electrical system

Manager’s guide to electrical system maintenance

What to know about keeping the lights on
Thursday, February 6, 2020
By Gerard Gransaull

Canadians are lucky to enjoy a relatively robust and reliable electrical power infrastructure. Most of the time, we flick a switch and the lights turn on. The citizens of many other countries who experience frequent outages or fluctuating supply, however, are not so lucky. The stable nature of our infrastructure brings a certain predictable (yet inadvisable) complacency which quickly evaporates as soon as an emergency takes our grid off-line (not to mention, adults and kids alike break into a cold sweat over the spectre of a dead cell phone).

Still, the impact of electrical power outages is considerably more profound than inconvenient in condo property management. An absence of light and power can pose health and safety risks to residents, some of whom may need to be evacuated. This can disrupt lives and force unexpected expenses.

Individually, we can’t do much to ensure our electrical grid remains functional. Of course, reducing our electrical demand goes a long way to reducing strain on the grid, which can significantly lower the risk of utility equipment overloads, fires, and brown- and black-outs.

Electrical maintenance 101

At the building level, managers and board members have an essential role to play in keeping the system operating safely and the current flowing. Paramount to this is ensuring your electrical system is well maintained.

To plan for electrical system maintenance, it’s helpful to understand how power is delivered to and distributed around the building.

Main transformer

The utility’s power supply grid operates at high voltage, which reduces cost and improves efficiency. This could be 25,000V or more. Before power can be sent to the user, the voltage must be lowered to useful levels. Transformers are used to reduce the high voltage down to safer levels. Transformers are everywhere; you probably have several in your pocket or purse as the cube of a cell phone charger is one. Newer buildings are typically supplied with power at 600V.

This is useful for supplying large equipment such as chillers or elevators but is still high enough to be a significant safety risk. Much of a building’s needs will be handled by 120/208V (or 240V). For an individual suite or home, usable voltage is 120/240V (or 208V).

The main transformer for a building is often either in a below-ground vault or on-grade outside on a concrete pad. It is most often owned and maintained by the utility. In these cases, the condominium will not have access to the vault.

It is important to note that if a vault is within the condominium’s property lines, the condition of the vault is likely the condominium’s responsibility, even if the equipment in the vault belongs to the utility. It is important to be aware, then, that leakage into a vault or structural deterioration of a vault can damage the utility’s transformer, which can shut down power to the building or cause a fire. The condominium should arrange for access to the vault with the utility and their engineer at least once a year to check its condition. Look for water leakage, structural damage, flooding, overheating, or vermin.

For an exterior pad-mounted unit, the corporation typically owns the concrete pad upon which the transformer sits and the cables which travel underground to the building. Staff should check the pad for settlement or deterioration as the severe movement of the pad could stress cable connections, leading to loss of power, arcing, and/or fire.

It is becoming increasingly common for new condominiums to house and even own the high-voltage switchgear and the main transformer within the building. As a benefit, the utility will typically discount the hydro rate charged to the corporation.

Main distribution

Power from the main transformer is delivered to the main switchgear, which is a large building’s equivalent of the main breaker panel for a house. The switchgear consists of metal cabinets with internal power bars carrying electricity, and it breaks down the main service into smaller chunks for use by the building. Fuses or breakers act as safety switches. The main switchgear for a condominium building often includes switches for suite power risers, main mechanical equipment, elevators, generators, lighting, and motor starter centers.

If the main switchgear operates at 600V, the condominium will include additional transformers to reduce the power down to 120/208V for general use such as lights, plugs, etc. These are typically located in main and sub electrical rooms, as well as in-service areas such as the elevator machine room and a mechanical penthouse.

From the main switchgear, electricity for common area (“house”) loads is sent to splitter boxes, disconnects, and panelboards which contain circuit breakers (or fuses) supplying discrete loads such as lighting, receptacles, electric water heaters, and the like.

In a condominium tower, power from the switchgear is often split into risers, which distribute it vertically through stacked electrical closets on the floors. A typical closet includes a main panelboard, which contains the suite breakers.

