Which of the following is a common safety practice in electrical installations?

Bonding all non-current carrying metal parts is a fundamental safety practice in electrical installations. This process involves connecting these metal components to ensure they share the same electrical potential. The purpose of bonding is to prevent electric shock hazards and to ensure that in the event of a fault, such as a short circuit or equipment failure, any stray voltage is safely directed back to the ground. This reduces the risk of electrical shock to personnel and also helps in clearing faults quickly, which can minimize the risk of fire or equipment damage.

The other practices mentioned may seem practical in isolation but do not conform to best safety practices. Using oversized conductors can be beneficial to some extent but does not address safety concerns directly related to grounding and bonding, which are critical in protecting against faults. Securing wires loosely is not advisable as it can lead to wear and tear, and creates a hazard by allowing movement that could stress connections. Using one type of circuit breaker for all applications disregards the necessity for specific ratings and types suited to varying loads and conditions, which could compromise safety and operational efficiency.