How we work out our repair figures

Our advice guides show figures from NAC's own repair jobs: what our engineers found, what fixed it and what it typically cost. This page explains where those figures come from and what each one means.

They currently cover 19,068 jobs across 80 appliance faults , and were last updated on 13 November 2026.

Where the figures come from

Every figure comes from NAC's own jobs, as recorded in our job system: jobs from the last 12 months, updated every night. On every job, the engineer records what they found and what they did, and the figures come only from those records.

A job counts once it's closed, an engineer has attended at least once, and it has been classified (see below). We leave out jobs still waiting to be classified, jobs held for review or ruled out by a person, open jobs, jobs no engineer attended, jobs that weren't repairs (such as installations), appliances outside our lists, and jobs where we can't tell the make.

How faults and causes are classified

Engineers write their notes in their own words, so an AI model reads each job's notes and picks the fault (what was wrong, as you'd describe it), the cause (what our engineer found) and what was done, choosing only from NAC's own lists. Before the model sees a note, names, addresses, phone numbers and other personal details are removed.

We checked the model's answers against a hand-labelled sample of NAC jobs, where a person read the notes and chose the fault and cause themselves.

When the model's answer is uncertain or contradicts itself, the job goes to a person and is left out of the figures until it has been checked. The appliances, faults, brands and causes we publish are approved by NAC first.

What the figures mean

Jobs attended

The jobs for that fault that count, as described above: closed, attended by an engineer at least once, and classified, from the last 12 months.

Confirmed repair

A completed job that we repaired, where 60 days have then passed (after the job was completed, its last update and the engineer's last visit) with no engineer called back to it. If an engineer was called back and the repair on that visit then held for 60 days, it still counts: the repair that worked gives the cause, and the earlier one shows under "often tried first without success". A job where the engineer found it couldn't be repaired or wasn't worth repairing, the customer declined the repair, or no fault was found is a diagnosis, never a repair. This is not a success rate. Jobs inside their 60-day window, jobs still being classified, jobs held for review and visits that didn't end in a repair aren't counted.

Share of our repairs

For each cause, the share of all our confirmed repairs for that fault whose working repair was put down to that cause. "About 1 in 4" is that share rounded to a fraction, and the exact percentage sits next to it. We only list causes with enough repairs behind them, so the shares won't add up to 100%.

Parts fitted

Of a cause's confirmed repairs that didn't need an engineer called back, the share where a part of that kind was fitted.

Often tried first without success

On repairs where an engineer was called back, the first repair that didn't hold and the cause the engineer then found.

Fixed at the first appointment

Of our confirmed repairs, the share fixed in exactly one engineer visit, with no call-back. A repair that needed a part ordered in for a second visit doesn't count. Our engineers carry common parts on the van, so this figure is lower for faults that usually need a part ordered, and it differs from brand to brand.

Typical total paid by customers

The middle half of what customers paid for our confirmed repairs for that fault, in total, parts and labour, including VAT, rounded to whole pounds: a quarter paid less than the lower figure and a quarter paid more than the higher one. We count only repairs customers paid for themselves. Work for manufacturers and insurers is charged at contract rates, so it would make the figure misleading. Each price shows how many repairs it's based on, and a fault without enough customer-paid repairs shows no price. It's a guide, not a quote: your engineer confirms a fixed price before any work starts.

Brand figures

Shown for a brand only when it has enough confirmed repairs of its own for that fault, and a cause within a brand only when at least 25 of that brand's repairs are behind it, the same rule as for all brands.

What we publish, and what we leave out

We only publish a fault once it has at least 30 confirmed repairs and NAC has approved the appliance, the fault and the brand. A cause, or any other share, needs at least 25 repairs behind it, both across all brands and within a brand. Nothing we publish identifies a customer or an engineer.

How often they're updated

Every night. New and changed jobs are read and classified after midnight, and the figures are recalculated by about 4am. A repair only counts once its 60 days have passed and been checked. The pages on this site are updated every night with the new figures, and each set of figures shows the date it was last updated and the most recent job it includes.

Questions about a figure? Get in touch and we'll explain how it was worked out.