Guide to the Canadian Electrical Code, Part I — Instalment 31

 

Dec 11, 2017

By William (Bill) Burr

In this article: Section 62 — Fixed electric heating systems

62-000 Scope states that this is a supplementary or amendatory section of the code and applies to the installation of electric heating systems for space heating, surface heating and other electric heating system applications. Appendix B and the CE Code Handbook provide additional information.

General

The General requirements, Rules 62-100 to 62-128 apply to all heating system installations.

Rule 62-102 mandates that, in addition to the rules of this section, the manufacturer’s installation instructions, which are part of the approval of the heating device, must be followed. In addition, to ensure equipotential grounding plane safety, all non-current-carrying metal parts including braids, shields, and sheaths must be bonded to ground.

Rule 62-104 provides Special Terminology definitions that apply to equipment specific to this (For additional information see the usage marking table in Appendix B).

Rule 62-106 requires that electric heating equipment installed in special hazardous, wet or corrosive locations be specifically marked as suitable for that location.

Rule 62-108 requires that branch circuit connections be made in accessible non-combustible terminal fittings or boxes with the branch circuit conductor meeting the temperature rating specified by the manufacturer, if the point of connection can exceed 60 °C, and not less than 500mm long if a tap conductor is used.

Rule 62-110 requires that branch circuit conductors must have an ampacity and insulation temperature rating consistent with the connected load, and, be used solely for heating device sets, except for a heat lamp that is not a sole source of heat and used in a luminaire approved for the purpose or mounted on an outlet box. Combination units containing heating, ventilation and/or lighting are heating device sets.

Rule 62-112 specifies that heating devices be installed with sufficient clearance from combustible materials to prevent them being subjected to temperatures more than 90 °C. Table 67 provides some tabulated clearances

Rule 62-114 outlines the overcurrent protection and grouping of heating devices in accordance with rule 8-104 (the CEC Handbook provides a table):

• every heating device with input of more than 30 A must be supplied by a separate dedicated branch circuit

• in residential occupancies, two or more heating devices used for space heating may be connected to a branch circuit rated up to 30A

• in other than residential occupancies:

o two or more heating devices may be grouped on a branch circuit rated up to, 60 A

o in a balanced three-phase arrangement, three heating devices may be grouped on a branch rated more than 60 A

• non-heating leads of heating cable sets, heating fixtures, and taps to heating cable sets, heating fixtures, and strip systems of two or more heating devices grouped on a single branch circuit, must have an ampacity not less than one-third the rating of the branch circuit and must be not more than 7.5 m in length, except as per Rule 4-008

• the calculation of the load for service, feeders, or branch circuits used solely for the supply of energy to heating device sets and determined under Rule 62-118, must meet the continuous ratings of rule 8-104

• the ampacity for service, feeder, or branch circuit conductors supplying only fixed resistance heating loads, may be less than the overcurrent protection, provided it is not less than the load; and at least 80% of the overcurrent protection. Note: that a breaker rated up to 125% of the conductor ampacity may be used if a standard size is not available

Rule 62-116 outlines ground fault protection for electric heating systems that this is equipment protection against fire hazard and not for shock hazard. The difference between ground fault (GF) protection and circuit interruption (GFCI) is the trip level setting (Appendix B and the CEC Handbook provide additional information):

• for de-energization of ungrounded conductors of electric heating cable sets, heating panel sets, and fixed infrared radiant heaters of the metal-sheath glowing element type the GF protection should be set low enough to allow normal operation of the heater, but, trip if there is a sustained high resistance arcing fault

• for heating equipment in industrial establishments where there is maintenance by qualified persons, ground fault detection is set to indicate or sound an alarm and allow maintenance to investigate and repair

• for heating cable sets and panel sets connected to a Class 1 extra-low-voltage power circuit supplied from the secondary of an isolating transformer that has no direct electrical connection between the primary and secondary windings, is supplied from a branch circuit operating at not more than 150 volts-to-ground, and is not grounded, no GF protection is required

Rule 62-118 provides the demand factors for service conductors and feeders for heating device circuits as follows: (the CEC Handbook provides some calculation examples)

