These days almost everybody uses electricity in their houses and work places. So having at least a basic understanding of domestic electric circuits would help you immensely. I thought to help you achieve that goal through this post. Okay, it’s about most common electrical parts and components of house wiring circuits.
It is important to have a basic knowledge of these parts to make your life easier when it comes to using electricity the hassle-free way.
In countries such as Sri Lanka, India, Nigeria and many others have 230v basic electricity power supply to consumers from the national electricity grid which is an alternating current (AC) with a 50Hz frequency. However, the Voltage and Frequency can be different for other countries, for example United States has 120v electric power supply with a 60Hz frequency.
The electricity supply is given by a service cable consisting two wires known as Live wire (L) and Neutral wire (N) according to the Voltage & Frequency regulations of your country. Now let’s focus on a few electrical parts often you can see in your home.
Basic Household Electrical Parts & Materials
1. Electric Meter
First in the list of common electrical parts you see everyday is the Electric meter. It is used by the national electricity grid to measure the units of electrical energy used in your household circuits. Yeah, that’s how they find the amount you need to pay for your electricity bill per month.
Kilowatt hour (kWh) is an energy unit.
Suppose you have a 1000W electrical appliance in your house and you have to use this appliance for one hour everyday. Then the electrical energy consumed is one kilowatt-hour per day. Electric Meter calculate this consumed electric energy through the circular disc fixed in it.
When you use electricity, this circular disc starts to rotate which records the number of electrical energy units used by you. If you look closer inside the meter, you can see there are digits moving at the same time when the circular disc rotates.
Electricity grid company uses that meter readings to create your monthly electricity bill every 30 days or so.
1 kWh = Amount of Watt x Number of hours used / 1000
1 Unit = 1kWh
A fuse is an electrical part which you can’t see as it’s always inside a plug or an electrical device such as TV.
Basically fuses are used to protect electrical appliances, parts and electronic components from potential damage due to a high current – Ampere – flowing in the circuit.
This electrical part is a small length thin wire created using lead and tin alloy. These days fuse wire is commonly seen in a glass tube for easy use. There are different fuse wires with the ability to conduct certain maximum currents such as 3A, 5A, 13A and 15A.
Yes, that’s for the domestic electrical circuits, fuses for the commercial systems can go as high as 300,000A. When designing the circuit diagram the circuit designers use various symbols. Do you know which symbol represents a fuse?
It’s this symbol ⏛ where you strike a small rectangle box that represent the electrical part protecting your electrical devices – Fuse!
Curious on how exactly a simple wire do the protection duty without the muscles?
When electrical current flows through the circuit exceeding the rated ampere value of the fuse, the thin wire melts down (fuses) thanks to heating effect of electric current and in return makes the closed-circuit an open-circuit. As you already guessed, open-circuits never flow electrical current, hence the current flow is cut down suddenly while protecting the appliance and other electrical parts & components.
In other words, fuse is kind of a superhero which saves the day by sacrificing itself for the greater good.
This is why when the fuse goes down, you need to replace same value and same size of fuse. This is also a safety rule. Want to know more electrical safety rules?
When a fuse goes down, it’s gone forever. Since replacing fuses seem annoying, a new electrical part was created to avoid such complications.
This component is a miniature circuit breaker and it looks like a switch consisting various ampere values. Circuit breakers function similar to fuses. In the event of an exceeding current flow than the rated ampere value, the switch opens and stops the current, instead of melting anything or dying forever. The circuit can be connected again by closing the switch.
3. Distribution Box
Distribution box is another easy to notice electrical part in your home. It consists 3 more electrical parts, namely,
- Main Switch (MCCB – Moulded Case Circuit Breaker)
- Trip Switch (RCCB – Residual Current Circuit Breaker)
- Circuit Breakers (CBs )
As the name implies, Distribution Box simply distributes the electric supply to sections of the house. These sections contain light circuits [Light Switches + Light Bulbs], fan circuits [Fan Regulator + Fan] and plug socket circuits.
In each of these circuits the Live Wire is connected to a circuit breaker which will be explained in a moment.
