Lightning detection for mine and construction sites: the options

A lightning stand-down depends on three things: knowing how close the strikes are, when to stop work, and when it is safe to start again. Sites get that information in very different ways, from a supervisor counting thunder to sirens wired across the site. This page compares the main options, Lumen Sites among them, and where each one falls short.

Counting from flash to thunder

The 30/30 rule is the simplest method. If the thunder follows the flash within 30 seconds, the strike was about 10 km away or closer, so stop and get to shelter, then wait 30 minutes after the last thunder before going back out. It costs nothing and everyone can use it.

On a working site it is not enough on its own. Plant noise drowns out distant thunder, thunder usually carries no more than about 15 km even in quiet conditions, and one person counting covers one spot. The lightning distance calculator shows the method and its limits.

Handheld and single-sensor detectors

Portable detectors pick up the radio signal that lightning gives off and estimate how far away the strike was. They need no installation, which suits small crews, exploration camps and people working away from the main site. A single sensor has to estimate distance from the strength of the signal, so its readings are approximate, and each device only tells the person carrying it.

Electric field mills are a different kind of sensor. They measure the electric field overhead and can show a storm becoming electrified before the first nearby strike, which no system that detects strikes can do.

On-site systems with sirens and strobes

Installed systems put a sensor, a lightning data feed or both behind alarms that sound across the site when strikes cross set distances, so nobody has to be watching a screen for the stop call to go out. They are set up with a provider and suit large operations with many people outdoors. DTN, which now runs what was Weatherzone Business, describes its WZBob system as site-wide audible and visual alarms triggered when lightning breaches your proximity thresholds, working with an existing lightning detection service.

Lightning alerting services

Alerting services watch a lightning detection network around each of your sites and warn you when strikes come close, by message, app or on-site alarm depending on the service. In Australia, DTN offers a Weather and Lightning Alerting Solution for mine sites, and MetraWeather offers lightning alerting for mining, which it describes as including customisable messages telling workers what action to take when an alert is issued. Pricing and terms are set by each provider, so ask them directly.

Lumen Sites

Lumen Sites is a web dashboard. It checks the Vaisala global lightning detection network, delivered by Xweather, for strikes within 100 km of each site. A strike inside the warning distance turns the site to Caution and one inside the stop distance to Stop, and the status holds until 30 minutes after the last strike inside that ring, with the all-clear time on screen. Checks run every 5 minutes while storms are forecast or strikes are nearby, and less often when the forecast is settled. The dashboard refreshes every minute, and a map shows each site’s rings and the latest strikes.

Each site also gets thunderstorm risk for every hour of the next 48 hours, so lifts, pours and blasts can be planned around the likely storm window, along with heat stress, gusts, rain and blasting conditions. There is nothing to install, and the price is on the page: A$999 a month for up to 5 sites.

It does not sound sirens or send SMS, email or push alerts. Status is shown on the dashboard, so during storms someone has to be watching it, or it has to be paired with an on-site alarm.

Side by side

Features vary between products and models, so check the details with each provider. “Depends” means it varies from one product to the next.
	Lumen Sites	Counting	Handheld detector	On-site alarm system	Alerting service
Hardware on site	None	None	A device per crew	Alarms, and often a sensor, installed	Depends on the service
Alarm across the site	No: status on the dashboard	No	Only on the device	Yes	Some services
Coverage	Strikes within 100 km of each site	Thunder, about 15 km at best	Around the device	Depends on the sensor or data feed	The provider’s network
Set-up	Minutes in a browser	None	Charge and carry	Installed with the provider	Arranged with the provider
Price shown publicly	A$999 a month for up to 5 sites	Free	Retail price	Ask the provider	Ask the provider
Several sites on one screen	Up to 5 sites	No	No	Depends	Depends
All-clear timer	30 minutes after the last strike inside the ring	Count 30 minutes yourself	Depends on the model	Depends	Depends
Storm outlook ahead	Hourly for the next 48 hours	No	No	Depends	Depends

Questions to ask any provider

Where does the lightning data come from, and how often is it checked for my sites?
How are crews told to stop: siren, radio, SMS, app, or a screen someone has to watch?
Can each area, such as the pit, the plant and a blasting area, have its own stop and warning distances?
How does the all-clear work, and does the clock restart with every strike inside the ring?
What happens when the internet, the power or the provider’s service goes down?
Can we see the strikes on a map, and is there a storm forecast for planning the day?
What does it cost for all of our sites, and what is the minimum term?

When Lumen Sites is not enough

You need an alarm that sounds without anyone watching. Lumen Sites shows status on a dashboard. It does not sound sirens or send SMS, email or push alerts, so pair it with an on-site alarm, or make watching it someone’s job whenever storms are forecast.
Explosives and charged blast patterns. Your explosives procedures may call for warning before the first strike, which a strike network cannot give. An electric field mill on site can show charge building overhead.
Storms the forecast missed. Lightning is checked on a schedule: every 5 minutes while storms are forecast or strikes are nearby, and less often when the forecast is settled. A storm that builds without warning can be picked up late, so sites that must catch the very first strike need on-site detection.
No connection, no dashboard. Lumen Sites needs an internet connection, the lightning data service and its own servers to be running. Keep the 30/30 rule and a manual stop call in your plan as the fallback.
Contract or regulator requirements. If a client standard, contract or regulator specifies detection equipment, Lumen Sites does not replace it.

Using more than one

Sites often combine methods: detection or an alerting service for distance and the all-clear, an alarm or a radio call for the stop, and the 30/30 rule as everyone’s personal backstop. Write each one into your trigger action response plan (TARP), with who watches what and what happens when one of them is unavailable. The lightning TARP template has a table for it.