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Singed . . . Oamaru Volunteer Fire Brigade deputy chief fire officer Warren Stringer (left) holds a fire-damaged fluorescent light and ceiling panel, and Central and North Otago fire risk management officer Stu Ide shows a fire-damaged fluorescent light ballast box. Several fires caused by the equipment have been reported in Oamaru recently. PHOTO: DANIEL BIRCHFIELD

A series of fluorescent light ballast box fires in Oamaru is concerning the Oamaru Volunteer Fire Brigade, which has advised commercial building owners with the lights installed to be vigilant in checking them.

There have been seven fires in as many months, each at a different commercial premises around Oamaru.

The most recent was at the Oamaru branch of Z Energy on March 2, when a small fire ignited in the service station’s roof space. The petrol station had “minor damage” and was cordoned off and closed for most of the day.

All other reported fires also started in roof spaces.

Fluorescent light ballast boxes contain a transformer and a small capacitor. In some ballasts, both are embedded in pitch, which holds them in place, lowers their operating temperature, and reduces hum.

When heated, the pitch gives off an electrical odour, and if the heating continues, the pitch can liquefy and drip from the light fixture. If heating has progressed to a high enough temperature, the leaking pitch can ignite and drip fire down on to the floor and items stored below.

Central and North Otago fire risk management officer Stu Ide said there were two telltale signs to look out for – a pungent odour coming from a light fixture, and dark brown staining around it.

“It’s telling them something is not right and they should not ignore that. Turn the power off and phone the fire service on 111, or get their electrician in to check it out.”

He said the fire service and some electricians used thermal imaging cameras to determine where the heat source was coming from, as many commercial buildings had several fluorescent lights.

He believed the issue may be a result of ageing lighting systems, or a manufacturing fault.

“Some of the buildings down here are probably getting on in terms of their electrical wiring, so for me it’s about maintenance from the building owner.

“It could be a bad batch .. but we won’t know that until we start picking through and start having a look.”

There were no other recent cases of fires caused by fluorescent light ballast boxes in the Otago region, lending weight to a possible manufacturing defect.

Mr Ide said it was sometimes not possible to determine the manufacturer of the components due to fire damage.

However, at least one fire was caused by an overheating Vossloh-Schwabe brand box.

Oamaru Volunteer Fire Brigade deputy chief fire officer Warren Stringer said there was no need for commercial building owners to panic at this stage.

“It’s something we need to get out and make sure people are aware of it. We don’t want to scare people, but this is happening in Oamaru at the moment.”

He and Mr Ide advised people to turn off all lights at night, with the exception of security lighting, and to get fluorescent lighting systems checked by an electrician.

Energy Safety, part of WorkSafe New Zealand, has been notified.