My father wanted to kill a mole by putting a steel pipe into the ground and connecting live wire to it. I thought it would cause the short circuit but it didn’t. Why?
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Dirt and rocks often have very poor conductivity, but this varies a lot with the soil conditions. In your case, the resistance where the metal pipe touches the dirt is just too high for a high for a large amount of current to flow. This also means it is unlikely to electrocute the mole.
Ground rods are copper (steel is an ok conductor not great) and driven 8ft into the ground or if thats not possible laid down so they have 8ft of contact with the soil. How deep was the steel pipe?
Hold up. Did he connect it straight to the mains? Please tell me he had some level of insulation on the bare metal?
To start, I’m a master electrician and instructor…
Alternating current IS NOT “trying to go to earth” per se as an “end goal”. Both AC and DC are trying to return to their source; for DC that’s generally the opposite terminal of a battery from which it left, with AC the source is the windings of either a generator or transformer. Circuits are “circles”, in the most basic AC circuit the hot and neutral are just the “top ending” and “bottom ending” of one of those windings, i.e. they are technically one conductor.
Current does not only take the *path of least resistance*, it will take *all paths available* to source that have a low enough impedance/resistance for current to flow. That means if you had a normal ground rod driven at your house for your electrical service, and drove another a few feet away and connected JUST a hot wire to it, the current would flow through the added rod, through the earth, and back up the original rod on its way back to the transformer winding. If current were “trying to go to earth/ground” as is commonly thought, this would trip a circuit breaker or open a fuse.
Also note, in AC the path of current is a bunch of electrons vibrating back and forth where in DC the electrons move from atom from the source, through the conductor and load, and back to the oppositely charged terminal.
Here’s a page with some illustrations to help it make sense if it doesn’t.
https://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/OpenServiceNeutralCausesDangerousTouchVoltageonMetalParts~20030409.htm
I would imagine it’s because:
A, your father seems to have forgotten to put the neutral wire into the earth with a long steel pipe, thus there was no circuit and there must always be a circuit before current can flow.
And B, IIRC the ground plug isn’t so much to conduct any actual energy down into the earth, but is more so to equalize the installation with the environment to prevent misbehaviour due to strange voltage difference between the powerplant and the house installation.
Meaning that basically the ground doesn’t conduct well enough to zap moles, only enough to get rid of some crooked volts.
Earth can be a good or poor conductor. I’ve seen 7200 volt distribution lines laying on dry sand and not trip the breaker.
An overcurrent device is just that, it needs to see current in excess of its tripping point. In the example above, dry sand is little more than glass, the same thing insulators are made of. It simply didn’t pull enough current to trip.
So maybe your Dad hooked the circuit up to a 20 amp breaker. If he’s in sand, rock, etc., he might only pull 1 amp, or 15 amps…neither of which would trip the breaker. But it only takes 5 milliamps through the body to kill.
What your Dad has done is made a death trap for anything and anyone that touches that pipe, which at the very least opens him up for all sorts of liabilities even if he doesn’t kill someone.
There’s an old story of some idiot that wired his trashcan the same way to keep the neighbors dog from pissing on it. Trouble is, the neighbor kid leaned his bike against it and it killed the kid instead.
Your Dad is playing with fire.
First let me clarify why we call it earthing.
For electricity to flow we have to connect the + and – poles of a battery or any other voltage source and complete a circuit.
We can use wires or anything that is conductive like water or dirt.
With dirt we can stick two poles into the ground and connect one to the plus pole of a battery and connect the other to the minus pole and electricity will flow through the dirt.
With the AC system we have a Generator that is equivalent to the Battery in the the DC System with a Hot Wire as + Pole and Neutral Wire as – pole.
The AC electricity System usually connects the neutral wire at various points to a pole in the ground to earth it and make it possible for electricity to flow from the hotwire through the ground, back to the neutral wire.
This is done for multiple reasons, mainly safety.
The circuit with the pipe in the ground would be the following:
Generator Plus – Hot Wire – the pipe in the dirt – dirt – grounding rod at the house (Transformer Substation) – Neutral Wire – Generator Minus.
Now to your question. Reasons i could come up with why there was no short circuit:
1: Your dad simply connected the Neutral Wire not the “Hot” Wire to the pipe and therefore there was no circuit for electricity to flow.
2: The connection of the pipe to the ground was not good enough. That would mean that some electicity was flowing but not enough for anything to happen.
3:If you take out the grounding rod at the house (Transformer Substation)
You live in an area that uses an “IT” AC grounding system. In this system the Neutral Wire is not connected to Ground or “Earth” at any point in the System completely isolating it from the dirt.
This would mean that there is no circuit closed that the electricity could flow through when you connect the hot wire to the dirt.
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