Electrical safety: Changes made to the 2018 Canadian Electrical Code

by | Nov 6, 2018 | Electrical Safety

Electrical safety:

Major changes made to the 2018 Canadian Eletrical Code for conductor gauges

 

Several changes have been made to the 2018 version of the Canadian Electrical Code regarding the admissible current values in tables 1 to 4, as well as the new method to be used taking into account the temperature of terminations and equipment. This blog will thus allow you to better understand this new method for sizing of conductors.

The values for admissible current assigned in tables 1 to 4 have been lowered in comparison with older regulations. In addition, the calculation method for conductor sizing has been modified. The lowest of the following values must now be taken into account:

  • Maximum permissible temperature at upstream equipment terminations
  • Maximum permissible temperature at downstream equipment terminations
  • Maximum temperature allowed by the conductor insulations.

Here are 6 examples that aim to determine the right conductor gauge in accordance with the new methods:

The following tables are drawn from the Régie du bâtiment du Québec’s explanatory booklet which is available online:

Table 1: Table of admissible currents drawn from the RBQ’s explanatory booklet

Example 1:

If 75°C is indicated on the circuit breaker and 90°C on the terminal block for an admissible current of at least 150 A for three aluminium conductors in a pipe and the necessity for conductors with a temperature of at least 90°C is not mentioned on the powered equipment, use of 000 AWG sized RW75 type conductors is allowed. Additionally, use of 000 AWG sized RW90 type conductors is allowed but use of 00 AWG sized RW90 type conductors is not.

Example 2:

If conductor temperature is not mentioned on the circuit breaker, the terminal block or the powered equipment, it must be estimated: 60°C for equipment of at most 100 A for 1 AWG sized conductors or smaller, 75°C for equipment over 100 A for conductors of larger sizes than 1 AWG. For three aluminium conductors in a pipe and an admissible current of 135 A with no temperature data present, size 00 AWG RW75 type conductors or size 00 AWG RW90 type conductors would be admissible.

Example 3:

If 60°C is indicated on the circuit breaker for an admissible current of 135 A and no other data is provided on the powered equipment, 0000 AWG sized RW75 type conductors or 0000AWG sized RW90 type conductors would be admissible for three aluminium conductors in a pipe.

Example 4:

If 75°C is indicated on the circuit breaker and 90°C on the terminal block for an admissible current of at least 75 A for three copper conductors in a pipe and if the necessity for conductors with a temperature of at least 90°C is not indicated on the powered equipment, use of 3 AWG sized RW75 type conductors would be admissible. Additionally, use of 3 AWG sized RW90 type conductors would be admissible, but not the use of 6 AWG sized RW90 type conductors.

Example 5:

If conductor temperature is not mentioned on the circuit breaker, the terminal block or the powered equipment, it must be estimated: 60°C for equipment of at most 100 A for conductors of 1 AWG or smaller, 75°C for the equipment of more than 100A for conductors larger than 1 AWG. For three copper conductors in a pipe and an admissible current of 75 A with no temperature data present, 3 AWG sized RW60, RW75 or RW90 type conductors would be admissible.

Example 6:

If 75°C is indicated on the circuit breaker, 90°C on the terminal block and 75°C on the powered equipment for an admissible current of 75 A, 4 AWG sized RW75 or RW90 type conductors would be admissible for three copper conductors in a pipe.

The correction factors of tables 5A to 5D to be applied to tables 1 to 4 have retained the same values.

It is also clearly indicated to refer to the requirements of the IEEE 835 standard to determine the admissible current values if no corresponding table exists.

Work started before April 1st 2019 can be executed in accordance with the old or the new regulations.

Please do not hesitate to contact us for further information!

 

References:

Code de construction du Québec, Chapitre V – Électricité – Code canadien de l’électricité, Première partie (Vingt-troisième édition) et Modification du Québec.

Cahier explicatif de la régie du bâtiment du Québec (https://www.rbq.gouv.qc.ca/fileadmin/medias/pdf/Publications/francais/cahier-explicatif-changement-electricite-2018.pdf)

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Intervention Prévention concentrates its operations in the field of work safety, offering specialized services following Standards CSA Z462 – Workplace Electrical Safety, CSA Z460 – Control of Hazardous Energy: Lock-out and Other Methods, and CSA Z432 – Safeguarding of Machinery.

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