ApprenticeMedium risk

Fluorescent light not starting or flickering

A fluorescent tube won't strike, flickers, or glows only at the ends — common in older garages, laundries, and sheds.

Safety first

Isolate before working on the fitting. Some fittings contain a starter and ballast/capacitor — discharge and care as needed.

Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.

Full detail — causes, the why, and common mistakes.

Likely causes

Ranked from most to least likely.

1
End-of-life tube
Most likely
Blackened ends, flicker, or failure to strike usually means the tube is spent.
2
Faulty starter (switch-start fittings)
#2
A failed starter causes repeated flickering/attempts to strike.
3
Failed ballast
#3
A failed magnetic or electronic ballast stops the tube working.
4
Poor tube contact in the holders
Least likely
A tube not seated properly or corroded holders break the circuit.

Reports are saved on this device to reflect what you actually find.

Testing sequence

Work through one test at a time. Expected reading and what each result means.

Test 1 of 3

Reseat or swap in a known-good tube.

Expected reading

Works with a good, properly-seated tube.

Your actual reading

If it passes

It was the tube/seating — done.

If it fails

Still faulty — check the starter, then the ballast.

Often leads toA single light not working Lights flickering

View all expected readings at once

1. Reseat or swap in a known-good tube.

Works with a good, properly-seated tube.

2. On switch-start fittings, replace the starter and re-test.

Strikes cleanly with a new starter.

3. Isolate and check the holders/contacts and the ballast.

Good contacts and a healthy ballast.

Fault-finding flowchart

The same logic as a decision tree.

1
start
Fluorescent won't start
→ step 2
2
decision
Does a known-good, seated tube work?
Yes→ step 3No→ step 4
3
result
Tube/seating was the cause — done.
4
decision
On switch-start, does a new starter fix it?
Yes→ step 5No→ step 6
5
result
Starter was the cause.
6
decision
Are the holders/contacts and ballast healthy?
Yes→ step 7No→ step 8
7
result
Re-check tube/starter compatibility.
8
result
Failed ballast/holders — repair/replace (or convert to LED).

Common mistakes apprentices make

Replacing the ballast before trying a new tube and starter.
Not checking the tube is seated/making in the holders.
Ignoring blackened tube ends that clearly indicate end of life.
Forgetting switch-start fittings have a replaceable starter.

When to stop & escalate

Ballast replacement and any fitting rewire is licensed electrical work. Many old fluoros are now economically replaced with LED battens — a licensed electrician can advise.

If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.

Related faults

Lighting

A single light not working

One light fitting is dead while the rest of the lights on the circuit work fine — points at the lamp, the fitting, or the switch for that point rather than the whole circuit.

4 causes3 test steps

ApprenticeMedium risk

Lighting

Lights flickering

One or more lights flicker — constantly, intermittently, or when other appliances run. Common with LEDs and dimmers, but can also signal a loose connection.

5 causes3 test steps

QualifiedMedium risk

Outdoor & garden