How to Prevent an Overload at Homes

Compliance with the appropriate and applicable national electrical code is the key. For example, in the UK it would be British Standard 7671.

Because <...in many parts of the world, electrical codes are either non existent or obsolete, and generally not enforced...> there is generally no <...means to prevent overload in...home...>.

There is no <...Unfortunately...> in the equation.

You should know the size of each circuit and what amperage every appliance requires...Use an amp probe to measure actual current draw on each circuit with everything on...

Ahem - er - that's for the installer to do, not the user. It is the installer's responsibility to make sure that the installation is safe for the user.

Well aren't you the trusting soul....what about plug-in's?

Don't you study the movement of electrons through conductors in EE?

As PWSlack said, electrical codes, obsolete or not, are a useful guide.

Not knowing where you are located precludes any authoritative answers from coming forward.

To answer your question, yes http://tccelectricalcontent.com/prevent-circuit-overload/ would be a good guide for the uninitiated.

If you try to push too much water through a pipe resistance builds up quickly. Resistance causes heat somewhere in the system. Same is true with electrical conductors. Try to push too many electrons through them and they get very hot. That's how incandescent light bulbs work.

To the original poster:

We also have trolls who add nothing to the forum, but find a certain joy in causing problems for legitimate posters. Anonymous Poster #2 is a perfect example of that.

In the article that you referred to, http://tccelectricalcontent.com/prevent-circuit-overload/. Item 4 "Non-convential sizing" is incorrect in the example they gave. Protecting #12 conductors (rated for 20A) with a 15A breaker would not be a problem.

What I think they meant to say is that using a 30A breaker in this circuit would be a definite hazard! What they are attempting to say is the circuit protection ( fuse or breaker) must be sized to the capacity of the conductors in the circuit, and the conductors be sized to the expected load on the circuit.

We have similar issues in PR, USVI is worse. In my place the 110 devices are on one phase, the other is used for 220 only. It is great for my 1800 watt invertor generator, I can run all the devices (not simultaneously) with it.

I'm going to add this: If you are a new electrical engineering student, the subject of circuit protection is a significant branch of the science, and technology that you are studying. It applies not only to your house, but from the little circuit that you might want to build, to the entire power network that supplies your home your city, and your nation.

When I had a new bathroom built, I thought it was also a good idea to redo the electrics. I discovered that I had a mains leadin rated at 240V 40A only. The electric stove alone was on a 30A sub circuit. Also sub circuits used wire fuses. Switchboard box was wood with asbestos lining and mounting board was made of pitch-impregnated asbestos.

Got the electrician in and for $1600 and peace of mind, I got a new mains leadin rated at 80A, a new plastic switchboard with circuit breakers, and MEN earth leakage breakers tripping at 30mA . Regs insisted that he test all sub circuits, powered and unpowered. They all passed. Can't ask better than that.

Do not be happy you got a new plastic switchboard! The wiring regs here were amended Jan 2016, so that all domestic distribution boards must be non-combustible, in practice - steel.

Reason was - London Fire Brigade was getting 3 home fires a week (pattern repeated across country) due to fires in dis. bd. Since many such are under stairs, cutting off [burning] escape route, deaths resulted, including firemen trying to reach trapped people.

Major basic cause was overheating of main connections - joints not tight enough plus increased loading due to more electrical kit - especially electric showers - with big loads.

Tests showed plastic enclosures just melted/sagged, letting flames out. Although tests with existing steel enclosures showed the ""circuit breaker" holes in steel did not let dangerous flame out, all new steel enclosures have a steel cover/door over breakers. I note that even recently installed 3 phase steel boards have all-plastic catches to hold steel door shut.

Looking back over my time with electricity, home dis boards have moved from wood to thermo-setting plastic [which at least will not deform or melt so easily] to thermo plastics which soften & let hot parts move together.

Sure, the modern plastics have fire-retardants, but that just means they have to be hotter to burn & make more toxic fumes & smoke. Nearly all common plastics burn and are made from oil & give out heat equivalent to same weight of motor car fuel.

Will those plastic MCBs still work OK if overheated? Particularly RCDs and RCBOs [earth leakage protection, usually 30 mA] which now are electronic - is the electronics designed to trip on over-temperature?

I look at a 50 year old dis board/wiring in a community centre I know and consider if new gear will be a total improvement. It is heavy steel with a strong door held shut by two steel wing-nuts; fuses are rewirable in porcelain with asbestos inserts - nothing in there which can burn except the cables and minimal busbar insulation. Because the fuses were re-wirable, wires were 50% more cross-section for the same current than with cartridge fuses or breakers - that makes for a much longer actual service life when no-one overloads the circuit & less volt drop.

Looking at national statistics, population 60 million, only 20 people a year die due to electrocution, but 2.5 million get a shock, with 350,000 serious injuries. About 50 die in domestic 20,000 fires started by electricity only 10% of which are due to fixed installation rather than an appliance.

Since you are an electrical student you must know the maximum safe current capacities of the electrical cables installed in your home now. Next is for you to buy a good ammeter/voltmeter tester. Last is for you to turn on all your electrical loads at the same time and patiently take measurements of all the electrical supply wires leading to the appliances. Make a list and review.