Earthing Rod length

Probably an easy one for you guys, I’ve had the first part of an electrical installation done now, which will eventually become a Tesla charging point, I’m pretty sure, when the actual charger goes in, an earthing rod will be required (although not mentioned in the fitting instructions) but how long is a typical earthing rod, are they really 8’-0” ?

thanks

paul

usually 4ft. how many you need is another question though... around here you can easily get <100 on a single rod thats not even fully in. other parts of the country and different ground conditions you may need multiple extendable rods to get a stable reading

If you think 8ft is impractical then I would look at an earth nest, multiple shorter rods interconnected. But look in to the method used for a nest.

I’ve known of rods going 60 to 100ft down in boreholes filled with Bentonite.

Tony S said:

If you think 8ft is impractical then I would look at an earth nest, multiple shorter rods interconnected. But look in to the method used for a nest.

I’ve known of rods going 60 to 100ft down in boreholes filled with Bentonite.

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I doubt for a car charger though!?

Sharpend said:

I doubt for a car charger though!?

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No, a 33/11kV substation in Nottingham's Victoria Centre.

To get a low earth reading you do what is needed

Totally agree. 

They sem to like rods for car chargers, but the actual requiremenst depend on the earthing system and other local potential earth paths. I was talking to afrined of mine this morning who has just done an EV course, couldnt help but laugh at things like class 1 external light fitting within 8m may need to be changed to Class II (seriously). I'm trying to think of the last time I decided to touch my car and touch an external light at the same time....  :^O

binky said:

They sem to like rods for car chargers, but the actual requiremenst depend on the earthing system and other local potential earth paths. I was talking to afrined of mine this morning who has just done an EV course, couldnt help but laugh at things like class 1 external light fitting within 8m may need to be changed to Class II (seriously). I'm trying to think of the last time I decided to touch my car and touch an external light at the same time....  :^O

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dont need to touch the external light at the same time. simply touching the car alone, if there is a fault and the earth voltage higher, could give you a shock

but the street light next to it will probably an TNCS and will have the same issue, but thats fine

your missing the point, due to TTing charge point if the house is on a diffrent earth system the outside light could be at a different earth potential.

and don't forget outside taps plumbed in copper, although that scenario is more likely ie washing car whilst it's being charged.

Charger indside garage with car inside is also different to car outside garage with charge point outside, so you can't have charger inside and plug car into if parked outside without risk assessing earthing arrangements.