Main Security Difference: Electrical Installation with P304-25A, DeltaJ=0.03A & 20A Permit

Question

A simple question for professionals like you, but not quite for me. In the design of the electrical installation of a single-family house, I have the main protection and differential for all circuits P304-25A and deltaJ = 0.03A. Everything would be fine if the power plant did not issue a permit...

Ewaryst · Answer

At the beginning I propose to give a differential according to the design, then C20 es, and finally es for individual circuits.

andk1eltd · Answer

The current given on the differential is the rated current of the circuit breaker contacts - it can also be 100A. The delta mentioned above is important - max 0.03A.

Wakmen · Answer

Please, what a quick answer> I thought so too. 30mA (25A) 3-phase differential and C20A protection. Thank you very much for your quick reply.

Anonymous · Answer

If there is a project, the installation is to be done according to the project. Inserting an additional 20A switch (A, B, C or D) does not make sense either behind or before the differential. What, according to the project, is directly behind the difference? However, regarding the use of 3 differences. It is not a question of my own see me. It is recommended to use three RCDs, for example: 25A ?I = 0.03A - bathroom, 25A ?I = 0.1A 3-phase socket, 25A ?I = 0.03A other circuits.

Łukasz-O · Answer

The differential has nothing to do with it, it can be even 40A, it is not the main security and it cannot fulfill such a function. The most important thing for you is that the differential current is 30mA and the differential current rating is greater than or equal to the power allocation. You probably have a power allocation of 12kW or 3x20A and you must have such overcurrent protection in front of the meter.
Remember, the residual current circuit breaker only serves as an additional protection against electric shock and not against short-circuit (yes, there are versions with redundant members, but don't go deeper because that's not what it is about now).

max972 · Answer

The permission from the power plant is a bit strange, because typical is 25A. I would advise you to go to the power plant with this permit, because maybe there is simply a mistake in writing. The problem is that the rule is to apply protections to individual circuits two orders weaker than the main protection, e.g. main 25A, to 16A sockets. These 16A sockets are standard now. The design is correct and the installation should be made strictly according to it. As our colleague Łukasz-O rightly mentioned, the differential is an additional form of protection (very effective), and the overcurrent circuit breakers are the basic ones. And the delta value I = 30mA is the limit of self-release in case of electrocution, so building regulations clearly say 30mA max and not gaining more weight. For residential construction, a typical residual current device is 25A with delta I = 30mA, and an overcurrent circuit breaker is class B circuit breakers. The main protection is class C, which means that it is more delayed, so that in the event of a short circuit we can protect a circuit, and not everything.
And one more thing. Today, the installations for houses are designed in such a way that the main security and the meter are installed in a box placed literally in the fence of the property so that the master from the power plants can read the meter readily and that our beloved dog does not chew it, but only the rest, i.e. the differential and the protection of individual circuits is installed in the distribution box in the house. There are no additional overcurrent protections between the main fuse and the protections in the distribution box. And whether the protection is triple or single depends on whether we have a 3-phase or single-phase cable connected to the house. Today it is standard to bring a 3-phase installation to the house.
Regards

Wakmen · Answer

With this going to the power plant, there is no such need, because in the Tri-City, Energa from the end of last year for a connection capacity of 11kW (group V) has set (read - lowered) the main security to be 20A (previously it was 25A). And here it is all about that the construction project says its own (it was made according to previous nationwide arrangements) and the reality speaks its own. If I want to have more security, I have to increase the demand for kW to a higher one, but nobody heats the houses with electricity (only with other, much cheaper sources of energy). Added after 5 [minutes]: There is one main protection (25A) and one differential (as described above I = 0.03A) and there are individual circuits behind it. The problem (and maybe not the problem, only the ambiguity) lies between the new arrangements of the power plant in order to only collect the money for the next kW with the demand for energy.

Anonymous · Answer

And as he wrote max972 20A in front of the meter, it is also strange for me, you probably reported too little connection power demand. Usually it is 7.5 KW - 10.5 KW, that is 25 or 32 A. 20And I would say to a kiosk or a small shop, but not to your home. Added after 6 [minutes]: Hello, my colleague Łukasz-O , how does my colleague calculate that it is 3x20 for 12KW? If for 7.5 KW ZE they install esy 25A, and for 10.5 they install plugs (fuses) 32A?

