Induced Voltage In Domestic Wiring
Posted: Thu Oct 05, 2023 5:04 am
I was doing some testing on my switchboard at home, and I’m trying to understand what is going on here..
When I put my volt meter across the line and load side of the MCB supplying the range circuit (range switched on), there is 0V when MCB is ‘on’ and 230V when ‘off’. This all makes sense, however when I switch the range off so it’s an open circuit, and test across the MCB (still in the ‘off’ position) there is about 200V.
For another test; I got a 50m roll of 2core TPS, put one end on the ground, with both cores isolated from each other and floating in air. With the other end of the cable I connected one core to the neutral bar, and the other core is just floating in air, with the insulation stripped back for testing. When I test between this core I’ve stripped back and the live terminal of the main switch, I’m getting roughly 200V, even though same as the first test with the range it’s an open circuit?
When I disconnect the core I connected to the neutral bar with the 50m roll of TPS, so it’s completely isolated, and repeat the same test as above, I’m getting about 20V. It’s a lot less, but I don’t understand why it’s not 0V.
This is all a bit of a mystery to me, I think it may have something to do with induced voltages? Is someone able to explain how these test results may occur?
Thanks!
When I put my volt meter across the line and load side of the MCB supplying the range circuit (range switched on), there is 0V when MCB is ‘on’ and 230V when ‘off’. This all makes sense, however when I switch the range off so it’s an open circuit, and test across the MCB (still in the ‘off’ position) there is about 200V.
For another test; I got a 50m roll of 2core TPS, put one end on the ground, with both cores isolated from each other and floating in air. With the other end of the cable I connected one core to the neutral bar, and the other core is just floating in air, with the insulation stripped back for testing. When I test between this core I’ve stripped back and the live terminal of the main switch, I’m getting roughly 200V, even though same as the first test with the range it’s an open circuit?
When I disconnect the core I connected to the neutral bar with the 50m roll of TPS, so it’s completely isolated, and repeat the same test as above, I’m getting about 20V. It’s a lot less, but I don’t understand why it’s not 0V.
This is all a bit of a mystery to me, I think it may have something to do with induced voltages? Is someone able to explain how these test results may occur?
Thanks!