4. Main Switch (MCCB)
You know every house or commercial building has a distribution box which is where the Main Switch is located. It’s the first electrical part receiving the electricity from the electric meter inside your house. Therefore the Main Switch is the responsible part to take down the electricity throughout the house as required.
Often useful while upgrading house wiring and when thundering & lightning to disconnect the supply.
There are 2 wires inside the cable coming from the electric meter namely Live Wire and Neutral Wire. These 2 wires are then connected to the Main Switch. While the main switch is OFF the electric supply is stopped by disconnecting the two wires.
Yes, you read it right.
Remember, current flows only when the circuit is closed, hence the current flows specifically when the Main Switch is ON. That’s why you need to OFF the Main Switch to disconnect the power. Quite the other way around than the usual “switch on”. Right?
5. Trip Switch (RCCB)
Remember the fuse I explained earlier? Just like a fuse, protecting people and electrical appliances is the primary goal of the Trip Switch, an electric switch designed to interrupt a circuit suddenly & automatically.
However, it’s not a fuse, but a type of circuit breaker. This electrical part’s common name is Trip Switch while the technical term is RCCB – Residual Current Circuit Breaker. Trip Switch is there to help you multiple times compared to a fuse.
Electric current coming from the Main Switch connects to the Trip Switch via Live & Neutral Wires.
If there is a fault in any of the circuits in the house this switch opens (Trip) automatically and disconnects the power supply. For example, when someone gets electrocuted or when your house become a target of a lightning attack. Since the Trip Switch is so useful, it comes with a Test Button letting you check if it works as expected.
Working Principle of RCCB
Residual Current Circuit Breakers work by comparing the current entering the appliance via the live wire with the current leaving the appliance through the neutral wire. This difference in electrical current is called the residual current. RCCB Tripping current commonly 30mA (0.03A) or 100mA (0.1A), depending on the country it will change.
RCCB consists of,
- Primary coil
- Secondary coil
- Trip coil
Always Primary coil and Secondary coil will sense the load current (IL and IN). When the circuit is OK the IL=IN, then trip coil will not get any current (IL-IN=0A) to energize the trip coil.
When the circuit Not OK the IL>IN, it means the trip coil will get some amount of current (IL-IN=3A). If IL-IN exceeding the RCCB tripping current, Trip coil energized and RCCB immediately trip.
It can happen due to a fault in the circuit Or when earth leakage current exceeds the value of tripping current of the RCCB.
6. Wall Switches
No wonder you have switched the switches thousands of times. Wall Switches are among the top consumed electrical parts list in any place that uses electricity.
Switches are used in light circuits and plug socket circuits to connect or disconnect the circuit according to the will of the individual.
There are different types of wall switches such as Push Button, Press Button, Toggle and Rocker while the latter is the universal light switch used on most houses these days. Then there are single, double, triple, quadruple as well as quintuple wall switches.
Electricians can attach multiple lights to a single switch as long as the current rating of the switch is not exceeded, for example all outdoor lights can be attached to a single switch letting you light up them at once easily.
7. Plug Sockets
Plug sockets are used to get electric supply for appliances like computers, electrical heaters, televisions, refrigerators and whatever electrical device you’ve been using.
Do you know that Plug Base is another name used to refer Plug Sockets? if you didn’t, now you know!
There are plug sockets to get 5A, 13A or 15A current. Similar to wall switches, there are different types of Plug Sockets based on pin type such as two-pin plugs and three-pin plugs where the 3rd pin is for Earth Wire. To get these connections, electricians use two core wires and three core wires.
Plug Sockets come with a switch for extra protection, so you don’t get electrocuted or harm your appliances while plugging. For safety, you need to OFF the switch before plugging any plugs.
8. Electrical Wires & Cables
Electrical wires are used to transport electric current, be that from electric meter to distribution box to power outlets (Plug sockets), all things get the supply through various electrical wires.
There are 3 types of electrical wires,
- Live Wire
- Neutral Wire
- Earth Wire
Each of the above wires contain different color codes depending on the country and in here Sri Lanka we have following wire color codes.
