Two companies charged over a gas explosion in Auckland that killed a worker and caused another to lose his legs will face a two-week defended hearing next year.

Canadian mother-of-two Philomen Gulland, 48, died in the blast in Onehunga on June 4 last year while working for Watercare, an Auckland Council controlled organisation.

Gulland's colleague, engineer Ian Winson, lost both his legs in the explosion and several other workers were injured. 

The Department of Labour confirmed in November last year it was prosecuting Watercare and one of its contractors, Canadian Pacific Ltd.

Watercare and Canadian Pacific Ltd have pleaded not guilty to all charges.

Watercare faces three charges under the Health and Safety in Employment Act and Canadian Pacific faces two.

The charges relate to the duty an employer faces to keep its worker safe and ensure they are not exposed to hazards. If emergencies arise, there must be procedures in place to deal with any incident.

Other charges relate to the employer's duty to make sure that no action, or inaction, by any employee puts any other person at risk.

Lawyers for both parties appeared at the Auckland District Court today and entered not guilty pleas.

The hearing is scheduled to start on September 2 next year.

- © Fairfax NZ News