If you want to have a charging station or charging point installed, you will soon end up at your meter cupboard. After all, the charging station must be connected there, ideally to a free group. If you are going to charge on 3 phases, the earth leakage circuit breaker must also be checked. In some cases, you will need an additional earth leakage circuit breaker, the so-called ALS-B, or earth leakage circuit breaker type B.
In which cases do you need a type B earth leakage circuit breaker and when can you still charge on 3 phases without needing an additional ALS-B?
What does a residual current circuit breaker actually do?
An earth leakage circuit breaker detects voltage loss by measuring the outgoing and returning voltage. When there is (too great) voltage loss within the installation group, the earth leakage circuit breaker switches on immediately and de-energises the group. What the earth leakage circuit breaker actually does is switch off the entire group (de-energise) as soon as a leak is noticed. This makes the role of the earth leakage circuit breaker incredibly important, because it provides safety when voltage leaks from the network (which should never be possible, since the installation must be closed).
Residual current circuit breakers: type A and type B
There are many different types of residual current circuit breakers, but here we will only review type A and type B because they are relevant to your home installation or installation at your company (unless you work with enormous amounts of voltage of course). The type A residual current circuit breakers are only intended for installations with alternating current with amounts of leakage current up to a maximum of 6mA.
When you start charging electrically, you usually exceed the 6mA limit. The result is that an ALS-A cannot measure the leakage current and is therefore unsuitable for the group that is used to supply the charging station with power. That is why an ALS-B must be chosen, which can measure DC leakage current (direct current) in addition to leakage currents up to 6mA. Now, this is not just advice; it is a rule drawn up by the IEC (International Electrotechnical Commission). It states that a type B earth leakage circuit breaker must always be used when charging an electric car on 3 phases. The reason for this is obvious: if the fault currents cannot be detected, life-threatening situations can arise and this must be prevented.
There is, however, an exception where you are allowed to use a type A earth leakage circuit breaker for the group used for charging on 3 phases.
A charging station with earth leakage protection
Modern charging stations usually have a built-in earth leakage protection with DC leakage current detection. If you opt for a charging station or charging station that is equipped with its own ALS, you can simply place it behind an earth leakage circuit breaker type A. The ALS in the charging station then already takes care of the detection of DC leakage current. An additional DC leakage current detection is then unnecessary and does not help with safety.
When is an earth leakage circuit breaker B mandatory?
There are two cases when charging electric cars where a type B earth leakage circuit breaker is mandatory:
- Charging on 3 phases with a charging station or charging point without its own earth leakage circuit breaker
- Charging the Renault Zoe
When charging the Renault Zoe, a type B earth leakage circuit breaker is mandatory because there is no galvanic separation between the car itself and the charger. In concrete terms, this means that the charger can come into contact with other electrical parts of the car, which greatly increases the risk of fault currents, which can be a major safety concern. It has therefore been decided that a Renault Zoe may only be charged on a group that is protected by a type B earth leakage circuit breaker.
Is it wise to choose a type B earth leakage circuit breaker?
You can choose to have a type B earth leakage circuit breaker installed, but first take a good look at the costs and benefits. A charging station or charging station with a built-in earth leakage circuit breaker may cost a little more, but a type B earth leakage circuit breaker is also considerably more expensive than an ALS type A. Also include the installation costs in your calculation, so that you get a fair picture of your options.
In the case of a Renault Zoe and charging on 3 phases with a charging station without built-in earth leakage protection, you are in any case stuck with an earth leakage circuit breaker type B.
