Washer & Dryer on One 4-Wire Cable: Safe Connection by Electrician Uncle Czesiek? (2.5mm2, B16)

Hello
An old-time electrician, "Uncle Czesiek", ran one cable under the washing machine and dryer for the bathroom four-wire with a cross-section of 2.5mm2. The devices operate on separate phases, the neutral conductor is common. In the box, the phases are protected with B16 circuit breakers and above them with a 25A differential.
Somehow I do not see it fully, I do not know why he did not let go of two separate wires, but he says that it is good.
Will this connection work safely?

From the device manuals:
Washing machine: rated power 2300W, rated current 10A,
Dryer: max connection power 2800 / 2100W, fuse 16 / 10A

omaral wrote:

Will this connection work safely?

No, it won't be right.
On one wire you have two independent power circuits (from other fuses) so you must not.
There should be two independent circuits and wires for these receivers.

It's already done and finished so I can't do much here.
Can the devices work simultaneously?
What can happen if the devices work simultaneously?

omaral wrote:

It's already done and finished so I can't do much here.

You should have asked before, not after the fact.
It can't be like that.

If you let an electrician in, you rather assume that he knows what he is doing - I don't know anything about it and only now I noticed it.
"Uncle Czesiek" is not in the profession for a while, but he was even licensed in the past, so I don't know why he did something that seems strange to a layman.
So I will repeat the question:
Can the devices work simultaneously?
What can happen if the devices work simultaneously?

The answer: "It can't be like that," tells me nothing.

omaral wrote:

Can the devices work simultaneously?

How are they powered? One phase or two?
If the cross-section is too small on one of the two, the cross-section of the two is sufficient. Which does not change the fact that the installation is incorrect and dangerous to health and life.

Added after 2 [minutes]:

omaral wrote:

Answer: "It can't be like that," tells me nothing.

Just because he doesn't tell you anything doesn't mean you can, it's just forbidden and there's no point in philosophizing.

As I wrote, wires with a diameter of 2.5mm2. One black wire goes to the current from one phase, fuse B16, the other brown wire goes to the current from the other phase and also B16. Common return with one blue wire. And the yellow-green wire. Three-phase differential.

kokapetyl wrote:

omaral wrote:
Answer: "It can't be like that," tells me nothing.

Just because he doesn't tell you anything doesn't mean you can, it's just forbidden and there's no point in philosophizing.

Nothing says about possible actual consequences and unfortunately spartolone is already there.

So what can happen when using two devices at the same time, someone will suggest something?


But wait a minute, induction and oven are commonly connected on one 5-wire cable, where two phases go to induction and one to the oven and the neutral is common, and that's how it works.

On this forum I found this statement:
Link
"Generally, your phases are shifted by 120 degrees. If you have the same current consumption in all phases at the same time, something" magic "will happen, i.e. instead of seeing the current three times greater there, you will see ... zero This is used in symmetrical loads, to which you do not lead N. Assuming sinusoidal current waveforms, in the N conductor you will see the worst case current of any phase (while the others are off), or the resultant of these currents, but as a geometric sum, and not arithmetic.
The problem begins with non-linear receivers, containing numerous harmonics, because some of the harmonics cancel out, and some add up ... "

So I conclude that nothing will happen, am I right?

Hello.
Uncle Czesiek knew what he was doing. Everything is OK.
I guess you are worried about the current in the neutral conductor when working simultaneously? Unnecessarily.
It will be a vector sum, not an algebraic phase of the phase currents.

Moderated By Łukasz-O:

3.1.11. Don't post messages that add nothing to the discussion. They are misleading, dangerous or do not solve the user's problem.

This is how I was afraid that the sum of the currents from the two phases would flow through the neutral wire, which the wire might not withstand.
Theoretically, if the washing machine pulls 10A on L1 and the dryer pulls 12.17 on L2, what current to expect on the neutral?

Added after 10 [hours] 3 [minutes]:

I added the parallelogram method two vectors 12.17A and 10A long coming out of one point at an angle of 120 degrees to each other and it came out about 11.38A. Can such a current be expected on the neutral conductor with the simultaneous operation of these devices?

Consider whether the washing machine heats the water at the same time (the highest power consumption) and the dryer dries the clothes.

Welcome back.
More or less will. Looking at the sinusoidal waveform, three-phase voltage (the current waveform will be analogous), the instantaneous value for two
(any phases) will be approximately 50% of the sum of the algebraic values of these phases.
In summary, Uncle Czesiek made the installation as correct as possible.

