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Is your house safe from Electrical Fire and Shock?

By on November 9, 2019 with 8 Comments  

“With great power comes great responsibility.” I know this line sounds a bit cheesy, and I am sure you would have heard it umpteen number of times. But then when we are talking about “power” or “electricity”, it does make a lot of sense. Quite frequently we come across news of someone dying due to electrical fire or electrocution. One of the primary reasons cited for the same is “short circuit”. Most people brush it off as a one-off incident and do not think if their own house is safe from electric fire and electrocution or not. But electrical safety is a great responsibility that we have for being a consumer of electricity.

Electricity is our best friend if we handle it properly, but otherwise, it can be quite dangerous. It is difficult for humans to visualize the flow of electricity. And that is why we find it very difficult to ascertain the amount of hurt it can cause. We have written this post intending to make a common man understand some simple steps to ensure electrical safety in your house.

Things that you should know about Electric Safety

The main objective behind electrical safety is to make sure that the current does not leak out from its intended path. There are two ways in which the current can leak out: Direct Contact or Indirect Contact. Let’s look at how to block these two:

Direct Contact

Any contact with live wire can be hazardous. It is essential to provide proper insulation to live parts and making sure that these are enclosed properly. A few items that you need to take care of while setting up your house are:

Cables/wires

When looking for Cables, you should make sure that you buy a cable that is made out of copper and complies with IS 8130 for insulation. Please avoid wires made out of aluminum. There are two types of wires available: Single-Core and Multi-Core, as shown in the image below.

Single Core And Multi Core Wires

Single-Core And Multi-Core Wires

Usually, single-core stranded wires are the ones used for house wiring. As shown in the image above, there is no protective sheathing (or black covering in the image above) available in single core stranded wires. But the copper conductor is still covered with PVC insulation. There is an Indian Standard: IS 694 for the PVC insulation. A PVC insulation is of category C1 if it is fire retardant and C2 if it is fire retardant and has low smoke. Do check for these categories while buying a cable.

The copper conductor inside a wire should be multi-stranded as per clause 5 of IS 8130 – 1984 (as shown in the image below). This is done to provide flexibility.

Single and Multi Stranded Wires

Single and Multi Stranded Wires

The wires dimensions are defined in terms of sq.mm. of cross-section and sizing is determined based on current-carrying capacity. For house wiring, the sizing is generally in the range of 1 to 6 sq.mm with current-carrying capacity  determined in accordance with IS 3961 (Part V)-1968 as under:

 

Size (in sq.mm.)Current carrying capacity in Amp.DC Resistance in ohms/km at 20 degreeOuter diameter including insulation in mm
11219.502.44
1.51613.502.66
2.5227.983.27
4294.953.99
6373.34.52

As a general principle, all light/fan circuits are wired with 1.5 sq.mm. and power plugs 6/16A with 4 sq.mm. cable. When a cable or wire is installed, make sure that your electrician follows a color code: RED, BLUE, YELLOW for phase, BLACK for neutral and GREEN for earth wire.

Some brands market that their cables/wires can save electricity. However, Power loss in a cable depends on the resistance of the wire. And the resistance of a wire depends on the cross-sectional area of the wire. So ideally it should be the same for all copper wires with same cross section. So we at Bijli Bachao are not convinced with the message.

Here are some good wires (1.5 sq mm) available on Amazon:

Switch and Socket

Switch or Socket is another important component that you need to take care of when you take up an electricity safety project. Being switched on and off regularly, they are vulnerable to failure, especially insulation failure. The sockets and switches in India are manufactured as per Indian Standard IS 3854:1997, so when you buy one, make sure that this standard is mentioned on the box. One of the tests to make sure it follows the standards is to try to ignite it and see to it that it does not burn.

While selecting sockets, make sure that you go for sockets with a shutter so that kids to not accidentally put their fingers inside it.

Here are some good sockets on Amazon:

You can further read on some tips for plug safety on this link: Why Use 3-pin plugs for electrical safety?

Box to house Switch and Socket Panel

Indian Standards have section IS 5133 which is meant to provide specifications for the box to house switch and socket panel. Please make sure that you buy a Steel or GI Electrical box.

GI-Box

Someone may advise you using a different type of  Box, but please remember, for safety, it is better to use Steel/GI Box since in case of a fault it will result earthing and tripping of MCB.

Conduit

Leaving wires in the open is always not desirable, and it is better to use conduit concealed wiring,  not only for better aesthetic but for safety as well.  You will need a conduit to do the same. Always go for a conduit which is in accordance with Indian Standards:

Non-Metallic: Rigid: IS 2509-1974 and 3419-1989; Flexible: IS 9537 (Part 5) 2000

If a flexible conduit is required for wiring in the open, always use metallic flexible conduit.