• continuous heating devices only, use 100% of current ratings of all supplied devices

• cyclic heating devices only, use 100% of maximum load connected at any one time

• heating devices in residential occupancies provided with automatic thermostatic control devices in each heated area, use 100% for first 10KW, plus 75% of the rest

• electric thermal storage heating systems, duct heaters, or electric furnaces, use 100%

• combined loads of heating and other equipment:

o residential occupancy use, as above plus other equipment with Section 8 demand factors

o other occupancies, use 75% of total heating load plus other equipment with Section 8 demand factors

o Where the non-heating load, including demand factors, is less than 25% of the heating load, use the total load with no demand factor on the heating portion

Rule 62-120 requires that line voltage temperature control devices be rated for the full current of the equipment they control and, when turned to a marked OFF position either manually or automatically, interrupt the line current and open all ungrounded conductors of the heating circuit.

Rule 62-122 specifies that series heating cable sets must be complete assemblies and have permanent markings not more than 75 mm from the supply end of the non-heating leads. This also ensures proper installation as per 62-124.

Rule 62-124 provides the installation requirements for series heating cable sets and specifies that the heating portion, including connections, be installed in the heating area and not closer than 200 mm to any other heat-producing equipment or luminaire. It also specifies that the series heating cable set not be shortened and must bear the marking as per 62-122 except in an industrial establishment with conditions as described in 62-126.

Rule 62-126 permits that series heating cable sets at industrial establishments, where maintenance and supervision are done by qualified persons, may be

• repaired or spliced with manufacturer supplied kits if the length of the heating portion is not altered more than 3% and may be field assembled or modified with manufacturer supplied splice kits,

• field modified, or field assembled with manufacturer supplied splice and termination kits, provided that

o the design modification is reviewed by the manufacturer and a permanent record is retained

o a permanent tag with the new design information is attached

o tests for insulation resistance and verification of the finished heating cable set resistance are made

o the electrical rating is permanently marked in or on the junction box, on the heating cable; or on a permanent tag within 75 mm of the power connection

Rule 62-128 provides requirements for the installation of the non-heating leads of heating device sets, which includes:

• the manufacturer’s instructions, as outlined in 62-102

• rules of Section 12, installation in concrete or other subfloor assemblies

• the location of the joint between the heating portion and non-heating leads

Electric space-heating systems

Rules 62-200 to 62-222 provide the requirements for the installation of fixed electric space-heating systems. Table 67 outlines minimum clearances of space-heating systems as required by 62-200, 62-208, 62212 and 62-218. Additional guidance is provided in Appendix B

Rule 62-202 specifies that all space heating systems require temperature control and provides additional clearance, isolation or GFCI protection for temperature controls located in bathrooms.

Rule 62-204 mandates minimum separation of wiring of other circuits from heating devices, and an operating ambient of 50 °C, unless a minimum 50mm thickness of insulation is interposed, or the heating device is marked for a lesser clearance. Other conductors located in heated concrete slabs are operating in a 40 °C ambient.

Rule 62-206 requires that central units be installed

• accessible for repair and maintenance

• in large areas unless approved for installation in an alcove or closet

• in compliance with the clearances from combustible materials as specified on the nameplate

• with a single disconnecting means that opens all ungrounded conductors of the circuit supplying the controller and the central unit simultaneously

• with disconnecting means grouped, where more than one circuit is needed for the unit and controller, with signage on the central unit and located within sight of, and within 9 m of the central unit and the controller, or in the alcove or closet where the unit and controller are installed
Rule 62-208 governs the location of heating cable sets and heating panel sets and requires that they

• comply with the clearance requirements of Table 67

• not penetrate or pass through walls, partitions, floors, or similar structure

• may be in contact with thermal insulation but not run in or through thermal insulation

Rule 62-210 provides rules for the Installation of heating fixtures and requires that

• heat is not obstructed by the building structure

• temperatures may be up to 150 °C in non-combustible material and buildings, if the heating fixture is marked for this application

• connections must be accessible, without removal of the supports, for fixtures weighing more than 4.54 kg

