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How to ensure fire safety of electrical wiring in an apartment and a house

 

How to ensure fire safety of electrical wiring in an apartment and a houseAccording to any, even the most superficial studies, faulty electrical wiring in the house or an apartment is dangerous, first of all, not because of the risk of electric shock, but because of the prospect of a fire.

No, of course, the danger of electric shock is not excluded, but a fire is no less likely, and when it occurs, it can immediately take more than one life and bring great damage. Therefore, when designing, installing and operating electrical wiring, you must not forget about some measures that can ensure fire safety and protect people from harm.


1. Measures to ensure fire safety of electrical wiring at the design stage


1.1 the selection of the brand of cables and wires prescribed for use in installation. For stationary installation in residential and non-residential indoor premises, the use of copper cables VVGNG or NYM. For portable power receivers and extension cords, PVA and ShVVP cables are suitable. The insulation of these cables does not spread combustion, and even in the event of overheating it cannot cause a fire. Aluminum cable is not allowed for use in installation, since contacts with the participation of aluminum conductors are more prone to loss of reliability and to the formation of an electric arc, which can cause a fire.


1.2 the choice of the cross section of the veins of cables and wires. The cross section should be selected according to the maximum load of the core, taking into account the permissible norm maximum continuous current. Moreover, this norm is not a constant value, it depends on the number of cores in the cable, the type of insulation and the method of laying the cable. Specific values ​​for the most common cross-sections of copper cables in PVC or rubber insulation are given below.



Cable cross-section of 1.5 square meters. mm

Paved open (regardless of the number of cores) - 23 amperes;

Paved hidden, two single-core - 19 amperes;

Paved hidden, three single-core - 17 amp;

Paved hidden, four single-core - 16 amp;

Paved hidden, one two-wire - 18 amp;

Paved hidden, one two-core - 15 amp;


Cable cross-section 2.5 square meters. mm

Paved open (regardless of the number of cores) - 30 amperes;

Paved hidden, two single core - 27 amp;

Paved hidden, three single core - 25 amperes;

Paved hidden, four single-core - 25 amperes;

Paved hidden, one two-wire - 25 amperes;

Paved hidden, one two-wire - 21 amp;


Cable cross section 4 square meters. mm

Paved open (regardless of the number of cores) - 41 amperes;

Paved hidden, two single-core - 38 amperes;

Paved hidden, three single-core - 35 amp; Paved hidden, four single core - 30 amp;

Paved hidden, one two-core - 32 amp;

Paved hidden, one two-wire - 27 amp;


Cable cross-section 6 square meters. mm

Paved open (regardless of the number of cores) - 50 amperes;

Paved hidden, two single-core - 46 amperes;

Paved hidden, three single core - 42 amp;

Paved hidden, four single-core - 40 amp;

Paved hidden, one two-core - 40 amp;

Paved hidden, one two-wire - 34 amperes.

If there is a suspicion that operating conditions will contribute to increased heating of the cores, then these standards can be underestimated. But to increase them is undesirable, as this can lead to overheating of the insulation.


1.3 The correct choice of ratings of overcurrent protection devices.

How to ensure fire safety of electrical wiring in an apartment and a houseTypically, this choice is made over the cross section of the cable core. For 1.5 square meters. mm - no more than 16 amperes, for 2.5 sq. mm - no more than 25, for 4 square meters. mm - no more than 40, but for 6 square meters. mm - no more than 50. But nevertheless, it is necessary to take into account the current rating of consumers that are included in the line.After all, consuming current exceeding its own norm, a household appliance can not only fail, but also catch fire, and for a cable and a circuit breaker this will be the normal mode of operation. Therefore, if only one 16-ampere socket is installed in the line, then the machine should not be more than 16 amperes, even if the line cable has a cross section of 2.5 kV. mm

1.4 The right choice of cable routing The basic rule here is that the cable should not directly pass through combustible structures. The most striking example is wooden walls, open wiring on which can only be done on rollers or by placing a metal strip under the cable along its entire length. You can hide the cable in the corrugation or plastic cable channel. Even worse, when the cable is hidden under a wooden paneling - there is a direct danger of a fire. Hidden wiring in wooden houses must be carried out in pipes.


