Welcome to session 4 of our series, once again please let me know if this is useful. Many thanks to those who encourage this in our forum.

I would be delighted to have you contribute as a few have.

If you need electrical work done on your caravan or RV, get a qualified electrician or auto electrician to do it. Do not ever attempt it yourself, this stuff is dangerous and can kill you!

ACDC

Todays subject is not only a great rock band but the guts of electricity. The main "waveforms" we deal with are these two. 

DC

The simplest, my definition is a constant voltage delivered over a variety of loads (load being current draw) this ignores the fact that voltage will decrease as load increases in generators, batteries etc.

DC is delivered by batteries, DC Generators, DC power supplies and DC plug packs. The most common we as GNs use is 12 volts, however there are some installations of 24 volts.

AC

This is a a complex sinusoidal waveform. Big words that simply put mean the voltage/current is constantly changing over a period of time.

One way to describe AC is to look at a circle, there are 360 degrees in a flat circle. The best way to describe this is with a graph of voltage/current vs time with a zero line horizontal axis in the middle of the vertical voltage/current axis. Take a look at the video for clearer understanding.

In Australia our "frequency" meaning completed events over a period of time is 50 cycles (hertz) or events per second, therefore each cycle or event takes 50 milli seconds (or 50 one thousandth of a second) to complete the 360 degrees.

Now AC moves in one direction then reverses to move in the other direction via a sine wave. I encourage you to look at this youtube file.

www.youtube.com/watch?v=vN9aR2wKv0U

This one is OK and explains the difference in reasonably simple terms.

The big safety issue we all carry on about with AC, especially 240 volts, is the effect it has on our hearts if we get a shock. Because this current is changing in both directions so quickly, the heart, being an electrical operated organ, becomes confused (for the want of a better word) and stops its normal sinus rhythm and starts to "wobble" in what they call ventricular fibrillation, this rhythm will not pump blood into the brain and death can result if intervention is withheld (either CPR or the heart is stopped and reset by a defibrillator). So safety with this stuff is paramount if you want to live long and prosper.

Its simpler to get a sparkie to do your electrical work, only a very silly person, with a death wish, will do their own.

Your comments and encouragement are greatly appreciated so please feel free to comment.

Cheers