Use and Set-Up of Large Tents
Overview
This bulletin describes safety guidelines for using and setting up large tents. Large tents are generally considered to be marquee, maxi-frame, super-frame, or SaddleSpan tents that are at least 20 ft. × 20 ft. (400 sq. ft.) in size and require assembly on site.
Hazards
Here are some things to consider when working with large tents:
- Electrical power lines — When installing or dismantling tents, making contact with high-voltage power lines or encroaching on the limits of approach around power lines can result in serious or fatal injuries.
- Electrical induction — Placing a tent too close to high-voltage lines poses a risk of electrical induction. If the tent is not properly grounded, voltage can gather in the metal frame and may result in a mild electric shock to workers if the tent is not grounded.
- Flammables (e.g., hair, makeup, costumes) — Hair spray and makeup brush cleaner contain butane and alcohol, which are both flammable. Costumes may include flammable cellulose fibres, such as cotton, linen, or viscose.
- Fire — Tents don’t have fire compartments to keep fires from spreading, so it’s important to consider the stability, resistance, and fire reaction of tent materials.
- Surface grade and composition — Hills and uneven surfaces can present slope hazards. Parking lots can make staking difficult. On asphalt surfaces, weights used to hold down tents can shift in windy conditions.
- Overhead obstructions (e.g., telephone lines, exterior lighting sources, trees) — Verify that there are no overhead obstructions that will interfere with the safe setup of the tent.
- Underground lines (e.g., electrical, gas, and irrigation lines) — When staking large tents, workers often use impact tools to drive in the stakes, which can potentially rupture an underground line and result in a fire, power outage, or flooding.
- Weather (e.g., windstorms, heavy snowfalls) — Approximately 70% of tent claims are weather related. High winds can damage or catch tents. Snow load is a major concern for tent collapse.
- Musculoskeletal injury (MSI) — The MSI risk associated with erecting, moving, or dismantling tents typically arises from the physical demands of lifting, bending, twisting, and repetitive motions. These actions can strain muscles, ligaments, and joints. Prolonged or improper handling can lead to strains, sprains, or more serious injuries, especially if the task involves awkward postures, excessive force, or poor lifting techniques.
Risk assessments
When planning any activity where there will be a tent occupied by people or equipment, the first step is to conduct a risk assessment. A risk assessment will help identify hazards and the risks associated with them. Risk assessments are also required when there are changes in the workplace, such as a new location or new equipment.
When setting up a large tent, consider the following questions:
- Can you identify high-voltage power lines? Do you know their voltage? Could you come within 6 m (20 ft.) of the power lines with long tent structural poles or other equipment? Refer to Table 19–1A.
- Are tents set up underneath high-voltage power lines? If so, a ground should be installed to control electrical induction.
- What wind speed is the tent rated to withstand? When must the tent be disassembled? Refer to the tent manufacturer’s specifications.
- Have you checked the weather forecast? Consider the effects of rain, lightning, wind, and snow. You may need extra anchoring or weighting for stronger winds.
- What kinds of activities will take place in or around the tent?
- Are guy ropes and stakes that pose tripping hazards marked adequately, especially during night-time work?
- Emergency disassembly plan: The production should have a plan in place for when tents need to be disassembled for safety reasons (e.g., lightning, rain, wind, weather watch, weather warning, weather alert).
- How stable is the ground where the tent will be assembled? Will it become muddy and saturated during a rainstorm?
- Are there pipes or cables, branches, or other obstacles?
- Where will the tent be set up and what will it be used for? Consider using a site map to identify where you plan to set up tents.
- Can you identify any other potential risks?
Control measures — tent selection, use, and placement
The production should assign at least one person on site who will be provided with a clearly defined set of responsibilities and authority.
When selecting and using large tents, consider the following:
- Consider how the tent will be used (e.g., production, performance, or other purpose)
- How long it will be used for.
- Ensure long structural poles, extendable poles, and other equipment cannot accidentally come within 6 m (20 ft.) of high-voltage power lines during erection or dismantling of tents.
- Ensure tents are properly grounded if they are beneath high-voltage power lines.
- Check with the authority having jurisdiction to find out if a permit is necessary for putting up the tent.
- Marquee, maxi-frame, SaddleSpan, and other tents must have certification tags clearly visible on them that meet the industry standard NFPA 701, CPAI-84, which tent users will recognize as the California Code.
