What power lines bring electricity to your home?

Answer 1

In the UK, the very large steel electricity pylons that you see stretching across the countryside carry around 400,000 Volts of electricity.

There is a directly proportional relationship between Voltage and Current - Increase voltage = Decrease in current and vice-versa.

The 400,000 volts in these primary power lines from the electricity generating stations is necessary in order to transmit the electricity over large distances without too much energy being lost as heat. If the voltage was lower then the current would be higher and much thicker cables would be needed to carry the energy without too much heat loss.

The 400,000 volt lines feed into Sub-Stations which are basically huge Transformers which step the voltage down to around 140,000 volts. The energy is then fed across smaller distances and along a number of routes to smaller sub-stations.

The next sub-stations step the voltage down to around 66,000 and/or 33,000 volts which in turn gets transmitted to smaller sub-stations still.

The next sub-stations step the voltage down to around 11,000 volts ... these are the smallest overhead power lines that you generally see running between the large wooden poles across the fields and around the outskirts of cities & towns.

Many 11,000 volt lines drop down into under-ground cables once they reach heavily populated areas like towns & cities simply due to the impracticability of overhead lines close to buildings.

The higher the voltage, the easier it is for the current to "jump" causing sparking or continuous arcing. 11,000 volts can quite easily spontaneously jump over a 1 metre gap in air and that distance can be increased dramatically if there is a high moisture content to the air.

The final stage - The 11,000 volt lines arrive (usually underground in towns/cities - overhead in more rural areas) to their final dropping transformers or mini sub-stations

where the energy gets dropped to it's final working voltage - 415 volts - 3-phase for commercial usage (Industrial estates etc') and 240 volts single phase - 240 volts for domestic use in your home.

120 volts is a common domestic level in many countries around the world and the voltages/step-down levels may vary accordingly but the principal is the same for the transmission of electricity across the board - very high voltages in the HT (High Tension) lines emanating from the generating stations - stepping down through a series of transforming sub-stations across the electricity grid until they reach the final LV (Low Voltage) lines which supply the end users.

It is also interesting to note that there are many safety devices throughout the grid at all levels ranging from huge one-shot fuses which blow with the aid of a small explosive charge to compressed gas activated remotely operated switches to devices known as Re-Closers which will trip out in the event of a short-circuit but which will automatically try to re-connect after a pre-designated time (usually 2 to 3 minutes) - most of these Re-Closers will only attempt to re-establish supply 2 or 3 times before tripping out subject to a manual (or in some cases remotely activated) reset once the source of the problem has been located and rectified by engineers.

Automatic Re-Closers can be useful in cases where for example, a small tree branch drops onto the overhead lines tripping the Re-Closer but bounces off causing only a temporary short-circuit. In this case, the Re-Closer will restore the supply to consumers very quickly without the expense of, or the need to wait for, engineers to come out to inspect the lines and restore the supply manually.

Answer 2

Power lines that bring electricity to homes are typically part of the local electrical grid system operated by utility companies. These power lines transmit electricity from substations to residential areas, where it is further distributed through neighborhood transformers before entering homes through service lines.

Answer 3

yes

Answer 4

Yes.