Deal website GrabOne has been fined $40,000 for continuing to sell a bubble machine after being told it gave a woman an electric shock.

GrabOne pleaded guilty in the North Shore District Court to a charge under the Electricity Act of failing to take action while knowing there was a reasonable likelihood of serious harm to any person, and a charge under the Electricity (Safety) Regulations of selling an appliance knowing that, or being reckless as to whether, it was electrically unsafe.

The charges came after Auckland woman Sheree Kennedy purchased a bubble machine through GrabOne. She got an electric shock that threw her backwards when she went to use the machine in December 2013. The machine was plugged in but switched off.

Ms Kennedy had achy arms and chest muscles for days after the shock and complained to both GrabOne and the wholesaler Kmall Ltd. GrabOne asked Ms Kennedy to send back the machine for testing but did not withdraw the product or notify those who had bought it.

Energy Safety intervened and found the bubble machine had no voltage markings, it was not earthed and there was only basic insulation of exposed metal parts.

Following the sentencing, WorkSafe New Zealand spokesman Brett Murray said the bubble machines were “simply unsafe”.

"GrabOne sold 439 of these machines over a relatively short period of time,” Mr Murray said.

The machines were recalled in February this year following the Energy Safety investigation.

"This is the first time an online marketplace has been charged as a party to this type of offending. They are more than just a sales venue and are responsible for the actions of merchants that use them,” Mr Murray said.

GrabOne’s operations director Tracey Moerkerk said in a statement: “We acknowledged from the beginning we got this wrong, which is why we pleaded guilty. While the situation is highly regrettable we are confident we have improved our systems so that this situation would not happen again."

Kmall Limited has pleaded not guilty to selling an unsafe electrical appliance and for failing to take action while knowing that there is a reasonable likelihood of serious harm to any person (charges under section 163C(1) of the Electricity Act). The case has not yet gone to trial.