Wires with Red or Brown colors are used for live connections, so those are the Live Wires. Then the wires with Blue or Black colors are used for neutral connections, so they are the Neutral Wires. If you see a Green or Yellow-Green wire, remember they are used for earth connections, which means those are the Earth Wires.
Household circuits are designed by using various types of wires as explained above. Electrical cable is formed when all these 3 wires or at least the crucial 2 [Live & Neutral] wires are insulated with rubber or plastic cover. Here are more important details about electrical wires.
|Wire Code||Area of cross section of the wire (mm2)||Rated Maximum Current (A)||Colors||Use Cases|
|1/1.13||1.0mm2||11A||Red Or Black||– Lamp Circuits
– 5A Plug Base Circuits
|7/0.50||1.5mm2||15A||Red Or Black||– 15A Plug Base Circuits|
|7/0.85||4mm2||24A||Red Or Black||– Power cable from Electric Pole → Electric Meter → Distribution Box|
|7/1.04||6mm2||31A||Red Or Black|
9. Two Way Switches
Two way switches are the last electrical part explained in this article. It’s a bit different than the normal wall switches in terms of how it operates.
These switches are used to operate a light from two different places. Normal wall switches only has 2 connections, while Two Way switches got 3 connections.
Couple of ways Two Way switches are used,
- When you need to ON and OFF a light bulb in a staircase from top as well as bottom.
- To ON and OFF a light bulb outside your door, when you go out at night.
For example, in the 2nd instance, you ON the switch while you inside the house and then you lock the door once outside. Now you want to OFF the switch, how do you do that? Talk to Barry Allen to get the powers of going through matter? Nope!
You setup a Two Way switch outside the house and you OFF it there.
Wrapping Up The Common House Electric Circuit
Okay, this section wraps up how all the electrical parts explained above is used in the common house electric circuit.
It all starts with the place where the electricity is generated. Then the electricity is transmitted through high power service cables. In Sri Lanka, first level is 66,000 voltage, then it steps down to 33,000 voltage and then again to 11,000 voltage.
From the 11K voltage, Three-phase starts which is what you usually see in the road. It contains 3 Live Wires and 1 Neutral Wire. Three-phase is the reason why your house can face a power cut while some of the houses in your block or area don’t.
Main wire coming from the electric pole first is connected to the electric meter in your house. From the electric meter the Main Wire is connected to the Main Switch and then through the Trip Switch to the Circuit Breakers in the Distribution Box. Circuits to various sections of the house starts from the Circuit Breakers.
Here’s a common house wiring circuit.
Did you enjoy this article? It took me a while to create all the images such as the above house wiring circuit created with the electrical parts explained above. So, I’ll be glad to have you share this article or images with your friends and students.
Mohammed Ebrahim says
Hey you.. the one who typed this article … you having a great way of explaining things in simple… and good humour tooo ” BARRY ALLEN” …. huh..??? Great work sir
Shyam Chathuranga says
Thank you for the sweet comment Ebrahim. I’m glad you enjoyed the article while learning a few things. Let others have that experience by sharing the article with your friends. Good luck!
right you are
Gehan Wijesinghe says
Hi Shayam, very plainly written but very detailed write up and I congratulate for your efforts.
I too am an electrical enthusiast ( thought I am a financial guy). Recently we moved into a new house, fairly large and luxurios type with so many light fittings and socket outlets.
The house has been wired with a single phase connection ( and I think ampearage wise this would be more than sufficient for us). But in the pantry hre are around 8 socket outlets both 13A/15A and 5A. And I found out that all of them are being supplied through one 6A MCB. ( MCB is a 6A, but I am yet to open the box and check the cable size).
We have hooked the fridge, mircowave oven, rice cookers and a electric kettle to this loop. However I must tell that apart from the fridge which is mostly on, all others are used at individual times are never together. The worst could be the fridge & micro or fridge & kettle, at separate times.
