U.S. media speculate on the cause of the fire in Hawaii: bare conductor, tilted poles

The U.S. island of Maui, Hawaii, ignited a fire on August 8th. As of the evening of the 28th local time, the wildfire has led to at least 115 deaths and caused more than billions of dollars in losses. However, the trigger for such a serious public safety incident may have been caused by the bare conductor of the cable.

CNN quoted Clay Trelawnykster, an assistant expert on tropical fires at the University of Hawaii at Manoa. As saying that this is by far the deadliest wildfire in Hawaii’s history.

What exactly happened? Why is there a claim and possibility that bare conductors caused the fire? Let ZMS’s vericable cable team take a look at the connection between bare conductors and fires.

What is a bare conductor?

Bare conductor cables are products that have only a conductor and no insulation.

This includes round single wires of various metals and composite metals such as copper and aluminum. As well as stranded wires, flexible wires, type wires. And profiles for overhead transmission lines of various constructions.

Use of bare conductor

Bare conductor cable can generally be used as the conductive wire of the cable. In the motor, electrical appliances, transformers, and other equipment as a component.

In addition, the bare wire can be directly in electric power, communications, and transportation. And other sectors, such as the transmission of electrical energy and information.

Bare wire should have good electrical conductivity and physical and mechanical properties.

And bare wire only conductor, no insulation and sheath structure.

Common bare conductor

There are many common bare conductors, such as overhead cables that can be seen everywhere on the street is one of the most popular cable products in bare conductors.

Aerial Cable Bare Conductor

All Aluminum Conductor-AAC

All Aluminum Alloy Conductor-AAAC

Aluminum Conductor Steel-Reinforced-ACSR

As shown in the picture:

Fallen cable causes sudden fire

The Associated Press on the 27th of local time to analyze the possible causes that triggered the fire on the Hawaiian island of Maui.

The news said that the island’s power poles were blown down by strong winds. Resulting in electrified bare wire cables slapped on the hay and sparks, which led to the fire.

Also according to an analysis by the Associated Press, originally most of the island was covered with miles of Hawaiian Electric Company bare conductors. These uninsulated metals can create sparks when they come into contact with the hay.

The AP also says the company’s 60,000 utility poles are mostly wooden, compounding the problem.

Wood products are known to be standard combustibles.

The Importance of Cable Insulation

The main function of cable insulation is to insulate the conductors in a cable from their surroundings or neighboring conductors from each other.

The core of a cable wire is the conductor, and to prevent damage to equipment due to short-circuiting of bare wires. As well as hazards to people from wires exceeding safe voltages a protective layer of insulation (non-conductor) must be added to the cable.

In other words, if the cable is insulated, even if it falls on hay, it will not spark and cause a fire.

Even substandard insulation thickness can affect the cable.

1 Shortening the service life of cables

After the long-term operation, especially in direct burial, water immersion, open-air, or corrosion-prone environments.

Due to the long-term corrosion of the external medium, the insulation level and mechanical level of the thin point of the sheath will be reduced.

2 Increase the difficulty of cable laying

With the development of global industry, more and more environmental requirements of high-voltage cable products, the outer diameter must be small.

The laying process needs to be considered to leave a gap to dissipate the heat generated by the wire and cable energized.

Excessive sheath thickness can make laying more difficult.

Would installing insulated cables have prevented this disaster?

The cable company documents show that the poles were built to “an outdated 1960s standard”.

They were already leaning and nearing the end of their life expectancy.

So much so that the poles fell far short of the U.S. National Standard of 2002.

Overhead Bundled Cable with Insulation

ABC overhead bundled cable is bare wire with insulation.

That means even if the island was covered by overhead insulated cable, would it have prevented this disaster?

Besides, not all scenarios are suitable for overhead bundled cables. Looking at the cost of the added insulation that would be required to have it attached. It would be a lot for companies to consider.

Perhaps there’s another reason

The Associated Press cites a 2019 document that says work to replace old wooden poles is lagging due to other “priorities.”

The document also warns of a “serious public hazard” if the poles are “substandard.”

A former electricity expert at the Worcester Polytechnic Institute in Massachusetts said fully insulated cables were “unlikely” to start fires in dry vegetation.

Hawaiian Electric has said in a statement that it has “long recognized” the “unique threat” posed by climate change. And has spent millions of dollars on it, according to the U.S. media.

However, it did not say whether the wires that collapsed and fell in the early stages of the fire were exposed.

According to previous reports, the local time on the 8th, to the dry and hot weather and Hurricane “Dora”. There are more than 100,000 people in the Hawaiian Islands, the second largest island of Maui outbreak of wildfires spread rapidly.

The U.S. media said that the current official data show that the accident has caused 115 deaths.

According to CNN (CNN) reported that the Hawaii State Maui authorities on the 24th of Hawaii Electric Company and its subsidiaries filed a lawsuit. Alleging that the negligence of the utility company led to the local “devastating” fire.

The above is an analysis of the responsibility of the cable in the Hawaii fire. ZMS cable editorial reminds everyone in the daily life of electricity must pay attention to safety, If necessary, you can choose some fire-resistant cables, flame retardant cables low-smoke halogen-free cables, and so on.