Continue to Site

Welcome to

Welcome to our site! is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

AC outlet shock while ungrounded... why?

Not open for further replies.


Newbie level 4
Nov 25, 2012
Reaction score
Trophy points
Activity points
I recently got shocked when I touched a live lightbulb socket with a butter knife. However, I was standing on a wooden chair when I did so. How did I complete the circuit standing on a wooden chair? I have been reading a lot in order to understand the specifics involved in electric shocks but I still don't understand why I got shocked if I wasn't grounded. The shock was pretty intense. I involuntarily threw the knife across the room at 100mph.

was it a complete wooden chair?

I think wooden chair acted as dielectric between you and the ground.

Hello ratob,

normally wood is good isolator, but if it is wet, it is only a resistor. More water inside the wood will give less resistance. If you don't use rubber shoes you close the electric circuit from Line through your body and the chair to ground. So the line voltage will bite you. :oops:

It is better to use dry rubber gloves.



I was in the middle of the room, did not touch any walls. I might have had a foot on the nearby table, but it too is a big block of solid wood.

Don't have a moisture meter to check the wood but don't have any reason to believe it is high.

Is it possible that I touched both the hot and neutral wiring in the light socket with the knife? It is a very old socket, at least 30 years old.

I don't remember what I was trying to do with the butter knife. I got distracted and didn't realize the stupidity of what I was doing until I got zapped.

Hello ratob,

Is it possible that I touched both the hot and neutral wiring in the light socket with the knife?

I think, you don't touch both wires with your knife, but with one hand you touch a metal part of the socket that was grounded.

That will explain why you throw your knife through the room.



You may have seen simple voltage testers, sometimes incorporated into screwdrivers, sometimes not.

They have two connectiions.

In the case of a mains testing screwdriver, the connections are the screwdriver's tip and a small metal contact at the other end.

To use it, you put a finger or thumb on the metal contact and touch the wire, or whatever you are testing, with the screwdriver's tip. If there is voltage on it (with respect to Earth) the neon inside will strike and light up.

In the case of a separate tester, they have two wires, around 3" long, with a small metal probe at the end of each of them.

To use it, you place one probe on one wire, for instance, and the other probe on the other wire. That will tell you if there is vboltage between the two wires by the neon lighting.

Or, you can hold one of the probes and with the other probe touch a wire or connector to check if there is voltage on it (between it and Earth).

They work on the priciple that, although you may not realise it, there is an albeit high, a very high, resistance path from you to the Earth.

The small current which flows from the live mains point through the neon and its series resistance, and your body to the Earth is sufficient for the neon to strike.

If you are not convinced, buy one of those testers and make some checks yourself. You may think you are completely isolated from the Earth, but seldom is this true.

Not open for further replies.

Part and Inventory Search

Welcome to