Electrical Fires Caused by Fluorescent Luminaires Retrofit With Led Tubes

Location: Pitt Meadows, BC

Regulated industry sector: Electrical - Low voltage electrical system (30V to 750V)

Impact

Injury

Injuries: 0

Injury description: None

Injury rating: None

Damage

Damage description: Major damage to two light fixtures and damage to a pallet of stored materials.

Damage rating: Major

Incident rating: Major

Incident Overview

Two separate fires within approximately one week of each other occurred on two linear fluorescent tube style luminaires with electronic ballasts that were retrofitted with 6 Universal brand light emitting diode (LED) tubes each and clear covers in the high ceiling of a storage warehouse.

Investigation Conclusions

Site, system and components

Fluorescent luminaires utilize ballasts which convert line voltage to levels that effectively start and maintain light output for fluorescent tubes. The fixtures from this site employ program start electronic ballasts which are designed to apply power to the fluorescent tube filament first allowing the cathode to preheat and then applying voltage to the lamps to strike an arc. Once started the filament voltage is reduced.

A variety of options have become available to retrofit existing fluorescent luminaires with LED tubes, for this site UL Type A LED tubes were installed:

• (UL Type A) Utilize existing electronic ballasts if compatible
• (UL Type B) Have integral drivers within the tube to connect directly to line voltage
• (UL Type C) Have LED drivers that are separate from the tube

For this site some light fixtures had six Universal retrofit LED’s installed while some light fixtures had six TCP retrofit LED’s installed Manufacturers installation instructions and specifications must be followed to ensure safe operation of retro fit LED tubes. Ballast compatibility charts confirm coordination between specific electronic ballasts and LED tubes. Where compatibility is unknown, the manufacturer should be consulted.

Failure scenario(s)

Overheating due to incompatibility between the existing ballasts and the LED tubes breaking down the electronic components of the LED tube, creating high resistance, heat and fire igniting the LED tubes and clear covers.

Facts and evidence

Figure 1 - Video of light fixture on fire
Figure 2 - LED tube warning labels
- The LED tube specified to consult the manufacturers website for ballast compatibility
Figure 3, 4 – Fluorescent ballasts (4 & 2 tube)
Figure 5, 6, 7 – Ballast compatibility charts
Figure 8 – Light fixture damage
Figure 9, 10 – LED tube damage before and after
Figure 11 – Storage damage
Figure 12 – Example light fixture
-The on-site electrical contractor reported two light fixture fires, the second fire of a similar nature to the one in the video and within 1 week of the above incident date Non-contributing factors: -There were heaters in the area of the luminaires but they were pointed away from the luminaires and as such were unlikely a factor -There was no evidence available of unseated tube terminals on the fixture tombstones so this is not considered a likely contributing factor -There was no evidence available of incorrect wiring

View full facts and evidence

Causes and contributing factors

It is very likely that the LED tubes incompatibility with the existing ballasts was the cause of the fires

Contributing factors:

• The manufacturers' installation instructions and warnings were not followed during installation
• The clear solid covers provided additional fuel to the fire