A NSW company has been fined nearly $1 million over an electrical fault at a regional quarry that led to the death of a woman in her shower.

The 49-year-old's fatal shock at her home was caused by non-compliant electrical work, a lack of critical safety devices and damaged equipment at Cudal Lime Products' nearby limestone quarry outside of Orange in 2014, an investigation found.

The company pleaded guilty to failing to comply with health and safety laws and copped a $900,000 penalty in the NSW District Court on Monday.

The offence is the most serious under the Work Health and Safety Act 2011, with a maximum penalty of $3 million for a company.

NSW Resources Minister Don Harwin said it was the first prosecution of its type in NSW since the introduction of new laws in January 2012.

"This should serve as a warning to all companies and employees, if you don't comply with your obligations you will be held accountable - we make no apologies for that," he said in a statement.

A worker at the quarry was also fined $48,000 for failing to comply with their health and safety duty.

Both parties received a discount for entering early guilty pleas.

The case was brought on by NSW's resources regulator.