- Check for underground utilities so tent anchor pins won’t contact electrical, gas, or irrigation lines. Have the property host mark underground lines before setup. Note the depth of the lines.
- Check for overhead obstructions such as telephone lines and trees.
- Check weather forecasts. If conditions become severe enough that the tent or temporary structure should not be used as shelter, it must be evacuated immediately. The wind-velocity rating of the structure should be available from the manufacturer.
- Remove snow from the roof regularly.
- Protect metal structures against lightning.
- Evaluate the ground you are placing a tent on (topography). A field will likely be easier to drive stakes into. A parking lot may be harder. Solid, flat ground is generally safer for erecting a tent.
- Follow the manufacturer’s instructions and specifications for anchoring the tent. Some jurisdictions have specific requirements for the anchoring weight that may differ from the manufacturer’s instructions.
- To prevent fires, make sure electrical installations, heating, lighting, and other entertainment equipment are placed and used safely.
- Keep entrances and emergency exits clear of obstructions, and make sure the space between seats is big enough to allow for evacuation.
- Check the tent’s condition. If there are signs of mould or damage, do not use the tent. Return and report it to the owner or rental company so it can be cleaned, repaired, or replaced.
- Encourage proper lifting techniques and ensure two or more workers are involved in assembling, moving, and disassembling tents to mitigate MSI risks.
Remember to add space for specialized activities. For example, if you plan to seat guests at eightfoot banquet tables (eight people per table), plan on 80 sq. ft. per table. Allow additional space for activities such as costume storage, food preparation, or book signings. Consider details such as the location, availability of electricity, and fuelling logistics.
Maximum occupancies for seating
The following table shows suggested maximum seating occupancies for frame tents and pole tents.
Frame tents consist of aluminum or steel pipes and fittings. They’re assembled from the ground up. These freestanding tents do not require any centre poles or stakes.
Pole tents are held up with centre poles and side poles. They’re covered with a top that is held in place with ratchet straps on the outside of the tent. These straps are attached to long stakes that are driven into the ground.
Note: This table is just a guideline. Regardless of what’s specified in the table, building and occupancy codes, bylaws, and regulations will vary for different jurisdictions, and local jurisdictions will override this guideline.
| Tent size | Sq. ft. | Theatre-style seating | Rectangular-table seating |
|---|---|---|---|
| Frame | |||
| 10 × 10 | 100 | ||
| 10 × 15 | 150 | ||
| 10 × 20 | 200 | ||
| 15 × 15 | 225 | 40 | N/A |
| 15 × 20 | 300 | 50 | 28 |
| 20 × 20 | 400 | 80 | 48 |
| 20 × 30 | 600 | 120 | 80 |
| 20 × 45 | 900 | 140 | 96 |
| 20 × 60 | 1200 | 200 | 150 |
| 40 × 40 | 1600 | 320 | 224 |
| 40 × 60 | 2400 | 450 | 344 |
| 40 × 80 | 3200 | 640 | 385 |
| Pole | |||
| 40 × 40 | 1600 | 320 | 224 |
| 40 × 60 | 2400 | 450 | 344 |
| 40 × 80 | 3200 | 640 | 385 |
Heating
In the motion picture industry, the most commonly used types of heaters are electrical, forced air, and direct-fire propane. Whatever heat source you’re using, read and follow the manufacturer’s recommendations at all times.
Electrical
Electrical heaters do not give off any exhaust, so this eliminates the risk of carbon-monoxide poisoning. However, the heaters can be an ignition source if flammables are present.
Forced air with ducting
There are two types of forced-air units in common use. One runs on diesel, propane, liquified natural gas or kerosene, with an electric fan. The unit is placed outside the tent and stack-vented into the air, with ducting that may be run into the tent or building. Direct-fire propane heaters with single and double burners are often used in tents. It is important to ensure that it is safe to have an ignition source inside the tent. Adequate ventilation must be maintained. Two openings directly to the outdoors must be provided, one high and one low, on opposite sides of the area to be heated. Each opening must be at least 7.72 cm (3 in.) for every 1000 BTU. Therefore, for one 50,000 BTU heater, there must be two openings of at least 0.093 m 2 (1 sq. ft.) at each end. The other forced-air unit has a coil that is heated by electricity and an electric fan to blow warmed air where required. The entire unit is sometimes placed directly inside the tent. Depending on the unit, the casing acts as an insulator, and the outside is not hot to the touch. When placing forced air outside a tent, consider the placement of the exhaust to minimize potential entry into the tent.