Electrical system maintenance

Maintenance of the main distribution equipment should include both regular inspections by building staff, and annual or bi-annual interventions by electrical professionals.

Elements of regular maintenance include the following:

Visual review

Regular visual inspections of all electrical rooms and electrical closets are important. This can be done by the property manager, superintendent, or another qualified person and is recommended monthly. Consider the following when conducting this review:

  1. Ensure access to the area is effectively locked and that the lock is tamper-proof.
  2. Keep storage out of electrical rooms, maintain at least a 1m free-clearance space in front of distribution equipment, and keep storage off transformers.
  3. Ensure the room is not leaking or damaged; add drip pans below pipes and drains to stop leaks from dripping onto live electrical equipment.
  4. Check your equipment for rust, water stains, scorch marks, overheating, dust, and dirt.
  5. Note the room temperature, as it should not be excessively hot. If the room has an exhaust fan, test its operation (look for a switch or thermostat on the wall).
  6. Ensure that covers on electrical panels are present, secure, and free of gaps or openings into which fingers can be inserted or out of which fire can escape.

Remember, this is a visual review. Stay a few feet back, and don’t touch anything.

Thermal Scans

In normal operation, electrical equipment may be warm but should not be hot. Periodic scans by a qualified infrared thermographer can reveal which parts of a switchgear, panelboard, and similar components are running hot. This allows the problem to be diagnosed and repairs made before they escalate into equipment damage or fire. While the cost-vs-benefit is easily defendable to allow this to be an annual exercise, buildings under 20 years of age can reasonably defer to every two or three years.

Switchgear maintenance

Most large buildings have at least one main switchgear and may have several suite power riser transformers. Some also include high-voltage gear and the main power transformer. Maintenance of this equipment, in addition to regular thermal scans, includes visual inspection for immediate problems, testing trip setpoints, exercising and lubricating switches, cleaning the interior of the gear, and tightening connections to manufacturer’s specifications. The frequency of this hands-on servicing is dependent on equipment age, site history, and ownership risk tolerance, from every three to five years for newer sites up to annually as the equipment ages beyond about 20 years.

Arc-flash studies

Arcing is the unwanted flow of electricity across air, due to damage or ground faults. Arcing is very destructive, leading to shock and fire. People working around or on live electrical equipment, especially if the equipment is at high voltage, are at risk of arc-flashes. The Canadian Standards Association (CSA) has implemented a new CSA Z462 Workplace Electrical Safety Standard. CSA Z462 is based on NFPA 70E, and provides guidance on the assessment of electrical hazards and design of safe workspaces around electrical power systems. An arc flash study categorizes electrical equipment by risk level and allows workers to choose appropriate protective gear. The study should be reviewed every five years or when major changes are made to the system. While arguably not mandatory for condominiums to perform, having the system’s arc flash risk base-lined reduces risk to workers and the corporation.

Reserve fund

Proactive maintenance of electrical equipment helps maximize equipment lifespan. Eventually, the replacement of old equipment will be required, typically, after about 35 to 45 years of use. Smaller components can fail sooner since disconnects, breakers, or panelboards may only last 15 to 25 years. Owners should ensure their reserve fund has ample allowances for replacement of large, discrete equipment such as transformers, switchgear, MCCs, and related equipment. Owners would also do well to undertake these projects proactively as planning for replacement of the main transformer, for example, will allow arranging for temporary power and getting competitive pricing via specification and tender. The opposite approach is to wait until the equipment fails, which will guarantee much more considerable inconvenience and significantly higher costs.

Have a plan

Establishing a comprehensive maintenance plan with your electrical professional ensures a condominium’s power system operates safely and reliably and will maximize its lifespan. Perhaps most importantly, it will reduce the risk of sudden, catastrophic failure, a disruptive and potentially dangerous occurrence.

Gerard Gransaull, P. Eng. is Director, Building Science – Building Condition Assessment, for WSP in Canada.

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