Very low voltages which would possibly be undetectable by the Volt Stick can still have sufficient energy to trigger a spark and an explosion! http://national-abstract.com/__media__/js/netsoltrademark.php?d=www.maanation.com%2Fpost%2F291409_https-www-google-com-maps-cid-3118858483591648307-the-role-of-gas-engineers-in-r.html