1.5 The device in the room of a real, working fire alarmisations - the measure is by no means superfluous, especially in large wooden houses where fire can spread quickly, and it is not always possible to notice it on time (see - How the fire alarm is arranged and works).


2. Measures to ensure fire safety of electrical wiring at the installation stage

2.1 The most important measure here is the lack of “initiative”. The work should be carried out in full accordance with the project, and in case of doubt or disagreement it is better to consult the designers or the supervisory authorities.

2.2 Cable products used for installation are subject to mandatory certification. Your supplier is required to present a cable certificate upon request. It is better to refrain from using cables of unknown origin and of dubious quality. The same applies to all other electrical products, even those that are not subject to certification.

2.3 All cable conductor connections must be made in the mounting and junction boxes using certified clamps, e.g. PPE. Twisting wires and terminal connections simply on the surface of the wall, ceiling or even under the casing are categorically not allowed.

2.4. Overcurrent protection devices are recommended to be loaded and checked for operability before installation. This is due to the fact that even the most advanced manufacturers allow a certain percentage of factory defects at the outlet, and a defective machine is unlikely to save from excessive current and heating.

2.5 Upon completion of installation, it is necessary to provide access to the junction boxes for subsequent maintenance and contact checks.


3. Measures to ensure fire safety of electrical wiring during operation

3.1 It is necessary to refrain from excessive abuse of tees and extension cords. Extension cables should not be under your feet; furniture and heavy objects must not be placed on them. It must be remembered that the maximum current for any, even double single-phase outlet, is 16 amperes. And this value cannot be exceeded, since the overcurrent protection may not work at the same time, and the outlet can become dangerous.

3.2. It is necessary to systematically check the connection of conductors in junction boxes. This requirement is not always obtained. However, timely detected bad contact help to avoid many problems.

3.3 It is necessary to monitor the state of the clamping contacts of sockets, to change worn out sockets in time, and to prevent the operation of sparkling plug connectors.

3.4 It is necessary not to leave unattended the switched on heating devices - irons, electric heaters, powerful lamps and so on.

3.5 When leaving your home for a long time, it is better to turn off the introductory bag or machine, so that you can be sure that nothing bad will happen in your absence.

Alexander Molokov

We recommend reading:How to choose the right cable section - designer advice

See also at bgv.electricianexp.com:

  • Electrical wiring device in the apartment
  • Which wires and cables are best used in home wiring
  • How to calculate cable for extension cable
  • Internal wiring of a country house
  • The choice of cable cross-section for an apartment, house, cottage

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    Comments:

    # 1 wrote: | [quote]

     
     

    On the one hand, everything seems to be simple. Incorrectly selected cable, machine, overloaded socket, twists, poorly made contacts, poor or damaged insulation can lead to overheating, short circuit, and, consequently, to fire. And on the other hand, in order to foresee, calculate and trace all this - you need to study, study and study again! Conclusion. Contact qualified electricians and you will be happy!

     
    Comments:

    # 2 wrote: ser | [quote]

     
     

    The article is good. All items are painted. Superfluous are lists of cables of various sections and long-term permissible currents to them. This does not carry any useful information and greatly spoils its readability. I agree with everything that is written. Faulty wiring is dangerous not only due to the possibility of electric shock but also the possibility of fire. To avoid a fire due to electricity in the house, a number of requirements must be observed. And if specialists in their field should be engaged in designing and wiring, then it is everyone's duty to know the rules for the safe operation of electrical wiring! By the way, the previous fellow commentator clearly advertises his services here on the site ;-) Or am I wrong?

     
    Comments:

    # 3 wrote: Anatoly | [quote]

     
     

    "Aluminum cable is not allowed for installation." What is the law prohibiting the use of aluminum wires in residential buildings? And why is the requirement of the mandatory installation of residual current devices (RCDs) not addressed? It would be nice to recommend two-stage protection against short-circuit currents, since the advice "It is recommended that the overcurrent protection devices be loaded and checked for operability before installation" can not always be observed. Yes, and during operation, a violation of the protective properties of the protective switching equipment is possible.

     
    Comments:

    # 4 wrote: | [quote]

     
     

    Good afternoon! Before writing about fire safety when laying cables, you should familiarize yourself with GOST R53315-2009 (with changes). It may be that they do in Ukraine (as you advise), but keep in mind that your materials are also read in Russia. Bye Bye.