Moderated By Łukasz-O:

3.1.11. Don't post messages that add nothing to the discussion. They are misleading, dangerous or do not solve the user's problem.
Warning.

Uncle Czesiek did it wrong.
He did not take into account the recommendation (Journal of Laws 2002 No. 75 POZ. 690, as amended) that single-phase receiving devices with a power of more than 2 kW should be on separate circuits.
The above-mentioned case contradicts this, because the common N conductor is a common circuit, despite a separate protection.

elpapiotr wrote:

Uncle Czesiek did it wrong.
He did not take into account the recommendation (Journal of Laws 2002 No. 75 POZ. 690, as amended) that single-phase receiving devices with a power of more than 2 kW should be on separate circuits.
The above-mentioned case contradicts this, because the common N conductor is a common circuit, despite a separate protection.

The moderator is right.
I focused on the load on the neutral wire, which is not the same as the correct power supply to receivers of this power.
Summing up, the neutral wire will not be overloaded, but the installation is not in accordance with applicable regulations.

fala591 wrote:

I focused on the load on the neutral conductor ...

It is not at all certain that there are two unlike phases shifted by 120 °.
Some even say that there are two phases to a chandelier controlled by a candlestick switch. They are only identical!
This may be the case of the Author and then the current in N is added algebraically, which, while using both receivers with full power, will lead to the exceeding of Idd.

Zbych034 wrote:

Consider whether the washing machine heats the water at the same time (the highest power consumption) and the dryer dries the clothes.

Why not? More people in the family and the laundry has to be done in two or more cycles. The first cycle dries and the second washes ...

zbich70 wrote:

Zbych034 wrote:
Consider whether the washing machine heats the water at the same time (the highest power consumption) and the dryer dries the clothes.

Why not? More people in the family, and the laundry has to be done in two or more cycles. The first cycle dries and the second washes ...

And is the heater on all the time the washing machine is running? And during spin also?

karwo wrote:

And is the heater on the entire time the washing machine is running? And during the spin also?

No, just at the beginning.
That is exactly when the previous laundry just started to dry ...

elpapiotr wrote:

Uncle Czesiek did it wrong.
He did not take into account the recommendation (Journal of Laws 2002 No. 75 POZ. 690, as amended) that single-phase receiving devices with a power of more than 2 kW should be on separate circuits.

You write "recommendations", so are they requirements or recommendations? And how does this relate to connecting an induction and an oven on one cable - also incompatible? A commonplace.

omaral wrote:

A commonplace.

Performed by Janusz and Grażyna, they are met.
Never performed by an electrician made of flesh and blood.

omaral wrote:

And how does this relate to connecting an induction and an oven on one cable - also incompatible?

Of course not compatible because it is an outlet for a 3-phase cooker.

I would save myself from such a situation with the use of a priority relay - the washing machine works -> the dryer does not work ...

Perhaps a washing machine and dryer simulator would be an ordinary kitchen. In them - depending on the type and manufacturer - all connection combinations are used.
This is illustrated by the following drawing taken from the manufacturer of the device - an induction hob:

Podłącze..e.png Download (85.98 kB)

Another example is a gas cooker with an electric oven or a cooker with a ceramic hob and electric oven - the connection diagram is identical.

podłączen.. 2.png Download (84.61 kB)

"The kitchen is factory-adjusted to be supplied with three-phase alternating current (400V 3N ~ 50Hz). The rated voltage of the kitchen heating elements is 230 V."
In fact, the manufacturer stipulates that the board is three-phase 400 V, but the heaters are 230 V (he gives contradictory information). In fact, these are 230 V devices, but powered from three, two or one phase and not phase-to-phase. Information about 400 V can be misinterpreted (and probably it happened more than once)!

Why am I giving you an example of a kitchen? Well, because kitchens are available in variants: combined in one device and separate as two devices.
The same is the situation here with the two appliances in the form of a washing machine and a dryer.
The issue here is that each device should have a separate power cord - this is what the regulations say and here it is consent.
On the other hand, to the question asked from the technical point of view, the answer in the above context may be that a washing machine and dryer on one four-core power cable (but two phases) is an identical technical example as a kitchen with a ceramic hob and an electric oven powered from two phases (one supplies the hob and the other an oven). Other combinations also come into play here.
Technically there is no difference. Both the hob and the oven use a common N conductor (the manufacturer has not separated the hob and oven circuits and there are no separate N conductors, but such a situation will occur with two separate devices, e.g. an oven and an electric hob). Thus, according to the regulations, they do not have separate power circuits. However, physically it is one device (two functional devices in one housing), which makes such a hybrid compliant.

