Which power cable / earth cable for 80 meters development

Hello everyone,

following situation: The supplier is laying a NAYY-J 4x50 cable, approx. 10 meters, on our property into a transfer cabinet. From here, we have to organize the rest of the development to the house ourselves. It is another 70-80 meters to the house. (House is being built in the third stage) The power requirement is 30kVA. Now we have received different statements and different offers from electricians. We were definitely recommended to use a copper cable.

Electrician 1 recommends at least an NYCWY 4x50 SM35 cable. Due to the length of 70-80 meters, he actually recommends taking 4x70, as otherwise there may be a voltage drop at this length and the 30kVA can no longer be guaranteed.

Electrician 2 recommends NYCWY 4x35 SM16. This would be completely sufficient.

Is E1 or E2 correct? What would you recommend I take?

Thank you in advance Müller

I'm not an electrician. But there are tables that show the cross-sections for that. Every electrician should be able to show you.

It is similar for us, 5x50qmm (with sufficient oversizing) was installed, 4-core cables are no longer installed in Berlin.

Hello everyone,

the following situation:
The supplier lays a NAYY-J 4x50 cable, about 10 meters, on our property into a transfer cabinet.
From here we have to organize the remaining connection to the house ourselves.
There are another 70-80 meters to the house. (The house will be built at the third stage)
The power requirement is 30kVA.
Now we have received different statements and different offers from electricians.
We were definitely recommended to take a copper cable.

Electrician 1 recommends at least an NYCWY 4x50 SM35 cable. Due to the length of 70-80 meters, however, he actually recommends taking 4x70, as otherwise there can be a drop in performance at this length and the 30kVA can no longer be guaranteed.

Electrician 2 recommends NYCWY 4x35 SM16. This would be completely sufficient.

Is E1 or E2 right? What would you recommend me to take?

Thank you in advance
Müller

The meter will probably then be in the transfer cabinet?

There will always be a voltage drop, or is the electrician suggesting superconducting cable?! The question is only how high it will be: If I calculate, for 70 meters of cable length and copper, I come to a voltage loss of

with 35 mm2
0.45% @ 10 KW per phase

with 50 mm2
0.31% @ 10 KW per phase

Just as a comparison – you will hardly use the full 30 KW, even with an electric car and/or photovoltaic feed-in.

You already lose 3 KWh with the thicker cable out of 1000 KWh. The difference in loss is about 1.5 per mille or 1.4 KWh per 1000 KWh consumption on top. That is the worst case at maximum power. If you demand less power, these percentage values decrease proportionally and the difference becomes even smaller! If you are going to lay the cable over such a long distance anyway, I would much rather take a slightly thicker KG pipe for the installation and also lay a thin cable – in case you want to pull another medium later, you have a) a nice empty conduit and b) a pulling aid and thus save yourself tens of thousands and a repaving of the driveway or digging up your garden. Better to have than to need for such a fat connection... ;)

Hello. I can respond here as an electrician since we have a similar situation.

The actual line loss is rather negligible here, at least for cross-sections larger than 25mm² up to 100m.

The crucial point is where the meter is installed. I assume it is installed inside the house. According to the Low Voltage Connection Ordinance (NAV), the voltage drop between the house connection (transfer point from the utility company) and the meter may be a maximum of 0.5%. With your 30kVA connection, probably a 50A fuse is installed in the house connection.

To comply with the 0.5% voltage drop, you would theoretically have to lay a copper cable with 95mm² at 70-80m.

That's the regulation. In practice, in my opinion, this is completely overdimensioned, especially since it would already be difficult to connect the 95mm² cable at all, as the terminals are usually not that large. I would try to go with 70mm² or 50mm². Ultimately, your electrician has to confirm to the utility company that he has complied with the regulations. If electrician 1 installs with 50mm², then it should not be your concern. Option 2 with 35mm² I consider too small for the cable length.

What surprises me is the cable type. It is absolutely fine to lay the cable with 4 cores and split it directly after the entry into the house to 5 cores if it comes from the utility company with 4 cores in the transfer box (as you wrote). An NYY-J 4x50mm² would be the right choice in this case because it is also cheaper than the NYCWY. However, it ultimately depends on the utility company. They have connection examples on their websites, best to check there.

Thank you very much for the answers.

@ : If I understood my supplier correctly, the electricity meter is in the transfer cabinet and not in the house. The electrician 1 also referred to this 0.5% voltage drop and therefore offered the line 4x70. The EVA is laying a NAYY-J 4x50 and not NYY-J 4x50 (you wrote) So an aluminum cable as shown to me on Google.

So E1 is definitely the right choice?

Now a general question of understanding: What exactly is the difference between 4x35 SM16 and 4x70 SM32? And why do you write that it has to be divided into 5-core in the house?

Thank you very much!