Disconnect (the / zero article) power before attempting to repair electrical equipment

Could you please advise which article should be used in the below sentence?

I and my friend are doing an exercise of filling suitable article(s) (a / an / the / no article) into the blank of the sentence:

You should disconnect ____ power before attempting to repair electrical equipment.

Both of us agree that indefinite articles 'a' and 'an' will not be used before uncountable nouns like power in the above sentence. However, we have different views on the other choices.

For me, I don't use any article because

When we refer to general ideas, plurals or uncountable nouns we do not use THE.
Source: Grammar.cl

and I also showed my friend some example sentences from Google:

This starts in the home, where you should disconnect power before performing any work like replacing a light fixture or an outlet.
Source: powerlines.seattle.gov

My friend disagrees with me. She explains that without definite article "the", the sentence in the exercise means you should disconnect all power, even the power from equipment which you don't repair. This doesn't make sense. That's why she thinks "the" should be filled into the blank to mean that you should disconnect the power which is relevant to the electrical equipment you want to repair. Fortunately, she found the original sentence from Cambridge dictionary:

You should disconnect the power before attempting to repair electrical equipment.
Source: dictionary.cambridge.org

Answer

Cambridge is correct. The definite article is used to indicate a known entity -- in other words, the reader should know which power is meant. This is not a "general idea" -- this is a recognizable instance of something that exists in the real world.

The meaning of "the power" depends on context. If you are working on an entire house, then you should disconnect power to the entire house. If you are working on a specific area of the house, disconnect the power to that area. If you are working on a specific device, disconnect the power to that device.

In other words, there should be no risk of you touching live wires while you work.

Of course there is some ambiguity here, but you're expected to interpret using common sense. If you're just replacing a power socket, you don't knock out power to your entire neighborhood.