borrowed neutral

no such thing in the electrical industry....however, there is a 'shared neutral'. Big difference.

It is only dangerous to "Bubba", who is confused with anything other that 2 wire romex.

Maybe someone "invented" the term to describe a load connected to a HOT in one cable and a NEUTRAL in another cable.

Slight OT: The air handler of my heatpump runs off 240 volts and nothing requires 120. BUT someone decided to have the condensate pump run off the same circuit but he needed a neutral for the 120 volt pump. No problem: he just used the ground! (Yes, it was a bad idea from many prospectives! The only protection for the #16 wire to the pump was a 60 amp breaker!)

That someone was most likely the HVAC installer. I see that crap all the time. 240V condensate pumps are readily available, but with a heat pump, you'd need to employ a tap feeding a disconnect w/OCD or a separate circuit.

Maybe this is just a UK term? I've heard it used very often.

A borrowed neutral is where a neutral is used from another circuit.

This makes isolation and fault finding difficult and also can be dangerous where the neutral is 'borrowed' from a circuit of lower current carrying capacity.

sQuick