Electrical Safety First (ESF) wants new legislation to close a loophole in the law, which it says allows "substandard and illegal" electrical products to be sold through online marketplaces such as Amazon and eBay.
It comes after an investigation by the charity uncovered items for sale including devices which exploded during testing, potentially lethal phone chargers and extension leads that pose a serious risk of electric shock.
Some of the dodgy devices were being sold on the premise of saving people money on their energy bills, the charity said.
ESF has written to MPs including Jane Stevenson, Stuart Anderson, Valerie Vaz, Shaun Bailey and Pat McFadden urging them to press ministers to bring in "adequate protection" for people buying electrical goods via online marketplaces.
The charity's chief executive, Lesley Rudd, said: "It is imperative that the UK Government holds online marketplaces to the same standard as it holds High Street retailers.
"Gaps in the law allow for opportunistic merchants to take advantage of lax regulations."
ESF investigated gadgets including four plug-in devices, which claimed to either save energy or "stabilise electrical current".
The charity said all four samples failed basic safety standards, risking fires and electric shock, while one device exploded during a test designed to demonstrate its capability to safely handle a short circuit.
EBay said it took the findings "extremely seriously" and had immediately removed the products from sale.
The charity wants a change in the law so online marketplaces have to follow the same safety regulations as other UK retailers, while also ensuring that electrical goods offered for sale on their sites by third party sellers are safe for use.
Under the law, any electrical products reported as unsafe would have to be removed from the site within 24 hours.
An online petition has garnered more than 36,000 signatures.