oddity of the house. It is not. Metalwork you can touch is earthed precisely so that it can never be at a different potential from you, and if you can feel a difference, something in that protective system has failed.

Safety

Step by step

1. Stop and note the exact conditions.Which metalwork, whether you were wet or barefoot, whether a particular appliance was running, and whether it happens always or only sometimes. This information genuinely shortens the electrician's visit.
2. Identify whether one appliance is involved.If the tingle comes from a washing machine, cooker, kettle or shower casing, or only when one appliance is running, unplug or isolate that appliance. A faulty appliance putting voltage on its case is the most common single cause and the easiest to remove.
3. Isolate rather than investigate.If you can identify the circuit involved, switch it off at the consumer unit. Do not open accessories, do not test with your hand, and do not use a non-contact pen and draw conclusions from it.
4. Understand why the RCD may not have tripped.An RCD trips at around 30mA of leakage. A fault can put voltage on metalwork with less current than that flowing, particularly if the person feeling it is well insulated. A tingle you can feel with no trip is entirely possible and is not evidence that the installation is fine.
5. Understand the main bonding cause.Main protective bonding conductors connect the incoming gas and water services to the installation's main earth so that everything metallic in the house sits at the same potential. If they are missing, undersized or disconnected — very common in older houses, and sometimes removed during plumbing work — a potential difference can appear between a tap and the floor.
6. Understand the plastic pipe complication.Where copper pipework has been partly replaced with plastic, a metal section can be left electrically isolated from the bonding, so it floats at whatever potential it picks up. This is an increasingly common cause and is not visible without testing.
7. Understand the supply-side cause.On a PME supply, a failing network neutral can raise the potential of the whole earthing system relative to true earth, which is felt most where you contact both earthed metal and real ground. If your lights also flicker or dim, mention that — it points strongly this way and it is a network fault.
8. Get it tested today, not eventually.Ask for main bonding to be verified, earth continuity checked at the affected metalwork, and the appliance tested. If lights are also flickering, call 105 as well — the free network line across Great Britain, or NIE Networks on 03457 643 643 in Northern Ireland — because a supply-side neutral fault is the network's to fix and is urgent.

Tips

• If plumbing work has been done recently, say so. Bonding conductors removed and not replaced is a genuinely common sequence.
• A tingle only when barefoot on a tiled or concrete floor is a classic sign, because that is when you are best connected to true earth.
• Do not test it repeatedly to see if it is still there. Each test is a shock, and shock severity depends on conditions that can change.

Common mistakes

• Deciding it is static — Static is a single sharp snap, usually from carpet and synthetic clothing, and it does not repeat reliably from the same tap. A repeatable tingle from earthed metalwork is not static.
• Getting used to it — The conditions that make it a tingle rather than an electrocution are the conditions of the moment — dry hands, shoes, a small contact area. Wet hands and bare feet change the outcome entirely.
• Assuming the RCD would have tripped if it were serious — An RCD needs 30mA to flow to earth. A dangerous potential difference can exist with much less current flowing, especially through a well-insulated person.

If it doesn't work

Questions people ask