Greenhouse electrics

[SUNRAY]

Using the core of the cable does not necessarily mean that the Armour and gland is also earthed

especially if something like this has been done at the supply end:

https://www.diynot.com/diy/threads/why-i-hate-domestics-yet-again.546386/

 

[bernardgreen]

Is that sufficient with no requirement for further earthing?

The "Earth" in the house is most likely NOT Ground but instead is derived from the Neutral The Neutral is connected to Ground rods at the sub station so in ideal circumstances provides a good "Earth" for houses. But in practise the potential on the Neutral entering the house will be a few volts different from Ground potential at the house. When there is a fault in the supply network the potential on the Neutral can be many volts above Ground and touching the "Earth" in the house ( any Earthed metal item and something in or on the Ground outside the house presents a risk of electric shock.

This is why metal pipes coming into the house from the Ground are bonded to the Earth in the house. The pipe and all Earthed metal items are kept at the same voltage by the bond connection.

A metal greenhouse frame on the Ground may be at a different voltage to the voltage on metal items in the greenhouse that are "Earthed" using the "Earth" from the house if the frame of the greenhouse is not bonded to the "Earth" imported from the house into the greenhouse.

 

[LeadFarmer]

Thanks for everyones advice. Finished installing it all today

Used a 20S CW gland to connect the SWA cable to the outdoor socket. Cutting the SWA cable to neatly expose sone of the steal braiding so the nut can still thread on was a bit of a pain. Whilst I understand earthing at the socket end of the cable shouldn't be needed, I did so anyway. Mounted the socket to a timber board which I attached to the greenhouse frame using cropped bolts that slide into the frame channel.

Decided to have the cable entering the socket from underneath, though I appreciate a side entry may be better but that opens up the debate of whether to drill a drain hole into the socket to release any water, rendering the IP protection a bit useless...

 

[333rocky333]

I tend to wonder if you need some sort of cable restraint, after all your only glanded into a plastic box.

 

[winston1]

You have used an RCD socket! Is this circuit not already RCD protected in your CU? If it is you don't need an RCD socket.

 

[JohnW2]

You have used an RCD socket! Is this circuit not already RCD protected in your CU? If it is you don't need an RCD socket.

That comment is s bit moot for this OP. It's already been done, and there is no harm in it being an RCD socket even if it doesn't need to be. In fact, there's a chance (although no certainty) that a fault in the greenhouse might ('conveniently'!) trip the greenhouse RCD but not the house one (if there is one).

 

[LeadFarmer]

You have used an RCD socket! Is this circuit not already RCD protected in your CU? If it is you don't need an RCD socket.

Only because I already had one, so didn't see the point in going out and buying a non RCD socket.

 

[LeadFarmer]

I tend to wonder if you need some sort of cable restraint, after all your only glanded into a plastic box.

I'm going to fit more pieces of timber just like the one you can see, positioned along the run of the cable, and use cable clips to hold the cable in position, then there wont be any forces putting strain on the cable