Direct-fire propane
Direct-fire propane heaters with single and double burners are often used in tents. Ensure that it is safe to have an ignition source inside the tent. Adequate ventilation must be maintained. Two openings directly to the outdoors must be provided, one high and one low, on opposite sides of the area to be heated. Each opening must be at least 7.72 cm (3 in.) for every 1000 BTU. Therefore, for one 50,000 BTU heater, there must be two openings of at least 0.093 m² (1 sq. ft.) at each end.
Control measures — heating
- Workers must be trained in the safe use of all heaters and must follow manufacturer’s instructions.
- Manufacturer’s instructions should be easily accessible for anyone working with or around propane.
- Defective or dysfunctional equipment should be taken out of service and returned to the owner for repair or replacement.
- When setting up portable propane heaters, keep them clear of entrances and exits. Ensure that all flaps are secure or out of the flammable range of the heater.
- Use carbon monoxide detectors in tents where there are direct-fired propane heaters or any combustible operation to help prevent accidental exposure to occupants. Never close the flaps unless there is adequate ventilation from above and below the tent walls. Carbon monoxide is a potentially deadly, colourless, odourless gas that is present in most exhaust. Carbon dioxide is also a product of combustion and respiration.
- When a rental company installs a tent, it is important to inspect all connections, anchor systems, and the positioning of the heaters to ensure they have been installed safely.
- Wall tents sold in Canada must be treated with a fire retardant rated to CPA1-84. Inspect the tents to ensure there is a label indicating the fire-retardant rating. Tents are only fire resistant, not fire proof.
Securing propane
All tanks must be secured to the ground or another stable object. Smaller tanks may be placed inside an empty, square milk carrier to ensure stability. Avoid attaching tanks to the tent. This can be dangerous if it’s windy and the tent collapses or blows away.
Activities in tents
Because of the risk of combustion, direct-fired propane heaters or heaters with electrical elements should not be used in tents where there are other flammable aerosols, combustible gases, or airborne particulates (e.g., hair and makeup, paints, or glues). For tents where flammable products may be in use, consider using forced-air heaters — units in which the ignition sources are outside the tent and warm air is blown in via air ducts.
Aisles
Aisles should be kept clear and made wide enough for safe evacuation in the event of an emergency. Some tents have a strip of material on the bottoms of entrances and exits. These strips can be a tripping hazard. They should be secured, marked, or covered to prevent falls.
Maximum distances:
- Class A fire extinguisher — 22.86 m (75 ft.)
- Class B fire extinguisher — 9.14 m (30 ft.) or 15.24 m (50 ft.), depending on the type of hazard (low, moderate, or high) and the extinguisher rating
Source: NFPA 10, 2010 edition, Table 5.3.1.
Regulatory references
BC Safety Authority regulations require heating appliances to bear a current decal, valid for two years, applied by a gas fitter certifying its safety and operation.
Smoking is prohibited inside tents as per section 4.81 of the Occupational Health and Safety Regulation.The following sections of the OHS Regulation also apply:
- Section 4.2, Safe buildings and structures
- Section 4.3(1), Safe machinery and equipment
- Sections 4.46–4.53, Ergonomics (MSI) requirements
- Section 19.24, Informing workers about high voltage electrical equipment and conductors
- Section 19.24.1, Minimum approach distance when working close to exposed electrical equipment and conductors
- Guideline G13.19, When and how and ground metal scaffold
- Section 20.79, Underground utility services
Fire extinguishers
National Fire Protection Association (NFPA) regulations require tents to have a minimum Class A fire extinguisher available, and a B or C, depending on activities and size. It’s a good idea to have an ABC extinguisher available in tents to ensure that minimums are met, regardless of activities taking place.Maximum distances:
- Class A fire extinguisher — 22.86 m (75 ft.)
- Class B fire extinguisher — 9.14 m (30 ft.) or 15.24 m (50 ft.), depending on the type of hazard (low, moderate, or high) and the extinguisher rating
Source: NFPA 10, 2010 edition, Table 5.3.1.
