Four core or five core for linking outbuildings with 3 phase

[zsalya]

I am laying pipes and cables (separated in accordance with local regulations) underground between outbuildings, and will then close up various trenches.
Between one pair of outbuildings I want to connect 3-phase power (they are currently linked by 4 overhead wires, but I have disconnected everything further downstream because it was not safe)
In case relevant, both outbuildings have lightning conductors.

I will get in someone who understands 3-phase properly to do all connections, but my question at this stage is: for the underground cable should I lay 4-core or 5-core?

i.e. Does 5-core give flexibility for the expert to decide how to do the earthing later, or is 4-core always enough because the earthing has to be done separately at each building?

 

[cliffed]

5 core might sound better,it’s the actual Earth & Main bonding @ the intake that needs,thinking about.
If the earthing is going to be different,the tt system may be the option.

 

[ferg]

We are mostly UK based sparks so rules and regulations may be different where you are located.

 

[Pete999]

I am laying pipes and cables (separated in accordance with local regulations) underground between outbuildings, and will then close up various trenches.
Between one pair of outbuildings I want to connect 3-phase power (they are currently linked by 4 overhead wires, but I have disconnected everything further downstream because it was not safe)
In case relevant, both outbuildings have lightning conductors.

I will get in someone who understands 3-phase properly to do all connections, but my question at this stage is: for the underground cable should I lay 4-core or 5-core?

i.e. Does 5-core give flexibility for the expert to decide how to do the earthing later, or is 4-core always enough because the earthing has to be done separately at each building?

Matey, you would be better advised to contact some Local Polish Electricians, who are conversant with the Polish requirements for electrical installations, with all the best will in World, many Brit Electricians would be comparing British Regulations to help with your conundrum, any how all the very best luck hope you get the advice you require.

 

[Deleted member 26818]

I once had to work on a Polish machine.
The Neutral was connected to Earth inside the machine.

 

[Pete999]

I once had to work on a Polish machine.
The Neutral was connected to Earth inside the machine.

See post 4 for advice then

 

[cliffed]

Love Krawco

 

[Pete999]

Love Krawco

That would mean Krakow I presume?

 

[shaun1]

In addition to earthing conductors, you also need to consider load requirements and the length of each of these cables to work out what size you need. These calculations could get complex, especially if the power links from building to building, as the load will increase at each building as yiu work back to the souce.

As others have said, it is best to get the person who will be making the final connections involved at this stage so they can make sure the correct size and type of cable is installed.

 

[Pete999]

In addition to earthing conductors, you also need to consider load requirements and the length of each of these cables to work out what size you need. These calculations could get complex, especially if the power links from building to building, as the load will increase at each building as yiu work back to the souce.

As others have said, it is best to get the person who will be making the final connections involved at this stage so they can make sure the correct size and type of cable is installed.

Agree if this was in the UK , but the OP is in Poland where the rules and Regulations may not be the same as in the UK just saying.

 

[shaun1]

Agree if this was in the UK , but the OP is in Poland where the rules and Regulations may not be the same as in the UK just saying.

Very true but the scientific principals will be the same so I would imadgine the calculations will be similar, and necessary in some form. Either way local advice is needed as you said above, I just thought it worth mentioning that there is more to it than just earthing incase the OP is not aware.

 

[Lucien Nunes]

The Neutral was connected to Earth inside the machine.

Genuine TN-C (neutral and earth combined all the way to the load). Quite common in mainland Europe at one time. Our nice 1950s Swiss horizontal borer was wired that way originally.

 

[Pete999]

Very true but the scientific principals will be the same so I would imadgine the calculations will be similar, and necessary in some form. Either way local advice is needed as you said above, I just thought it worth mentioning that there is more to it than just earthing incase the OP is not aware.

May well be correct Shaun, but when in Poland do as the Polish Sparkies do

 

[zsalya]

All true, but I'm regarding Polish regulations as necessary rather than sufficient to be safe.
E.g. over here:
1) Back "boxes" are flimsy plastic cylinders, so removing a plug often brings the socket with it, even in a five star hotel in Germany,
2) Metal lamps old and new (no double box symbol in sight) are sold with two pin plugs,
3) One half of nearly all domestic internal double sockets fail a UK polarity test,
4) For the local harvest festival the power was tapped from a pole in the field. I challenged its safety and was told the distribution company had done it!

 

[Deleted member 26818]

Was it Russians or Poles twisting the wires together with a drill in one of Pete’s videos?