Recently installed some lights that are sunk in the ground. They had connections for the earthing / ground cable, which I did connect and test to be sure. But I would like to understand why this is required in the first place given that the lamps are literally in the earth. Thanks.
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Because if you relied solely on the contact it makes with the surrounding soil you would be at risk of being zapped after a rainfall, for example.
Because if you relied solely on the contact it makes with the surrounding soil you would be at risk of being zapped after a rainfall, for example.
For a safety earth connection to actually give proper safety, you need a really good connection to earth. This can be difficult, and requires a deep, long buried metal rod (or multiple rods), because the earth itself isn’t a particularly good electrical conductor. In many places, the power company install dozens of earth rods all over their power grid, and connect them together with wires, and then you just connect your house to their earth wire, instead of installing your own rod. This is much more reliable than having your own rod.
A lamp post just buried in the ground near the surface, has an unknown quality connection. So you can’t trust it as a safety feature. You could potentially test it, but soil moisture affects the surface soil, so this will change with weather. If you need safety you can trust, it is usually preferable to connect any metal in the lamp post to a known reliable earth wire.
For a safety earth connection to actually give proper safety, you need a really good connection to earth. This can be difficult, and requires a deep, long buried metal rod (or multiple rods), because the earth itself isn’t a particularly good electrical conductor. In many places, the power company install dozens of earth rods all over their power grid, and connect them together with wires, and then you just connect your house to their earth wire, instead of installing your own rod. This is much more reliable than having your own rod.
A lamp post just buried in the ground near the surface, has an unknown quality connection. So you can’t trust it as a safety feature. You could potentially test it, but soil moisture affects the surface soil, so this will change with weather. If you need safety you can trust, it is usually preferable to connect any metal in the lamp post to a known reliable earth wire.
For a safety earth connection to actually give proper safety, you need a really good connection to earth. This can be difficult, and requires a deep, long buried metal rod (or multiple rods), because the earth itself isn’t a particularly good electrical conductor. In many places, the power company install dozens of earth rods all over their power grid, and connect them together with wires, and then you just connect your house to their earth wire, instead of installing your own rod. This is much more reliable than having your own rod.
A lamp post just buried in the ground near the surface, has an unknown quality connection. So you can’t trust it as a safety feature. You could potentially test it, but soil moisture affects the surface soil, so this will change with weather. If you need safety you can trust, it is usually preferable to connect any metal in the lamp post to a known reliable earth wire.
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