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How to select RCCB?

Hello friends, this post is very important. In this post, we will talk about how to select the rating of the RCCB. When we see any RCCB, there are two ratings written on it. For example, on the first RCCB 25A written with 30mA and on the second RCCB 25A written with 100mA.

30ma 100ma rccb

Mean both RCCB is of 25A and with it one is of 30mA and the other is 100mA. So what are these 30mA and 100mA? We will talk about this in today’s post.

What is 30mA, 100mA and 300mA on RCCB?

Friends, first of all you have to keep in mind that your 25A means how much load you can connect your RCCB. If more than 25A current pass then our RCCB will not work and it can damage.

We decide whether we have to put 25A or 50A as we decide rating of MCB. If MCB is being installed and then we can also install RCCB of the same rating of which MCB is installed. For example, if MCB of 16A is being installed then you can install RCCB of 16A only.


Now you will think that what is second rating of RCCB and which rating RCCB where is used.

How to select mA rating of RCCB?

Friends, this second rating is called the sensitivity range of RCCB. Means that our RCCB is how sensitive our second rating tells us. We should also clarify that there are only three sensitivity ranges of RCCB in the market: 30mA, 100mA, and 300mA.

How to select mA rating of RCCB?

Now the next question will come to everyone’s mind which rating we should put RCCB. Friends, this question can also be asked to you in the interview, after which RCCB with which sensitivity is installed.

Where to use 30mA RCCB?

If we talk about 30mA RCCB, then we put this RCCB where the direct touch of the load with our body. For example, if we talk about our house, then our fridge, washing machine, etc. we touch them directly. So in such a place where we are directly touching again and again, at that place we put RCCB of 30mA.


If we understand in simple words, then we use RCCB of 30mA, where we need a lot of protection.

Example: We touch the fridge again and again in the house, now if there is a fault, the current start leak from the refrigerator and if we not installed RCCB, then if we touch the fridge there maybe we feel an electrical shock, Or if the RCCB that you have installed is a high sensitive range, then it will not trip quickly, due to which we will feel electrical shock and maybe we will die. So that’s why in such a place where we touch the load again and again, at those places we put high sensitive means 30mA RCCB.

electrical shock protection

Because friends 30mA RCCB is very sensitive. Meaning that this RCCB trips very fast when 30mA current leaks from our supply wire. If the supply wire touches our body, then in that case this RCCB will trip very fast. We use RCCB of 30mA where we need a lot of protection.

Where to use 100mA RCCB?

Now, if we talk about 100mA RCCB, we can also use this RCCB in our homes. But if you are asked in the interview where is its main usage, then you can simply say that 100mA RCCB is used where there is already Inherent current present. The digital devices that we have, like our laptops, have some leakage current inside all of them. We call this current as Inherent Current.

100mA RCCB

100mA RCCB is used where there are many digital devices such as call centers, data centers. Many digital devices are connected in all these places. Now you people will say that we have laptop computers even in our homes.

data center

So, friends there are only one or two laptops in the houses, but call centers are connected to many digital devices. Where we use many digital devices, we use RCCB with 100mA sensitivity range.

Where to use 300mA RCCB?

Now let’s talk about 300mA RCCB, so it used very less in homes. but if you ever go to the industry or go to a big hotel, then it is used because it is used for fire protection.

300 ma rating RCCB

Apart from this, for large machines where there is already leakage current, such as a welding machine or a cutting machine, then for these we use RCCB with 300mA sensitivity range. This RCCB is not used in homes because it does not protect us. If 300mA leakage current passes through our body then it can cause great harm to us.

We hope that you understand. If still any doubt or question remains then feel free to ask in comment section or you can ask this question on Instagram Electrical Dost”.

If you like to see videos of electrical engineering in Hindi language. then you can visit to our YouTube channel, Electrical Dost“.

Thank You 🙂

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