Cable joints

A standard practice that is typical in India, to join cables, is to twist the strands and insulate them with insulation tape. However, that practice is prone to risks and hazards. These days you can get cable connectors in the market that can be used to join cables safely. You can also use a heat-shrinkable sleeve or a heat-shrinkable sleeve with solder to provide extra insulation to make it safe. Some of those products on Amazon are listed below:

The purpose of all these products is to ensure that no one comes in direct contact with electricity.

Indirect Contact

Even after taking all the measures, a person may come in contact with a live wire accidentally. It can happen through a current leakage somewhere in the system. To protect such inadvertent contacts, you should look at installing these in your house:

Fuse

A fuse is meant to provide protection from short and overload current. It is the best and most reliable mode of protection if you install one with the right rating (based on the connected appliance and their current usage). However, a fuse that is blown needs replacement, and this can cause inconvenience to some people. And to avoid that inconvenience, one can use an MCB (Miniature Circuit Board). But please note that MCB is good if used at the distribution board. After the energy meter, it is always good to use a fuse or cartridge fuse of the right ratings instead of MCB because the reliability of protection is best achieved by a fuse. Here is an example of cartridge fuse available on Amazon:

MCB

MCB or Miniature Circuit Breaker is another good tool to protect from short and overload current. MCBs are very popular these days, and it is difficult to imagine a house without it. MCBs are manufactured in accordance with IS 13032:1991. MCBs are provided at the distribution and sub-distribution board. The standard sizes of MCB for load vs rating are 1-4A/6A, 6A/10A, 16A/20A, 20A/25A, 25A/32A, 32A/40A etc. You should use the help of an electrician to find the right size as per your requirements. They are available in two variants: Type B and Type C. If you have an appliance with a motor and you want to use MCB for it, then you should use Type C variant. For all other resistive loads (like lights, Fans, TV, etc) you should use Type B. Here are some 10 Amp MCBs available on Amazon:

ABB is a pack of four and Schneider is a pack of two.

RCCB

RCCB or Residual Current Circuit Breaker is one of the best protection for your house from electric shocks. Electric shock can be hazardous and can also lead to loss of life. Thus it is crucial to have an RCCB in a house. RCCB cuts of the electricity supply whenever it detects current leakage beyond a certain point. While choosing RCCB, the manufacturers recommend for 30 mA sensitivity one shall select the same. Such sensitivity irks when there are spurious tripping without any obvious fault. Most of the user gets the RCCB bypassed to avoid this. In case you are unable to take pain in identifying the defect when a circuit trips due to 30 mA sensitivity it is better to go for 60 mA instead of bypassing or not providing at all. Because of this, we usually suggest going for an RCCB with a sensitivity of 60 mA. Here are some RCCBs on Amazon with 63Amp rating and 100 mA sensitivity:

You can read more about RCCB on this link:  Why is RCCB necessary for your house?

Earthing

Earthing (also known as grounding in the US) is an essential aspect of electrical wiring in a house. In layman’s terms, Earthing acts as a “drainage” for leaking current. All appliances should have proper earthing. It is done by connecting a wire to the metallic portion of the device, and that wire goes in the top (thick) pin of a three-pin plug. Every house should be wired in such a way that there is earth wire running throughout the house. The earth wire should collect leakage current from all the house and “ground” it or move it to earth (literally). It is essential to have proper earthing in your house. Make sure you get it done properly when you are setting up your house. Avoid renting a house which does not have good earthing.

Here are a few more articles that you can read on Earthing, Electrical Protection and Fire Safety:

‘EARTHING’, a must for every one to understand its importance for Electrical Safety

Electrical Protection, Fire and Safety

About the Author:
Mr Mahesh Kumar Jain is an Alumnus of the University of Roorkee (IIT Roorkee) with a degree in Electrical Engineering who has spent 36 years serving the Indian Railways. He retired from Indian Railways as a Director of IREEN (Indian Railways Institute of Electrical Engineering) and has also served as Principal Chief Electrical Engineer at many Railways. He has performed the responsibility of working as Electrical Inspector to Govt. of India. Mr Mahesh Kumar Jain is having passion for electrical safety, fire, reliability, electrical energy consumption/conservation, electrical appliances and has always been an inspirational force behind this website in assisting in these areas.  He currently serves as a consultant at Nippon Koi Consortium. .

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