• supports may be a wall outlet box, where the heating fixture does not exceed 13 kg, and may be a ceiling outlet box where the heating fixture does not exceed 23 kg, otherwise, independently of the outlet box or a suitable fixture hanger

• they are protected from mechanical damage or suitable for the application if installed less than 5.5 m above the floor in an arena, gymnasium, or similar location

• they are not used as a raceway for circuit conductors, except for the wiring channel of a baseboard heater for interconnection of adjacent fixtures on the same circuit

Rule 62-212 provides requirements for the Installation of heating cable sets and heating panel sets and specifies that:

• they be installed as per the clearances in rule 62-112 and Table 67

• connections necessary to assemble a heating panel set may be inaccessible after surface finishing materials are applied

• cutting, nailing or stapling only to be done at marked areas

• a label affixed to the panelboard identifying the branch circuits supplying heating cable and panel sets and warning that surfaces and locations must not be penetrated by nails, screws, or similar devices

Rule 62-214 specifies that heating cable sets Installed in plaster or other cementitious material must be completely, including heating portion and connection to non-heating leads, embedded in the non-combustible material and secured by non-damaging fastening devices suitable for the temperature involved.

Rule 62-216 specifies that heating cable and panel sets installed in gypsum board and other cementitious ceiling and wall installations must be run parallel to with clearance not less than 13 mm on each side of the joist, stud, or nailing strip, and the entire ceiling below covered with gypsum board or other cementitious materials up to 13 mm in thickness

Rule 62-218 specifies that heating cable sets and heating panel sets Installed under floor coverings must comply with the clearance requirements for installed heating systems given in Table 67 and with Rule 62-102 and be installed on floor surfaces that are smooth and flat and completely covered by the appropriate floor coverings. In dwelling units FCC non-heating leads may be used for connections to the branch circuit.

Rule 62-220 requires that where multiple infrared radiant heaters of the metal-sheath glowing element type are used on the same branch circuit, a single means of ground fault protection as described in Rule 62-116 may be used in the branch circuit.

Rule 62-222 requires that heaters for sauna rooms be

• marked as being suitable for the purpose

• installed in rooms that are built in accordance with the nameplate size specifications

• fastened securely in place ensuring the minimum safe clearances indicated on the nameplate are not reduced

• not installed below shower heads or water spray devices

• controlled by a timed cut-off switch having a maximum time setting of 1 h, with no override feature, mounted on the outside wall of the room, if not forming part of the sauna heater or cabinet, and that disconnects all ungrounded conductors in the circuit supplying the heater

Electric surface heating systems

Rule 62-300 outlines that Rules 62-302 to 62-314 apply to fixed surface heating systems for pipe heating, melting of snow or ice on roofs or concrete or asphalt surfaces, soil heating, and similar applications other than space heating.

Rule 62-302 requires that fixtures located exposed to rainfall be provided with a weatherproof enclosure.

Rule 62-304 requires that heating cables and heating panels installed below the heated surface:

• installed outdoors under the surface of driveways, sidewalks, and similar locations be embedded or covered to a depth of 50 mm minimum below the finished surface and surrounded by non-combustible material throughout their length, including the point of connection to the non-heating leads

• installed indoors and non-metallic, be not less than 25 mm from any uninsulated metal bodies located below the surface. Appendix B has some further guidance

Rule 62-306 requires heating cable sets on or wrapped around surfaces be secured in place by suitable, non-damaging fastening devices and installed in such a manner as to avoid damage from movement when wrapped over valves, equipment, or expansion joints in piping systems.

Rule 62-308 requires that heating and panel sets installed on non-metallic pipes, ducts, or vessels be controlled by a thermostat or other suitable temperature-limiting system so that it does not cause damage.

Rule 62-310 requires that heating panel sets installed on tanks, vessels, or pipes be secured in place by suitable fastening devices.

