“Highly dangerous” devices that claim to help householders save on their energy bills amid the cost of living crisis are for sale online, a charity has warned.  Video footage shows the devices – some for sale on eBay - exploding, risking fire and electric shock, Electrical Safety First said.  Ebay said it took the findings “extremely seriously” and had immediately removed the products from sale.  Electrical Safety First investigated the products after they were brought to the charity’s attention by adverts claiming that they were a way of making savings on energy bills.  The charity bought four of the plug-in devices, which claimed to either save energy or “stabilise electrical current”.