Getting a grip on vertical conductor supports – Code File, June 2025
Categories: Canada
July 24, 2025 – Due to government incentives, a growing renter population, rising rents and other factors, we see that developers are increasingly prioritizing the construction of high-rise apartment buildings.
An RLB Crane Index* report shows that Ontario’s operating tower crane count is increasing, with the City of Toronto currently holding the top spot of the 14 cities surveyed in Canada and the U.S.
With so many tall buildings being erected, it’s important to remember that conductors—whether installed in a raceway or contained in an armoured or sheathed cable assembly—require special consideration for their support when run vertically over extended distances.
There are distinct differences in the acceptable means of supporting these conductors, which are determined by the installation method and described in Canadian Electrical Code-Part I, Rule 12-120 “Supporting of conductors”.
Fun fact: the earliest version of Rule 12-120 appeared in the first edition of the Canadian Electrical Code. In 1927, Rule 503(p) addressed vertical conductor support in metal conduit work by specifying support intervals based on the size of the conductor.
Today, this rule continues to provide support requirements to ensure that vertical conductors will not slip due to their weight under gravity and experience damage, which can be caused by either inadequate supporting means or by overhanging the conductor on the edges of equipment or fittings.
Rule 12-120 also ensures equipment and terminations will not be subjected to damaging strain imposed by the conductor’s weight.
Raceways
For raceway installations, Table 21 prescribes the acceptable support intervals based on the conductor size and material. Wedge-type grips (Figure 1) are one acceptable and commonly employed means for complying with code requirements, but there are other acceptable solutions that are approved for the purpose.
The support means must maintain the continuity of the raceway, be approved for use in Canada, be installed in accordance with the manufacturer’s instructions, and be independent of terminations. It is not permitted to support conductors in raceways by means of periodic offset bends or by any ratio of horizontal to vertical distances (which are only recognized for cable installations).
Armoured or sheathed
For armoured or sheathed cable installations, Table 21 again determines acceptable intervals for the internal conductor assembly supports. Like conductors in raceways, the support may be provided using approved manufactured products, but additional support options are available. One support method involves incorporating the equivalent of not less than the equivalent of a 90º bend at the specified interval found in Table 21.
Rule 12-120 also provides for two other methods, neither of which rely on specific intervals for the supporting means. The first option is to include a horizontal run of the cable that is at least equal in length to the vertical run. The second is to use a cable specifically built for vertical runs i.e. its inner conductor core has been designed to prevent slippage from the armour or sheath.
Planning the support of vertical conductor runs to ensure they meet code requirements is of paramount importance at the design stage of a project. This will ensure that any necessary enclosures housing the supporting means remain accessible (as required by Rule 12-3014), and that the support method can be implemented within the specific building construction.
* Crane Index North America, Q1 2025, Rider Levett Bucknall.
Diana Madill is a Red Seal Electrician (309A), Master Electrician, and Canadian Certified Electrical Inspector, and currently serves as a technical advisor at Ontario’s Electrical Safety Authority. She is a member of several CE Code-Part I Section committees, as well as CSA Z32. Diana also sits on the Ontario Provincial Code Committee and is a member of the IAEI-Ontario Section board.
