Guide to the Canadian Electrical Code, Part I — Instalment 38

 

June 11, 2018

By William (Bill) Burr

In this article: Section 76 — Temporary Wiring. Sometimes it is impracticable to follow the rules for permanent installations when installing temporary wiring for construction or demolition projects. In many instances the wiring needs to be portable, flexible, and easily modified. In addition to this section, Appendix G references Section 5.6.1.9. (3) of the National Fire Code of Canada, 2015, Temporary Electrical Installations on Construction and Demolition Sites.

Also in this article: a correction to the previous article on Section 74 — Airport Installations.

Rule 76-000 notes that this is a supplementary or amendatory section of the code and applies to temporary wiring installations for buildings or projects under construction or demolition and experimental or testing facilities of a temporary nature. Section 76 does not apply to temporary installations in amusement parks, midways, carnivals, film and TV sets, TV remote broadcasting sites, home shows, live theatre, and travelling shows that are held indoors, outdoors, or in tents, which are covered by Section 66.

Rule 76-002 requires that conductors be

• selected in accordance with Section 12, rules 12-402(1) or 12-406(1) and power supply cable or flexible, outdoor, extra-hard usage cord conductors
• insulated other than as permitted by rules 6-308, 10-112, and 10-116
• installed in accordance with Sections 6, 10, and 36 for service conductors
• supported on poles spaced at not more than the allowable span for the type of overhead conductor

Rule 76-004 requires that all grounding and bonding be in accordance with Section 10.

Rule 76-006 specifies that where service entrance equipment is installed outdoors it must be

• accessible to only authorized persons
• lockable
• protected from weather and mechanical damage
• not exceed 200 amps mounted on a single pole

Rule 76-008 provides that distribution centres

• have adequate capacity and number of branch circuits in accordance with Section 14
• be of weatherproof construction or installed in a weatherproof building
• be mounted in an upright position

Rule 76-010 requires that feeders supplying distribution centres be

• installed armoured cable or equivalent
• installed in outdoor, extra-hard usage flexible cord or power supply cable containing a bonding conductor in accordance with 12-402(1) or 12-406(1) for a portable distribution centre
• protected from mechanical damage
• protected with suitable over-current devices and a disconnecting means

Rule 76-012 governs the installation of branch circuits and requires that

• non-metallic-sheathed cable be installed in accordance with Rules 12-500 to 12-526
• lighting branch circuits be kept separate from power branch circuits
• luminaires or lampholders be of a type and installed in compliance with Section 30
• the connected load of each lighting branch circuit may not exceed 80% of the circuit breaker rating in accordance with rule 30-104
• power branch circuits be provided with separate circuits for
  • motors sized and protected in accordance with Section 28
  • known loads limited to 80% of the rating of the circuit breaker
  • general-use receptacles with the breaker not exceeding the rating of the lowest rated receptacle

Rule 76-014 specifies that temporary installations must be separate and not interconnected with any circuits of the permanent installation without special permission as per rule 2-030.

Rule 76-016 states that all CSA configuration 5-15R or 5-20R receptacles be protected by a Class A GFCI.

In the next instalment, we will be discussing Section 78 — Marine Wharves, Docking Facilities, Fixed and Floating Piers, and Boathouses.

Correction to the previous article on Section 74 — Airport Installations

In my last instalment on airport installations, I erroneously stated that the ground counterpoise was provided to protect service personnel from touch voltages when repairing or replacing broken luminaires. This is not correct. The counterpoise, although connected to isolating transformer ground terminal, lighting unit stakes, and ground electrodes, is not a safety ground as used in conventional electrical systems. Nor does it represent a bonding to ground, as the series lighting system is an ungrounded system. The series circuits are capable of handling multiple grounds without tripping. The ground counterpoise is provided to protect the series lighting system from lightning strikes. When repairing or replacing parts of the lighting system, service personnel should isolate and lock-out the system. If the series circuit cannot be locked out due to operational limitations, the workers should wear the proper PPE including the proper class of high voltage insulating gloves for any contact with the equipment on the circuit. Thanks to Murray Ames, Campbell River Airport Electrician, for pointing out this important distinction for me. Murray is one of the instructors for the Airfield Lighting Maintenance course for airport electricians held at the airfield lighting training facility at the airport in Campbell River, BC.

William (Bill) Burr is the former Chair of the Canadian Advisory Council on Electrical Safety (CACES), former Director of Electrical and Elevator Safety for the Province of BC, and former Director of Electrical and Gas Standards Development and former Director of Conformity Assessment at CSA Group. Bill can be reached at Burr and Associates Consulting; billburr@gmail.com

* The source for this series of articles is the Canadian Electrical Code, Part I, published by CSA.

**Note the CEC Handbook is also published by CSA.