Re: Exciting electrical safety demo by Network Manager.

Karen,

First I must add my caution to the idea of giving an exciting demo for 
the purpose of showing dangers. My experience is that the 14 year 
age group has difficulty in separating those two concepts. If, however, 
you believe that your group would not be placed in danger by 
repeating your demo for their friends and family, my suggestions 
follow.

What you're after is an actual cooking effect. I have been involved with 
competition where we were to construct such a device. This does 
happen at 120 volts which is the line pressure in the USA. Our 
solution is to plug directly into the wall outlet. You're quite correct to 
think that 48 volts will not do an exciting job. However, for your 
purposes would not the thought of a sizzle generate some caution in 
the students?

If you still intend to cook meat by passing a current through it, 
consider this. I would not want to plug a sausage directly into 240 
volts (if that is your local option). However, two sausages in series 
would serve as a voltage divider and act as though each were 
plugged into half of the voltage. Three, if necessary, would divide the 
line voltage into thirds. You will want to determine this before doing it 
in front of your students. Done properly, the electrodes used to 
connect the sausage will heat up most and sear the meat at the point 
of contact. As this contact dries out, the resistance will increase, the 
current will decrease and the cooking will slow or stop. Just 
remember to disconnect the power or you will be the fresh meat that 
starts the process over again.

My final regards are to emphasize the caution rather than the 
excitement.