     
    Comments:

    # 5 wrote: | [quote]

     
     

    Anatolia: 1) This law is called the PUE. And in accordance with it, there should not be aluminum in the newly commissioned electrical installations. Have you seen at least one new apartment with aluminum wiring?

    2) RCD is a wonderful thing. You can, of course, remember her with or without it. But why? After all, RCD protects against leakage currents, and not from smoke and flame. And here we are talking about fire safety, sort of like.

    3) Two-stage protection against short-circuit currents is excellent. And the three-stage is even better. Don't you think that protection should just be, and should be reliable? Quantity does not always go into quality; I assure you.

    Eugene: Hello. I don’t know what is happening in Ukraine, but I would like to know what you saw so seditious in the article. What is contrary to the mentioned GOST, concerning, by the way, markings and properties of wires and cables? And "bye-bye" you, in my opinion, hurried to say explicitly.

     
    Comments:

    # 6 wrote: | [quote]

     
     

    Anatoly,

    And why is the requirement of the mandatory installation of residual current devices (RCDs) not addressed?

    RCD installation is advisory in nature, and not mandatory. And why block 2 or 3 step protection is not a production facility. Best done according to the rules and quality materials.

     
    Comments:

    # 7 wrote: | [quote]

     
     

    I want to ask the author a question - who the article is addressed to. For professionals? - frankly weak, For amateurs? - So they all can’t get into the electrical industry.

    item 1
    They did not remember about RCD very vainly. Its purpose is not only protection against electric shock, but also protection against fire.

    1.2 Section selection ...
    About single-core wires, laid open one at a time - it’s even hard to imagine in a modern dwelling - unless it’s about OHL ... This part could be safely removed, especially since the author recommends using the NYM cable above (and I completely agree with him ) And about his choice just a word - three-core (completely forgotten about grounding) in PVC insulation.

    1.4. Rollers...
    Welcome to the 20s of the XX century. What do you work on rollers with? NYM cable, apparently. Already and praboutwater is not suitable for twisting, and you can’t find a specialist who doesn’t do it himself, but at least sees how it is twisted - no longer find it.

    2.2. Certificates
    Ah, if everyone were honest ... Certificates are on all cable, which is on official sale, regardless of whether it is of high quality or full guano. Not certificates should be watched, but quality! The cable is not the cheaper one, but from a good manufacturer. The same goes for "all other electrical products". By the way, it’s not very clear to me where the supplier will give birth to certificates for those products upon request "that is not subject to certification".  

    2.3. Wire connection
    Twisting is one of the "weakest" places of wiring, and at the same time the most loaded. It is from them that fires often begin.
    All over the world and with us also, all installations (both industrial and domestic) today are done using spring terminals of the WAGO type. They cost no more than PPE, but at times they speed up the exclusion, and create an excellent guaranteed connection for the entire period of operation. A huge plus is the lack of qualification requirements for the installer - I cleaned it by a centimeter, inserted it all the way, and forgot it forever. In this case, you can always add or fold the wire. They can connect up to 8 wires, which is difficult to imagine in a reliable twist, and even more so impossible with the use of PPE.
    By the way, a normal connection will eliminate impossible in a normal living room (not a barn, of course) 3.2.

    P.S. Since the author made a lyrical digression to paragraph 1.5 I would add the purchase of a good powder fire extinguisher (for example OP-4), at least one per floor.

    Good wiring to everyone in the house,
    And do not allow amateurs to electricity.

     
    Comments:

    # 8 wrote: Author | [quote]

     
     

    Yeah. Good.

    Also on points:

    1. About RCD - please explain how it protects us from fire? This is leakage current protection. From etih milliamps what can catch fire? You will not even see them until you feel your own skin.

    1.2 Here you are partly right. About single core - this is background information that is practically irrelevant. And the three-core NYM can be considered three single-core, laid hidden - there will be no mistake.

    1.4 Retro wiring - is this phrase saying anything to you? Not so rare, by the way. And the wire is not a problem (for those who are not poor).

    2.2 Of course, even a certificate does not give a 100% guarantee. You can buy a small batch of cable with a certificate, and then buy a ton of counterfeit goods and poke a certificate in everyone's nose. But still, the certificate is at least something. Price is also only on the seller’s conscience. No one bothers the seller to pull up prices for that same guano. That is why I recommend paying attention to the quality and manufacturer of electrical products. And about certificates for products that are not subject to certification - you, I hope, just read it inattentively. It was about quality. Even non-certified products must be of high quality, right?

