A worker who tried to buy a guitar from his company's second-hand shop who was fired for serious misconduct has been awarded $21,700 for unfair dismissal.

Peter Grierson started working for Metallic Sweeping Limited in March 2017, as an assistant manager at its Marlborough site,  an Employment Relations Authority (ERA) ruling said.

He was fired on June 14, 2018 over a breakdown of trust, after asking a colleague multiple times to un-list a second-hand guitar from Trade Me that already had bids and sell it to him privately.

Metallic Sweeping is a waste management and minimisation company in Blenheim that also has a second-hand "re-use" store.

Metallic Sweeping managing director Clive Peter told the ERA Grierson's actions amounted to serious misconduct and put the company in disrepute.

During his employment Grierson raised concerns about working long hours several times.

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He worked six-days-a-week and worked 60 hours per week, regularly working more than ten hours a day.

Grierson also worked 20 days straight without a single day off.

When he asked to be paid more for working more than 50 hours a week, Peter said he knew going into the job it was a seven day operation.

Grierson's salary was $55,000 per annum with a monthly bonus of $500 based on performance.

Metallic Sweeping said Grierson's pay "more than compensated" for the extra hours he worked.

Grierson also raised concerns about not getting paid when he took sick leave, and said did not receive bonus payments as the KPI's were never finalised.

In May, instead of responding to Grierson's concerns on his terms and conditions, Peter suspended him based on allegations of serious misconduct.

The allegations related to multiple enquiries from Grierson to a colleague about whether he could buy a guitar the company had listed on Trade Me that already had bids.

Metallic Sweeping alleged Grierson breached confidence by discussing the issues around the terms of his contract with colleagues, and a destruction of trust.

The company's investigation found Grierson encouraged a staff member to breach company policy on second-hand goods. And when his colleague refused, Grierson persisted which brought the company into disrepute.

But the authority found Metallic Sweeping failed to clearly outline the rules Grierson had breached as these had not been written anywhere. It was unfair to conclude him asking to buy the guitar amounted to serious misconduct, it said.

"There were no rules about an auction that were disclosed to either Mr Grierson or the Authority. Trade Me terms and conditions provided to the Authority at the investigation meeting did not seem to support that it was not possible to withdraw a listing provided it was not in the last hour of an auction," the authority said.

On the claim there was a breakdown in trust and confidence after Grierson discussed the concerns with his hours and contract, the authority said those conversations were private. A fair and reasonable employer would not have concluded the effect of this resulted in a summary dismissal.

Grierson said he felt hurt and humiliated by his dismissal. Grierson had also shifted from Auckland to Blenheim to take up the role with Metallic Sweeping with the intention of making the most of his new job.

The authority said the issues about serious misconduct were never resolved before Grierson was dismissed.

As a result Metallic Sweeping was ordered to pay Grierson $19,800 in compensation and $1973 in lost wages.