3-phase charging on IT grid with Zaptec Go

In short

  • Zaptec Go supports charging on TN / IT / TT system, including 1-phase and 3-phase.
  • Using 3-phase power on IT-system will generally charge your electric car faster, but not all cars support this. 
  • Lower charge power can be beneficial for the electricity bill, to help you cut down on your network tariff. 

If you're not sure which electrical grid you have at home, you can check this in the fuse box. Normally, the cabinet will be marked with, for example, "IT" (230V), "TN-C" (400V) or "TN-S" (400V).
If you cannot find this you can check the intake fuse/circuit breaker or contact an electrician.


Power systems and on-board chargers (OBC) 

In Norway, we have three different power distribution systems: 

  • TN 400V
  • IT 230V
  • TT 230V

If you are connected to a 3- phase TN- system (400V) you have few restrictions on power during charging. If you are on a 3-phase IT or TT-system it is the on-board charger in your car that determines the utilization of the phases, and this affects the effect - that is, how quickly you get charged (kW).

☝️ The differences only apply to 3-phase systems. If you have 1-phase into the house, the maximum charging power will be the same for all grid systems.


Effect and safety 

Charging stations from Zaptec work with both 1- and 3-phase, and support charging up to 22kW, depending on which grid system you have.

How fast the vehicle can be charged will be affected by several factors. 

E.g. In a 3-phase system the general rule of thumb is to check that the power grid, charging station, charging cable and the on-board charger (OBC) support 3-phase charging.
If not, it will be 1-phase. 


The table underneath shows the maximum charging power for different power grid, installation, charging cables and cars. Notice that the charging effect will be governed by the weakest of the four factors below. In the table, this weakest factor is marked in red. 


With a IT /3-phase system the maximum potential power would be 12,7kW, but there are currently no cars that fully support charging on IT /3-phase. Tesla Model 3 or Y is the car model that chargers fastest on IT/ - phase today and it only manages to utilize 11kW. 

All other cars that support partial charging on IT 3-phase can have a maximum advantage of 1kW in charging speed, which corresponds to 0.5 miles charged per hour. However, the majority will be able to get 7,4kW (32A/1-phase) in an IT network. 


Safety first 

The charger will automatically detect how many phases it is connected to. If it is connected as 3-phase, it will pass through all three phases and correspondingly if it is connected 1-phase. 

The reason for this is that there is a requirement for an all-pole break in the safety relay for the earth fault circuit breaker, meaning all 3 phases are ON or OFF at the same time. Put in another way, the charger will not be able to switch from 3- to 1-phase automatically, in accordance with safety regulations. 


Awesome, you think, but what does this actually mean for you as a user?

Since TN network is ready to handle all electric cars, this is only relevant it you have a three-phase IT network, as well as a car that does not support charging to these specifications. 


The Go charger will detect that current is only drawn on one phase and then allow charging up to 32A/7,4kW. The exception will be where 1-phase cars does not charge on IT 3-phase at all. 

In that case, you must decide whether you: 

1) want an electrician to install the chargers as 1-phase, or
2) that you use a 1-phase charging cable as a bottleneck for power. In these circumstances, regardless of choice, you will be able to get a maximum output of 7,4kW. 



For those of you who have two cars, where only one of them supports 3-phase charging on IT, then the last alternative would probably be the best. In this way, you still have the option of charging with three phases. 


Power peaks 

1-phase charging is usually sufficient for your daily charging need.

In conjunction with the new tariff for electricity costumers (from 01.07.22) it can also be seen that it is possible to only use 1-phase charging even if the car supports three-phase. This is to avoid the higher power peaks. 

Below you can see an example of how this can turn out: 

If you have an electric car and charge at home, you will quickly end up at 
stage 3 (5-5kW)
or 4 (10-15kW). The cost still vary from company to company.
At BKK, it costs NOK 350 per month at stage 3 and NOK 494 at stage 4, including VAT.
At Lyse, the prices are NOK 350 and NOK 475 respectively.

Source: BKK, Lyse, House owners in Elbil24.no 




How can I find out if my car supports 3-phase charging on IT? 

Contact the car manufacturer for more information. 


What happens if I use a 1-phase cable on a 3-phase charger? 

The charger will detect the capacity of the charging cable that is connected. E.g. If you use a 1-phase cable on a 3-phased wired charger it will behave as if it were connected to 1-phase. 





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