    2.3 Vago - a good thing, I do not deny. But PPEs are not bad either. I just cited them as an example - I did not claim that this is the best option available. About the prices of PPE and Vago - here you are bent. Take a look and compare - the difference at times is literal.

    In general, Vago do not suffer any overloads, and it cannot be considered that they do not need maintenance. So in vain did you find the problem 3.2 solved.

    And according to the lyrical digression - yes, a fire extinguisher would not be amiss, I completely agree. And to be able to use it is also mandatory. I had to say a few words about this, I apologize.

    Well, in the end I’ll say that the information provided in this article will not open your eyes to real experts. It is impossible to work professionally with an electrician and not know these common truths. And the rest of the article will help bring knowledge to the system and supplement them.

     
    Comments:

    # 9 wrote: | [quote]

     
     

    1. About RCD:
    Let us turn to the original source (PUE-7), to which the author referred several times, but I doubt that I know him professionally:
    7.1.84. To increase the level of protection against fire during short circuits to grounded parts, when the current value is insufficient to trigger the maximum current protection, at the entrance to the apartment, individual house, etc. RCD installation recommended with operation current up to 300 mA. 7.1.85. For residential buildings, when fulfilling the requirements of clause 7.1.83 of the RCD function according to 7.1.79 and 7.1.84 can be performed by one device with a tripping current of not more than 30 mA. 7.1.86. If the RCD is designed to protect against electric shock and fire or only for protection against fire, then it must disconnect both phase and zero working conductors, overcurrent protection in the zero working conductor is not required.
    I hope the question is cleared.

    1.4. I know about wiring. Recently, I was even told how a rich client wanted to post on roller skates in a bathhouse. Just what does this have to do with the article and the modern home?

    2.3. Here you are right for the price. Take for example SIZ-3 - they can only connect 2 wires with a cross section of 2.5 mm each. The cost is about 1 ruble apiece in bulk. A similar WAGO 773-302 terminal 2x2.5mm2 with paste allows you to connect both copper and aluminum, and copper with aluminum, costs about 3 rubles apiece. Yes, this is a tripling of unit prices. The total estimate for the house will increase ... 300-500 rubles :))
    Statement that "In general, Vago does not tolerate any overload"I didn’t check. I don’t quite understand why? The working maximum current of the 773 series is 25 Amperes, and the 222 series (with lever) is 32 Amperes. If you have installed normal automatic current protection, it is extremely difficult to burn such a connection. Unlike twisting, where the maximum current is not known and depends on a number of parameters - the installer's qualifications (twisting quality), the presence of oxides on the wire surface, humidity (a very big problem with roof leaks and flooding by neighbors), etc. That is why earlier, in the USSR, aluminum twists in apartment wiring were fixed by contact welding. When, before the advent of WAGO, I did copper installations for myself, I soldered all the strands with an acid-free flux.
    With normal installation, paragraph 3.2 is still considered resolved, as in modern home the implementation of paragraph 2.5 is a utopia. If it’s not about wiring again. Well then yes. Wires in rubber insulator with cotton braid, ebonite boxes for outdoor installation, rotary ebonite switches ... This is of course the topic of the 2012 article.

    Z.Y. I was engaged in installation in extreme conditions (temperatures up to +50, in direct sunlight, humidity up to 90%, the number of boxes> 1500 per object, 5 connections per box (3ph + Gr + N). And it is designed for 15-30 years exploitation. But even there is no requirement "systematically check the connection of conductors in junction boxes"... 

     
    Comments:

    # 10 wrote: Author | [quote]

     
     

    1. About RCD. I won’t argue. I slammed the moment - I will take into account.

    2. About retro wiring, and indeed wiring on rollers - why are you attached to it? And in a modern house it has a place to be, I assure you. It depends on what design. What is the problem?

    3. Yes, I am completely for WAGO, I assure you. I even have an article here with relevant content.But this is just an option, like PPE. Vago is more expensive - to some it seems significant, to someone not. Wagos are designed strictly for rated load. Twisting on PPE has a greater margin of safety. But with correctly selected devices of maximum current protection, it practically does not matter, I agree.