But whenever I plug on the kettle ( 2200W) the mcb trips. Even when I unplug all other equipment mentioned above and switch on the kettle, the mcb trips after about a minute. But the MCB does not show any rising in housing temperature, like in most cases.
According to the W=IxV, I see that this kettle would draw about 9A and even the normal cable allows around 11A max, and is a bit unusual, according to my very limited knowledge.
My problem is that this house is sturdily built and I could not see any place or any way where I could replace this pantry circuit cable with a broader cable. I know replacing MCB with a higher rating is asking for trouble and not the solution.
Do you have any advice. I am trying to locate the electrical contractor who did this house but so far failed in my attempts.
Please give me some advice.
Incidentally, I have solved my immediate problem by plugging the kettle into a socket in another room, but it is not the thing to do as we have paid a hefty amount and we need to plug kitchen utensils in the kitchen outlets.
I appreciate you cannot help me with this situation, but I need your comment on the ampere carrying capacity of the cables at least. I suspect this circuit is wired with 1.044 cable.
Shyam Chathuranga says
Thank you for commenting at SmartSciencePro and your feedback about the article.
First, What you figured out as the solution is correct. Changing the CB to high amperage will fix the problem.
Second, When the refrigerator’s compressor starts, it takes a high amount of current for a small time and when the CB’s limit surpass, it automatically trips. This must be why it happens when both Refrigerator & Kettle is plugged in.
Third, you could further test that by only attaching Refrigerator alone.
Hope this helps.
Harsha Kotuwegedara says
Thank you very much for this article. It helped for my studies and glad we have this kind of sites in our country.
Shyam Chathuranga says
Thank you for the comment Harsha. I’m glad Smart Science Pro was able to help you today. Support the SSP by sharing the article with your friends on social sites. 🙂
Muy interesante, Vale
KASUBI JOEL says
Thank you for posting this information. My name is KASUBI JOEL, an engineering student in Busitema university ( UGANDA). I have found this information important and self-explanatory
I really enjoy this article and it’s very educative. Please i want to know few things more. where is the right place to run earth wire into the ground? From meter or circuit breakers? Another question is, Can you please list out the sizes of wires to use for home appliance? Eg, Freezer, A.C, Electric cooker, fan, bulb etc.
Jeremiah THOMAS says
Thank You very much . My Name is Jeremiah THOMAS Iam a Electrical technology student from a technical school here in PAPUA NEW GUINEA This information was helpful ,i completed my electrical technology project with the help of the information provided.
Very good, easy to understand
Joseph Rindap says
Hello you really try may God bless you with more knowledge because is not everybody that can share it out like this
Shyam Chathuranga says
Thanks for the appreciation Joseph. Please stick with SmartSciencePro and share the article with anybody you feel it is useful. 🙂
Thank you.i learned the basics finally ,of what our electricity consists of in regards to home wiring.i still have questions.such as::
When removing a hanging chandelier,I get confused when I need to undo the “house supply wires” from the socket. I mean there are wires connected to the lite fixture but what are the house supply wires? Will I be messing up other elect. Devices by disconnecting them?
Im a new electrical student (retiree) I’m always seeking electrical information on the internet for clarification of troubled areas in class. This is the best I read so far
Shyam Chathuranga says
Thank you for sharing your thoughts Jessie. I’m glad SmartSciencePro was able to help you 🙂
Am glad I stumbled over this article. Thanks a lot.
My question is: does the two way switch really on each other to work.
I think not all switches can be use as two way Control switch
rick s says
Thank you and God bless you for sharing knowledge to humanity. Questions. 1. Meter is 3/9 @ 220V, can I use a 60A MCB or do I need to match the meter’s amp like a 9A breaker? 2. Can a aluminum wire be used from pole to MCB then out as copper wire? 3. Is RCB breaker like a regular breaker? 4. My meter doesn’t have an Earth connection, so should I just make my own Earth connection on the Distribution Box? 5. This last one is very confusing. All CB’s have 2 holes, 1 for Line and 1 for Neutral, so in your diagram, we don’t have to insert the Neutral wire into the breaker?
Suryansh Goyal says