Dirty switches, relays and connectors cause intermittent contact, crackle and sparking. With the equipment switched off, clean them with an electrical contact cleaner and let them dry fully before switching back on. Micron 3201 Electrical Contact Cleaner is a solvent cleaner whose page lists all electrical contacts, electro-mechanical and control assemblies, and says it removes dust, dirt, light oils and fingerprints and leaves no residue. For heavy oxidation or flux, Micron 3211 lists removal of oxidation and flux.
Why it happens
- Dust and dirt. Panels and enclosures pull in dust that settles on contacts.
- Oil and fingerprints. Oil mist in workshops and handling during maintenance leave films that insulate contacts.
- Oxidation. Contact surfaces oxidise over time, especially in humid air.
You will see intermittent contact, crackle in switches and controls, sparking at contacts, or visible dirt and oxidation.
How to fix it
Switch off and isolate the equipment first, then choose:
- Light dirt, dust, oil and fingerprints on switches, relays and connectors: Micron 3201 Electrical Contact Cleaner. Its page lists electro-mechanical assemblies, control assemblies, all electrical contacts and sensors.
- Heavy oxidation or flux: Micron 3211 Non Flammable Contact Cleaner, whose page lists removal of oil, grease, flux and oxidation, with relay contacts, switches, terminal blocks and connectors among its uses. Use it with the equipment switched off as well.
- General contact cleaning on machines, where you also want rust protection: Micron M.A.M.A Multi Application Maintenance Aid (4102) lists cleaning and restoring electrical contacts and removing carbon build-up from arcing.
Directions from the 3201 page:
- Spray liberally and allow to run off. Use the extension tube for precise application.
- Use only with adequate ventilation.
- Test before use on sensitive materials.
- Do not use on energised equipment.
- Allow to dry completely before switching back on. Protect and re-lubricate if necessary.
What to avoid
- Do not use 3201 on energised equipment. Isolate the supply first.
- 3201 uses a butane propellant. Keep it away from sparks and flames, ventilate, and let it dry fully before re-energising.
- 3201 is not for sensitive electronic equipment, as stated in its directions. For circuit boards, use a PCB cleaner such as 3400 with the power off.
- Test on sensitive plastics and coatings first; the page says it is safe on most rubbers, plastics and coatings, not all.
When to ask an expert
Call a qualified electrician or replace the part if:
- contacts are burnt, pitted or welded, since cleaning will not fix damage;
- the fault returns quickly after cleaning, which may point to a loose connection, overload or wrong rating;
- the equipment cannot be isolated safely.
FAQ
Can I clean contacts without switching off?
Not with 3201: its directions say do not use on energised equipment. Isolate and lock out the supply, clean, and let it dry before switching on.
Does contact cleaner leave a film?
The 3201 page says it leaves no residue. Its directions also say to protect and re-lubricate if necessary after cleaning, for example on moving switch parts.
Will it damage plastic switch bodies?
The page says it is safe on most rubbers, plastics and coatings and to test on sensitive or stressed materials first.
Is 3201 flammable?
The page states a high-purity butane propellant but does not give a flammability statement. Butane is flammable, so keep it away from sparks, flames and hot surfaces, and use ventilation.
When should I replace a contact instead of cleaning it?
If it is burnt, pitted, welded or worn through, replace it. Cleaning removes dirt and oxidation; it does not restore damaged metal.
See the product: Micron 3201 Electrical Contact Cleaner. Related: 3211 Non Flammable Contact Cleaner, M.A.M.A 4102. More electronics fixes: electronics hub.