    4. The categorical requirement to check the terminal connections was not mentioned. But it’s better, nevertheless, to know what is going on there. Especially if there are VAGOs, the machines did not load, and the wiring was not installed yesterday and is operated in harsh conditions. Still, if the twists are boiled, otherwise it is better to play it safe.

    In general, Sergei, despite the fact that you are clearly a competent person, and I sometimes make mistakes, you are too picky about me and my article.

     
    Comments:

    # 11 wrote: | [quote]

     
     
    Comments:

    # 12 wrote: Author | [quote]

     
     

    As a matter of fact, I gave you only one point - RCD. I can recognize mistakes. And all the rest on your part - not in essence, but only to paint.

     
    Comments:

    # 13 wrote: | [quote]

     
     

    Author,
    The last phrase on your part was clearly superfluous.

     
    Comments:

    # 14 wrote: Author | [quote]

     
     

    Come on? So we get to the arguments of the order "fool himself!"

    But seriously, I got the impression that having found a jamb with an RCD, you enthusiastically began to look for other mistakes in the article, but by and large, they are not.

    No one recommends requiring certificates for uncertified goods. No one imposes antediluvian wires and ebonite switches when there are modern retro-style electrical products (including the notorious casters) that meet the most stringent safety requirements. No one forces you to regularly check the connections of VAGO, and PPE too: they are sure that you have it - and thank God.

    Something like this. But if you want to think that I am an illiterate mediocrity, imposing my amateurish ideas on professionals like you, then as you please. I’m not going to shock diplomas and certificates.

     
    Comments:

    # 15 wrote: Paul | [quote]

     
     

    Author, the installation of an RCD (or a difavtomat) to ensure the fire safety of electrical wiring is a very important point! RCD protects not only from electric shock by a person, but also prevents the occurrence of a fire, which can occur due to current leakage through worn-out insulation of wires and cables and poor-quality contact connections.

     
    Comments:

    # 16 wrote: Sasha_Amateur | [quote]

     
     

    If you don’t know what and what’s better, don’t mess.

     
    Comments:

    # 17 wrote: | [quote]

     
     

    How many sites have never seen disputes about RCDs everywhere))) - Thus, the correct answer to the question is: What is the main difference between RCDs from the difavtomat?
    it sounds like this:
    RCD, unlike a difavtomat, does not protect itself, as well as a circuit and a load from short circuit currents and excess currents associated with overload.

    Isn’t it easier to choose -Difavtomat with the RCD function immediately!

    Oh, I almost forgot - this is not said about the types of RCDs themselves. As much as I know, there are already 3 species. AC-A-B.

     
    Comments:

    # 18 wrote: | [quote]

     
     

    Andrew do not worry, you have everything at the highest level. Professionals understand you perfectly. Some climb to paint, as you correctly noted.

     
    Comments:

    # 19 wrote: | [quote]

     
     

    Andrey, the article is very useful and only a specialist can understand it. Private traders far from electricity who try to make electrical wiring at construction sites, always make gross errors in the selection of cables and protection devices against electric shock and fire. In my opinion, this article is useful only to electricians. Exchange of views on installation issues according to the EMP is in my opinion always available.

     
    Comments:

    # 20 wrote: | [quote]

     
     

    I don’t understand something, or a typo crept into the article: for section 1.5 (and similarly in other sections)
    Paved hidden, one two-wire - 18 amp;

    Paved hidden, one two-core - 15 amp;
    Is everything right here?

     
    Comments:

    # 21 wrote: MaksimovM | [quote]

     
     

    I don’t agree about the aluminum cable. It is permissible for them to mount the wiring. Copper wire is much more expensive than aluminum, so people who cannot afford to mount copper wiring prefer aluminum. Take, for example, a small village or village where the standard of living of people is not very high. Yes, almost everyone in the house or apartment has aluminum wiring.

    In general, it all depends on the quality of the electrical work performed. Correctly calculated and wired aluminum cable wiring, which has reliable protection against overcurrents, will last for more than a dozen years.

    Of course, aluminum contacts are more prone to loss of reliability, but you can choose a reliable contact connection (welding, crimping, reliable terminal blocks) and conduct periodic audits of contact connections (at least once every few years) and then you can be absolutely calm in terms of reliability.

