Is your house safe from Electrical Fire and Shock?

Why electrical safety?

One can hear the news of death due to electrocution and fire almost every day. One of the prime reasons for the fire incident that is talked about immediately is ‘short circuit’. Usually, the memory is short, and one forgets within a few days of the happening but indeed provoking thought for a short period in your mind “Is my house safe from electric fire and electrocution?”

It is our best friend as long as we handle it properly but may be dangerous otherwise to life and property. Since the flow of electric current is not visible to naked eyes, it is difficult to visualize its fatality and what measures ensure safety. This post is with the intentions to make a common man understand how to ensure electrical safety in his house in an easy to understand language.

What you should know about Electric safety?

The only principle involved is that there is no chance for electric current to leak out from its intended path. It leaks out either through ‘direct’ or ‘indirect’ contact.

Direct Contact

The current not to leak directly is by ensuring the insulation of live parts, adding barriers and having enclosure so that no one comes in contact with the live wire. The items used in anyone has to care in his house for providing safety towards these items are

Cables/wires

The wire consists of Cu conductor in accordance with IS 8130 (avoid aluminum) and insulation. There is no protective sheathing use in single-core stranded cables for the house wiring. The standard specification is covered under IS 694 (with category C1 for fire retardant and C2 for Fire Retardant and low smoke). The copper conductor is multi-stranded in accordance with clause 5 of IS 8130-1984. The wires 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 are determined in accordance with IS 3961 (Part V)-1968 as under:

As a general principle, all light/fan circuit is wired with 1.5 sq.mm. and power plugs 6/16A with 4 sq.mm. cable.  In fact, there are many manufacturers claiming their manufacturing as per IS standard but with the price varying very largely. You will find many marketing strategies adopted by leading brands to attract customer like

1. “Polycab cables save energy up to 25%”. No documentary evidence is available to support this claim on company website except stating use of Advance Triguard Technology;
2.  “Havell’s cable which does not catch fire”. This because of Fire retardant property in which fire does not propagate in accordance with Is 694 C1 category. The best way to check is to just put the wire on flame and if the cable does not burn means it is Fire retardant. Many more brands qualify for this category.
3. Low smoke and Halogen-free wire are not much of an advantage in your house when wiring is concealed in conduit since the starvation of oxygen will result in the fire either not to initiate or extinguish immediately.
4. ROH i.e. Restriction of Hazard Substance in Electrical and Electronic Equipment such as Hg, Pb, etc. When it is mandatory, all cable manufacturer to comply with this.
5. Temperature Rating and Index are other parameters but not much relevant for house wiring.
6. Anti-termite and Anti-rodent are stated in manufacturers claim but no mention of the standard to which it is tested. In concealed wiring with sealing at the end is not relevant for house wiring.

The color code generally followed are RED, BLUE, YELLOW for phase, BLACK for neutral and GREEN for earth wire

One can examine the 1.5 sq.mm. 90-meter roll price and  wire specification by the leading manufactured marketed at Amazone are as under:

Switch and Socket

Switch and sockets are used for plugging/unplugging appliances with the provision of switching ON and OFF function making it vulnerable to failure, insulation failure, insulation failure. The socket and switches are manufactured to Indian Standard IS 3854:1997. One of the test one can perform at home that it should not burn when ignited. While selecting, always go for sockets with shutter.  Check the photo of  safety shutter and price at amazon

As regard plug read https://www.bijlibachao.com/general-tips/why-use-3-pin-plugs-for-electrical-safety.html

Steel or GI Box

Steel or GI Box is used to house the switch and socket panel and in accordance with IS 5133. Never use box other than steel or GI box to look for the advantage that if the wire comes out, it will not cause MCB to trip.

Conduit

Always prefer concealed wiring, using the conduit in accordance with Indian Standard

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

For reason, if the flexible conduit is required for wiring in the open, always use metallic flexible conduit.

Cable jointing

Cable jointing should always be avoided. There is standard practice developed in Indian electrician to twist the strands and using insulated tape to insulate. Such a practice should be avoided. The latest technique that is now getting popular is wire jointing terminals, heat shrinkable sleeve and heat shrinkable sleeve with solder. See image and price at

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

Indirect Contact

Even with all the measures ensure to prevent direct contact, a person may come in contact with the live wire accidentally or through leaking current. The protection is ensured by

Fuse

The fuse, when selected of correct rating, is the most reliable mode of protection towards short and overload current. The main disadvantage is that if blown, it takes time to change with another fuse. For this reason, MCB was developed, but are preferred at the distribution board. After the energy meter, one should always provide fuse or cartridge fuse and fuse wire selected of the right size or use standard cartridge. See image of cartridge fuse

MCB

MCB is a very popular and no household protection system can be imagined without the use of MCB or called Miniature Circuit Breaker. MCB is manufactured in accordance with IS 13032:1991. MCB is distribution and sub-distribution board. The standard sizes of MCB for load vs MCB rating are 1-4A/6A, 6A/10A, 16A/20A, 20A/25A, 25A/32A, 32A/40A etc. Type B is recommended for resistive loads having least inrush current and Type C for Air Conditioner having a high level of inrush current due to inductive load. See image of various makes of 10 A MCB at amazon

ABB is pack of four and Schineider is pack of two.

RCCB

RCCB is the most important protective device to protect your house from fire, damage to appliance and electrocution. Believe it, RCCB protects your house from any possibility of initiation of fire.  See image of RCCB of 63 A 100 mA sensitivity

Read more about RCCB on https://www.bijlibachao.com/general-tips/why-is-rccb-necessary-for-your-house-rcd-electric-shock-residual-current-detectors-rccb-circuit-breaker.html

Earthing

The word ‘earthing’ is used in UK whereas ‘grounding’ in US but meaning the same. Earthing has a significance in electrical engineering to the fact that earth has a very high capacitance of .0007 F, a very high value assuming it is infinity, and not to cause any potential change (V=Q/C) when gaining or losing even enormous charge during lightning, fault current, etc. It is, therefore, convenient to accept earth body possessing equipotential, and thus, accepting as a reference potential. Every electrical appliance body is connected to the earth and the reason for the word ‘earthing’ (or grounding) to find relevance. Earthing provides a path for the fault current to flow through the earth and helping the protection relay to sense the high current and trip the circuit. Read more on Earthing and Electrical Protection and Fire Safety on

1. https://www.railelectrica.com/electrical-protection-fire-and-safety/earthing-a-must-for-every-one-to-understand-its-importance-for-electrical-safety/
2. https://www.railelectrica.com/electrical-protection-fire-and-safety/electrical-protection-fire-and-safety/

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