Why Didn't 20A Type C Fuse Trip With 10,350W Load in Old Hut Electrical System?

Hello everyone, I am asking for your advice.
Today an electrician started modifying the electrical system in the old hut I rented.
Only one phase is connected to the house, and in the box above the meter I have a 20A type C fuse - that is, from what I read on the Internet, up to 20A can be connected about 4600 W.

However, after the first modification (consisting only in making a separate circuit inside the house for the bathroom), I wanted to check whether the installation would withstand all the receivers we have and ... durable. No security fired.

After counting the power of the devices, it surprised me because I connected:
- boiler - 2000W
- laundry dryer - 2700W
- pump in the well - 1300W
- freezer - 200W
- microwave - 750W
- heater - 1500W
- angle grinder - 750W
- circular saw - 1150W
The last three as substitutes for various devices that I do not have at home yet - my wife's dryer, electric kettle, etc.
As you can see, this gives a total of 10 350W. The devices worked for about a minute.
In the box with fuses inside (not yet modified except for adding one fuse) there are currently 20A type B protections. The wires inside the house are 2x 2.5mm Cu.

How is it possible that no security has fired? Is it safe to use this installation under such a load?
I am asking for advice.

Current-time characteristics
and it will light up a little.

Exactly. Read about the time-current characteristics of the miniature circuit breakers. If you could withstand such a load for a while longer, it would most likely turn off this C20 (if it is functional).

Maciek W wrote:

In the box with fuses inside (not yet modified except for adding one fuse) there are currently 20A type B protections. The wires inside the house are 2x 2.5mm Cu.

That's not good. Currently, the maximum 2.5mm2 Cu protection switch that can be used is In = 16A (of course, on the condition that the power supply is automatically turned off)

Maciek W wrote:

As you can see, this gives a total of 10 350W. The devices worked for about a minute.
...
How is it possible that no security has fired? Is it safe to use this installation under such a load?

The phenomenon you have simulated is overload - for your total load of 10kW, 1-f current of about 45A. From the time-current characteristics of the over-current protection C20, it can be read that for a current of 45A, the overload release time is about 25s. After this time, theoretically, it should trip the pre-meter protection.
The reason for not releasing this security could be:
- too short load time of the protection with a current of 45A, for example by not simultaneously switching devices on,
- incorrect calculation of the actual total power of the devices - you would have to measure the current on the phase with a clamp meter,
e.t.c.

Are you on your el. were the appropriate measurements made by an electrician?

Maciek W wrote:

How is it possible that no security has fired? Is it safe to use this installation under such a load?

The contractual, upper tripping current of the overcurrent circuit breaker is 1.45 of the rated current, ie approx. 23A.
And the contractual tripping time of circuit breakers up to 63A is not more than 1 hour.
That is, the excess load time is too short to trip the installed circuit breaker.
And for a double overload current of the thermal release, it will be difficult to calculate the maximum operating time, but it will definitely be longer than 1 min.
Thermal releases operate in the band from 1.13 to 1.45.

Such experiments and trials in the long run will not be very kind to an electric wire, the insulation of which degrades faster and its service life decreases.

Good advice, or reduce the fuse value to 16A and replace the power cord with YDYżo 3x4 mm2.

voytalo wrote:

Exactly. Read about the time-current characteristics of the miniature circuit breakers. If you could withstand such a load for a while longer, it would most likely turn off this C20 (if it is functional).

Well, of that Link it seems that before the C20 shoots with such an overload, it takes about a minute - so maybe the devices worked a little shorter - as long as the fuse is in working order.

Quote:

That's not good. Currently, the maximum 2.5mm2 Cu protection switch that can be used is In = 16A (of course, on the condition that the power supply is automatically turned off)

So I am replacing it with 16A

Quote:

The reason for not releasing this security could be:
- too short load time of the protection with a current of 45A, for example by not simultaneously switching devices on,

they were all turned on practically at the same time - I can try again

Quote:

- incorrect calculation of the actual total power of the devices - you would have to measure the current on the phase with a clamp meter,
e.t.c.

I wrote down the power from the rating plates / stickers of devices or instructions. The only measure I have is this invention: Link
but it's a meter, not a meter, although it shows the instantaneous power consumption in watts.

Quote:

Are you on your el. were the appropriate measurements made by an electrician?

Unfortunately no, it's an old log cabin where the installation was renovated some time ago, but it doesn't look very good anyway. I would prefer to avoid having it completely replaced because of other costs I have to pay, but certainly not at the expense of security.

What is the possible maximum current consumption (with prolonged use) with such protections?

I would like to know, before I bring my wife and children to this house, whether there is a need to do some major perestroika in the installation or whether it can stay as it is. In total, in the "comfort option" 9 without choosing what should work at the moment and what not), I must be able to use devices with a total power of approx. 8 kW at the maximum.

Added after 6 [minutes]:

.Jack wrote:

Good advice, either reduce the fuse value to 16A or replace the power cord with YDYżo 3x4 mm2.

So e.g. such? Link

Solomon does not drink from the empty one.
All you have to do is ask the energy supplier to increase the ordered power and then increase the cross-section of the power cable according to the new power. There may also be a need to replace the energy meter and, of course, the pre-meter protection.

I greet everyone

jjanek

jiwaniuk wrote:

Solomon does not drink from the empty one.
All you have to do is ask the energy supplier to increase the ordered power and then increase the cross-section of the power cable according to the new power. There may also be a need to replace the energy meter and, of course, the pre-meter protection.

I greet everyone

jjanek

Not necessarily. Besides, the author mentioned that the installation is in a rented "cottage", so this solution is not an option. After all, not all receivers will work at the same time, and even if most of them will be turned on at the same time and the switch will trip, you can try to separate priority circuits and less ones and cover them with a priority relay.

Some magician figured out something strange with this installation. I think when replacing the meter - now it is electronic (the owner did it some time ago), the wire going from the meter to the house was also replaced. The piece of the tube in which it goes is chipped, so you can see that this new wire is white - probably copper (I have no way to check the cross-section because there is no vein on top), while the old one is coming to the main can in the house from which everything comes out black aluminum cable 2x4mm. Since the cable enters the house, it goes under the paneling - for a distance of approx. 5 m (from the place where it enters the house to the box), so you cannot see where they connect. Assuming that the copper cable has similar parameters to the aluminum one - how many amps can be safely passed through the AL 2x4mm cable?

Added after 10 [minutes]:

voytalo wrote:

Not necessarily. Moreover, the author mentioned that the installation is in a rented "cottage",

All you need is a cottage, without "", because it's really an old country cottage :)

Sorry, when I wrote 2x4mm (after more precise measurement it was about 3.5 mm) I meant the diameter of the aluminum wire, so it turns out that the cross-section of such a wire is about 10mm2.

Are you sure that each of these devices has developed its rated power? The current consumed could be much smaller than you expect.

Later I checked individual devices (I only have a meter up to 3kW) and only the boiler consumed significantly = 1200W. The rest were either drawing full power or slightly less (e.g. 2500 dryer instead of 2700).