A very long extension.

[thaibeachlovers]

I want to put a power supply to a shed about 30 meters ( perhaps more ) from the nearest 3 pin mains plug. I know I have to use a larger than normal cable.

 

Do I have to use 3 core including earth or can I earth the shed using a rod and just 2 core cable for + and -? I need 3 pin sockets and loads of lights in the shed. Main use of the power will be power tools.

 

I have a breaker unit already for mains and light circuits, so just need the cable.

 

Any help much appreciated, thanks.

[Ralf001]

 

[Olmate]

Sheep shearing! thats nice.

[thaibeachlovers]

1 minute ago, Olmate said:

Sheep shearing! thats nice.

 

3 minutes ago, Ralf001 said:

 

Thanks for replying on topic.

[sometimewoodworker]

13 minutes ago, thaibeachlovers said:

I want to put a power supply to a shed about 30 meters ( perhaps more ) from the nearest 3 pin mains plug. I know I have to use a larger than normal cable.

 

Do I have to use 3 core including earth or can I earth the shed using a rod and just 2 core cable for + and -? I need 3 pin sockets and loads of lights in the shed. Main use of the power will be power tools.

 

I have a breaker unit already for mains and light circuits, so just need the cable.

 

Any help much appreciated, thanks.

You need to specify the number of tools that will be in use at one time and the power consumption of them, as the answer will be very different between a 350w drill and a 3000w table saw and 1500w chip extraction unit running simultaneously 

[thaibeachlovers]

10 minutes ago, sometimewoodworker said:

You need to specify the number of tools that will be in use at one time and the power consumption of them, as the answer will be very different between a 350w drill and a 3000w table saw and 1500w chip extraction unit running simultaneously 

Thanks for replying. As it's just me, only one power tool at a time, so consider using the largest table saw on the market and go for that. I'm only guessing at the exact distance- could be 50 meters, so make your calculation based on that. I don't mind going over what is needed.

[Crossy]

Let's say 20A at 50m then you are looking at using 4mm² cable, any longer and you need to go to 6mm².

 

RCD/RCBO at the supply end.

 

To save a few $$$ make it a "TT island" by using 2-core cable and placing a ground rod at the shed. Note- Do NOT provide a N-E bond at the shed end. 

[Olmate]

1 hour ago, thaibeachlovers said:

 

Thanks for replying on topic.

Just speculating on the "tool" you intend using.Those 240v shearing settups are quite heavy on power.

[thaibeachlovers]

1 hour ago, Crossy said:

Let's say 20A at 50m then you are looking at using 4mm² cable, any longer and you need to go to 6mm².

 

RCD/RCBO at the supply end.

 

To save a few $$$ make it a "TT island" by using 2-core cable and placing a ground rod at the shed. Note- Do NOT provide a N-E bond at the shed end. 

Thanks again.

You answered the question I had not asked, about the N-E bond. I asked an electrician about that but I was unable to understand his answer- far too technical. I even looked it up on the internet, but again far too technical for me to understand.

I can't get my head around the idea that N and E can be bonded but not provide a short to earth.

 

 

[Crossy]

Have a look at this page https://en.wikipedia.org/wiki/Earthing_system

 

Thailand is generally TNC-S with MEN (Multiple Earthed Neutral), the neutral is held at or near earth potential by having a ground rod at every 3rd pole or so along with every installation having a local rod and N-E bond.

 

There can only be one N-E bond in an installation. 

 

A N-E bond placed on the downstream side of an RCD/RCBO will generally result in the RCD not staying closed, or if it does stay on then applying any load will cause it to trip.

 

 

[thaibeachlovers]

On 4/10/2025 at 3:24 PM, Crossy said:

Have a look at this page https://en.wikipedia.org/wiki/Earthing_system

 

Thailand is generally TNC-S with MEN (Multiple Earthed Neutral), the neutral is held at or near earth potential by having a ground rod at every 3rd pole or so along with every installation having a local rod and N-E bond.

 

There can only be one N-E bond in an installation. 

 

A N-E bond placed on the downstream side of an RCD/RCBO will generally result in the RCD not staying closed, or if it does stay on then applying any load will cause it to trip.

 

 

Thanks again. I'll take your word on that, as I get confused easily by technical things these days.