    You can lay a separate line from the distribution panel to each outlet of the room, then the problem of the reliability of intermediate contact connections disappears. Such a scheme when using aluminum wire can be implemented for a relatively small amount. Therefore, if the budget provided for replacing the wiring is small, many will prefer a circuit with separate lines of aluminum wire to each outlet than a circuit with copper wire, but using intermediate junction boxes, since the latter circuit is less reliable.

    I recently checked the contact connections of aluminum wires on the screw terminals of the electrical wiring, which was installed 4 years ago, so none of the contacts were weakened. And this despite the fact that these circuits in the cold season under a decent load, since in addition to conventional electrical appliances, the electrical wiring fed several electrical convectors. Another example is the relay protection and control circuits of substations 50-70 years old, which were mounted with an aluminum cable, and contact connections were made using screw terminal blocks. After such a long time, these contact compounds did not deteriorate. When dismantling the old relays, the terminal blocks had to bite off the wires, since it was very problematic to unscrew them.

     
    Comments:

    # 22 wrote: Anatoly | [quote]

     
     

    The given values ​​of the rated currents do not correspond to the actual values ​​of the rated cable currents. For example, for a three-core copper cable with a cross section of 2.5 mm square, one core of which serves as a protective conductor, from the VVG series, according to GOST, the rated rated current when laying it in the ground (although these cables and not intended for laying in the ground) is 36 amperes, according to the PUE - 44 amperes, that is, the GOST takes into account the cable stock for a nominal current of 8 amperes. When laying outdoors, the original VVG cables with additional PET insulation on top of all cores under a common sheath and an operating temperature of + 80 degrees Celsius with a cross section of 2.5 millimeters square, according to the cable manufacturer, they have a nominal current of 33 amperes. Cable - wires from the VVG series with polyvinyl chloride insulation lived in a common sheath made of vinyl hose compound and without additional insulation, on top of all cores have a rated current when laid in the open air, and according to the cable manufacturer and according to the PUE and GOST 27 amperes and the maximum operating temperature a round of + 70 degrees Celsius. Cable routing and cable - wires with a protective sheath are not provided for PUE in grooves under the plaster layer or in corrugation and PVC pipes. However, in practice such cable routing and cable - wires are carried out. But here is the rated current cable - wires in the corrugation,given the PUE for the corrugation of the cable - wire 0.3 - 0.5, of course, you can take the nominal current of the copper cable - wires from the VVG series with a cross section of 2.5 mm square equal to 21 amperes, as for a three-wire wire when laying it in the pipe, however, the cable sheath is real - the wires interfere with its cooling in the corrugation and the exact value of the rated current of the cable - wire remains unknown. When directly laying the cable - wires in the furrows under the plaster, the exact rated current of the cable - wire also remains However, the estimated thermotechnical calculation of the rated current of the cable - wires laid, for example, in the grooves in aerated concrete under a layer of gypsum plaster shows that the rated current of the cable - wires in this case is not more than 10 amperes, taking into account the low thermal conductivity and heat capacity of the aerated concrete. the line protection switch must have a rated current of not more than 6 amperes, and usually a circuit breaker with a rated current of 16 amperes is usually installed, at best. about the current cable - wire is that if the thermal energy released by the cable - wire, when the current flows through it, there will be more thermal energy that can be removed from the cable - wire, the cable - wire laying medium, then the cable - wire when it heating will not be able to reach the state of thermal equilibrium and will, due to excess thermal energy not diverted from the cable - wire, due to the low thermal conductivity of the cable - wire laying medium, heat up to unlimited temperature until the cable breaks down and whether it ignites, this is one of the main causes of fires due to electrical wiring failures. But the exact rated current of the cable-wire is unknown when it is laid in furrows under a layer of plaster. Therefore, it is much better to carry out apartment wiring with single-core single copper wires in single insulation in corrugation with a corrugation factor of 0.3 - 0.5 and a guaranteed rated current for a copper wire with a cross section of 2.5 mm square 27 amperes, according to the PUE. Moreover, the cost of such wiring is 13% cheaper les than running cable - wire in the furrows under a layer of plaster and its capacity is 30% higher and provided garantiroaannaya defense lines against overloads their current, attached to them-breakers with a rated current of 16 amperes.