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Demystifying grounding

lectricit Qubec - Par Michel Chartier, ing. ATD

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The use, installation and connection of grounding and continuous grounds are regulated by the Québec Electric Code. Industry best practices surpass this code by following standards laid out by the Institute of Electrical and Electronics Engineers (IEEE), the former FIPPS and by manufacturers.

Over the years, we have observed general incomprehension around grounding when it comes to connecting distinct systems or installing dedicated wire-grounded electrical outlets.

As you will see, however, any understanding of grounding and continuous ground stems from Kirchhoff’s voltage and current laws. These laws share the basic principle of all universal phenomena: nothing is lost and nothing is created. We must apply this principle to determine ahead of time the paths stray current will take should equipment malfunction.

The simpler of the two concepts: grounding

The term “grounding” should only be used for connection to the ground of the XO outlet of an electrical distribution network in order to ensure it is not floating. This connection can be found on all new distribution transformers with secondary winding (Y or ZigZag).

This connection is crucial. It guarantees the stability and integrity of the current and therefore the safety of grid workers.

Grounding will serve as the sole return path to the transformer should a malfunction occur on one of the connected loads. More specifically, the principle that “nothing is lost, nothing is created” helps us understand that, according to Kirchhoff’s current law, the current flowing from a transformer towards a load must necessarily return to this same transformer.

If a short circuit occurs between phase and earth for equipment grounded to a transformer, for example, the diverted current will return to the transformer. Imagine the impact this return current could have if the ground connection is inadequate!

The following article will show a couple figures illustrating safe and dangerous paths the current could take.