Therefore, the answer to the author's question whether, when it is as there is any problem with operation in the technical sense, it should be answered that it will work. The main thing to pay attention to is the cross-section of the cable cores in relation to the power of the devices, which in total is 4400 W.
It is worth paying attention to the above diagrams, how the cable cross-section changes depending on the combination of heater connections. The manufacturer of a kitchen with a ceramic hob and electric oven allows a single-phase power supply, but then the cable cores are to be 4 mm2. The maximum power of the device is 10 kW.

Regards!

The author of the topic clearly writes that the washing machine and dryer are two separate single-phase devices and this is how it should be considered without combining how a Pole can.
In 1-phase circuits, we use 1-phase RCDs and please take this information into account.

omaral wrote:

Somehow I do not fully see it, I do not know why he did not let go of two separate wires, but he says that it is good.
Will this connection work safely?

It won't be safe, on the contrary. It will be very dangerous. If the washer and dryer are powered from the same phase, the neutral wire will be significantly overloaded, risking burning it with the risk of fire.
If, on the other hand, the phases are different, then a break in the N conductor will supply the washing machine and the dryer with interfacial voltage with the voltage distribution depending on the ratio of their instantaneous power. This can destroy both equipment.
I remind you that Murphy's law says that if something can break, it will for sure break, and at the moment when it will be the least suited to us.
(Others say that if a few things are likely to go wrong, the one that causes the most damage will fail.)

retrofood wrote:

It won't be safe, on the contrary. It will be very dangerous. If the washer and dryer are powered from the same phase, the neutral wire will be significantly overloaded, risking burning it with the risk of fire.

It seems that with the total power of the devices of 4.4 kW and the cross-section, the maximum power for the cable in the wall can be up to 25 kW. We only have 19 kW here, so there will be no fire threat. In addition, the total power will be consumed periodically and not constantly, so there is no risk in the sense of fire.



Regards

^ToM^ wrote:

retrofood wrote:

It won't be safe, on the contrary. It will be very dangerous. If the washer and dryer are powered from the same phase, the neutral wire will be significantly overloaded, risking burning it with the risk of fire.

It seems that with the total power of the devices of 4.4 kW and the cross-section, the maximum power for the cable in the wall can be up to 25 kW. We only have 19 kW here, so there will be no fire threat. In addition, the total power will be consumed periodically and not constantly, so there is no risk in the sense of fire.

1. There is no "cable in the wall" - there is a wire.
2. "Only" 19 kW, which is 3 kW above the limit.
3. "there is no fire threat" - you should receive a warning for such a statement, because you give advice without having a clue of what you are saying. Electrical installation is not only wires. It is also accessories, connections, protections, etc. All this has its long-term load capacity which usually does not exceed 16 A.

The statement "in the sense of fire there is no risk" can therefore only be written by a complete dilettante.

retrofood wrote:

1. There is no "cable in the wall" - there is a wire.
2. "Only" 19 kW, which is 3 kW above the limit.
3. "there is no fire threat" - you should receive a warning for such a statement, because you give advice without having a clue of what you are saying. Electrical installation is not only about wires. It is also accessories, connections, protections, etc. All this has its long-term load capacity which usually does not exceed 16 A.

The statement "in the sense of fire there is no risk" can therefore only be written by a complete dilettante.

I insist there's a cable in the wall after all. This topic has already been rolled out - a purely academic dispute.
Cable and cable
To put it simply: The electric cable is a conductor, it is insulated with one or more cores and surrounded by a common sheath.

If I had no idea, it wouldn't be possible for me to write it.
According to the table, (column A2) the permissible load is 18.5-19 kW (I was really wrong here because I read from the wrong column C where the external cables are - thanks for paying attention).
Since both of these items consume 19 kW in total, everything is within the acceptable limits. The table refers to the continuous power that a given conductor can conduct at a given current.
It wasn't advice. I shared the conclusions that follow from the table. I was only considering the cables themselves and not the entire installation in the building, its connections and leads, because I am not obliged to do so. The data in the table defends itself. My comment changes nothing here. If you have any comments on the table, you think it is wrong, please correct it - I will be happy to learn something new.