Rule 62-312 requires that permanent, legible caution labels be placed on the outermost surface of the thermal insulation or cladding of pipes, vessels, or ducts with electric heating to indicate that they are electrically traced and:

• be visible after installation

• be not more than 6 m apart on pipe and ducts

• be not more than 6 m apart measured circumferentially on tanks or vessels with not less than two labels per tank or vessel

• have additional caution labels on or near associated equipment that may have to be serviced

Rule 62-314 governs the requirements of skin effect heat tracing which is a special form of heating in which an insulated conductor is run inside a ferromagnetic envelope as part of a certified system and requires that skin effect trace heating conform to the following installation requirements:

• ferromagnetic envelopes, ferrous or non-ferrous metal raceways, boxes, fittings, supports, and support hardware may be installed in concrete or in direct contact with the earth

• the ferromagnetic envelope must be grounded at the power connection and end termination enclosure(s)

• the skin effect trace heating system must be supplied from an isolating transformer, with the secondary not grounded

• the provisions of Rule 10-106 do not apply to the installation of skin effect trace heating systems

• the junction box containing the connection to the distribution wiring must be accessible, however, other parts of a skin effect trace heating system, may be buried, embedded, or otherwise inaccessible

• the provisions of Rule 12-3022(7) do not apply

Other heating systems

Rules 62-400 to 62-410 apply to other applications of heating systems that are not space or surface heating systems such pipe internal heaters, immersion heaters; and hot water tanks.

Rule 62-400 requires heating cable and panel sets installed within pipes, ducts, or vessels to be

• suitable for the application

• pass through a suitable gland

• installed in such a way to prevent flooding of a metal raceway containing the non-heating leads if the gland fails

• controlled by a thermostat or other suitable temperature-limiting system to prevent damage to the pipe, duct, or vessel

Rule 62-402 requires that pipeline impedance heating equipment conform to the following:

• voltage applied to the piping must not exceed 30 V, and be supplied from an isolating-type transformer

• no part of the extra-low-voltage circuit, including the conductors and the piping in the loop used for heating, is to be bonded to ground

• pipe hangers must be made of insulating material or have insulating bushings

• pipes must have a minimum clearance of 100 mm from adjacent material, and other pipes, except from hangers or supports

• pipes passing through walls, floors, or ceilings, must be bushed with insulating bushings or have 100 mm of clearance as required above

• vertical runs must be firestopped and supported at each floor and every 6 m or at insulating hangers

• horizontal runs must be supported every 3 m

• pipes used as heating elements must be electrically insulated, guarded or shielded and protected from mechanical damage

• all pipes used for conductors in the electrical circuit must be of the same diameter and made of the same material

• joints must be as electrically conductive as the adjacent piping

Rule 62-404 requires that overcurrent protection of storage-tank water heaters and conductors comply with Rule 62-114.

Rule 62-406 outlines installation requirements for infrared drying lamps as follows:

• medium-base, unswitched, porcelain type or other luminaires approved for the purpose shall be permitted to be used with lamps rated at 300 W or less

• screwshell luminaires are not be used with lamps rated at more than 300 W unless approved for the purpose

• in industrial establishments, luminaires may be operated in series on circuits of more than 150 volts-to-ground where adequate spacings for the higher circuit voltage are provided

Rule 62-408 applies to induction and dielectric heating and requires that

• the overcurrent device in circuits supplying non-motor-generator equipment may be rated at not more than 200% of the ampacity of the circuit conductors

• A readily accessible disconnecting means, rated not less than the nameplate rating of the heating device, be provided to disconnect each heating device from its supply circuit, and be located within sight and within 9 m of the heating device, unless the disconnecting means can be locked in the open position

• A readily accessible disconnecting means, having a rating in accordance with Section 28, be provided for each generator or group of generators at a single location

• the supply circuit disconnecting means may be used as the disconnecting means if the circuit supplies only one motor-generator, vacuum tube, or solid-state converter

Rule 62-410 requires that a bare element water heater be:

• supplied from a grounded system

• permanently connected to a branch circuit that supplies no other equipment

• protected by a ground fault circuit interrupter of the Class A type

• not located within 1.5 m of the point of utilization of the heated water

In the next installment, we will be discussing Section 64 — Renewable energy systems.

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.
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