HeSz · Answer

Andk1eltd and Łukasz-O are right. The 25 A current specified on the P 304 RCD, 25A 30 mA, is the rated current of the circuit breaker contacts and has nothing to do with the overcurrent protection. Therefore, additionally (as a protection against short-circuits) a 20 A pre-meter protection has been imposed. Differential will not trip even 30 A if it does not detect a leakage above 30 mA (at most it will be damned).

stomat · Answer

Exemplary connection of the connection capacity with the security value:

Łukasz-O · Answer

Hello, my colleague marcint2525 , I wanted to simplify, but good point, it should be 13.8kW. 20A or 4.6 kW x 3 phases gives a total of 13.8 kW. Does the colleague understand now Regards

Anonymous · Answer

Okay Łukasz, that's right. But why should the differential still protect the meter?

Łukasz-O · Answer

And who writes that the differential is to protect the meter? In the connection conditions, it writes about the differential, but it does not mean that it should be in front of the meter.

Anonymous · Answer

I did a bit of a run, but I have already met a circus performer who installed a residual current switch in front of the meter (in addition, he inserted a pin between the differential module and the switch so that they both turned off)! And what you wrote it smelled a bit like the differential in front of the meter. If you think I'm picking on me, then I'm sorry .

max972 · Answer

Hello.
Buddy, Wakmen. Either you have submitted a wrong demand for connected capacity, or your operator has an uninteresting policy towards consumers. In my city, in recent years, cooperatives have been installing 25A main protection in blocks, and in the apartment a 25A 30mA differential, 1x16A 3-phase, 3x16A sockets, 1x10A light. For a house, I would not even start with 20A, because it is a mockery and even if I were to design an installation for a house, I would be ashamed to give less than 25A. Maybe the whole house is not heated by electricity, but if we count a good ceramic kitchen + floor heating in the bathroom and possibly in the hall, which I see more and more often, in addition, the standard of the device is a washing machine, dishwasher, sometimes a welding machine in the garage + some other ideas and more lighting, is 25A too much? This is a house, not a flat in a block of flats. And anyway, after the de-monopolization of the en market. el. there was supposed to be competition, and so far the new operators have started to pay rises. And maybe the 20A for a colleague Wakmen is another macho on their part, because if he wants more, of course, but for a "small fee"?
Regards

Łukasz-O · Answer

Marcin - can I say that? I have also met "circus performers" more than once, amateurs of technical knowledge, which according to the law can be freely interpreted.

I really don't understand what my quote:

Quote:
You probably have a power allocation of 12kW or 3x20A and you must have such overcurrent protection in front of the meter.

has something to do with a residual current circuit breaker - could you please enlighten me?

I don't think you're picking on buddy, but you like to annoy me

Anonymous · Answer

My colleague max972 is most right about it. Protection 20A. No one has ever achieved 12KW from such security !!! for a single-family house !!! I have such devices at home: - 7.5 KW 3-phase engine - sawmill - 3-phase 4 KW motor - hydrophore pump - automatic washing machine about 2.2 KW - gas cooker with an oven 2.5 kW - electric bathroom heater 2.5 KW - electric boiler 2.5 KW - lighting and small acceptance of about 2 KW Adding up 7.5 + 4 + 2.2 + 2.5 + 2.5 + 2 = 23.2 KW. So what should my connection capacity be ??? ... According to the operator given in the link above, I should have 25 KW !!! Just what to the operator for this. ... and I have a 10.5 KW protection 32 A on threaded fuses (ordinary fuses). And when I applied for the conditions, no one asked what surface area I have and how many heaters, motors and other groups !!! Installation done last year (so probably in accordance with applicable regulations what? ). I also run an electronic service (in total, there is a computer, TV, radio, 4 soldering irons and a fan) and I have a single-phase 5 KW connection with 25 A protection.

Wakmen · Answer

I assure you that it is not so and no one even thought for a moment to do so. And so, unfortunately, is the ENERGA service provider. He just wants each new customer to ask for more demand as they need it. No electric heating. Gas in the border of the plot, so everything is on gas, even a gas hob, but the oven is not. It is a power nest in the garage, but only ... so that it would be e.g. for plasterers or floor planners. Nobody from the garage will build a sheet metal workshop . The larger electrical appliances are ... washing machine, dishwasher, TV, computer, dryer and iron. I guess that's it.

Main Security Difference: Electrical Installation with P304-25A, DeltaJ=0.03A & 20A Permit

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