Final answer:
Electrical safety protocols for working with high-power electrical circuits include checking for zero voltage using the back of the hand, understanding series circuits in holiday lights, and using meters to measure electrical quantities safely.
Step-by-step explanation:
The question seems to revolve around the maintenance and safety checks when working with electrical circuits, specifically those involving power transmission lines or light strings. First, it is important to ensure the voltage is zero before touching the lines. Experts touch the line with the back of their hand because if the line were live, their muscles would contract, pulling their hand away and preventing them from grasping it, which could happen if they used the palm.
In terms of holiday lights wired in series, if one old-style bulb burns out and breaks the connection, all of the bulbs will go out. Each bulb would normally operate at 3 volts (120 V divided by 40 bulbs). However, if the bulbs are the modern type that short circuits when burnt out, the rest will continue to function and the voltage for each remaining bulb would slightly increase (120 V divided by 39 bulbs).
When testing circuit set-ups, it's crucial to check points that should have the same potential and use meters correctly to measure electrical quantities, starting with the highest scale to prevent damage to the meter.