# Cleaning electrical contacts



## dlane (Mar 18, 2019)

I have a Allen Bradley 3ph push button start switch powering a 220v 1ph compressor, only using two connections.
It’s working good , the contacts look a little dirty/ burnt  though , anyone know a good way of cleaning contacts ?


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## 4ssss (Mar 18, 2019)

Contact cleaner. Radio Shack sells it


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## tq60 (Mar 18, 2019)

Paper...

Cut plain paper into strip same width as contacts.

Place between and lightly push them closed.

Just enough pressure to cause paper to drag just a bit.

Pull paper through slowly.

It will polish off tarnish.

Do not file or sand as the plating may be harmed.

Denatured alcohol cleans well but be sure it is dry.

Sent from my SAMSUNG-SM-G930A using Tapatalk


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## Z2V (Mar 19, 2019)

tq60 said:


> Paper...
> 
> Cut plain paper into strip same width as contacts.
> 
> ...


I agree. Over the years I’ve cleaned literally thousands of contacts with a dollar bill. I might not have a piece of paper with me but always would have a dollar in my pocket.


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## ThinWoodsman (Mar 19, 2019)

4ssss said:


> Contact cleaner. Radio Shack sells it



Good luck finding a Radio Shack!

I've always used rubbing alcohol. Once it evaporates, a quick rub with a paper towel will remove any remaining water.


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## 4ssss (Mar 19, 2019)

ThinWoodsman said:


> Good luck finding a Radio Shack!
> 
> 
> 
> ...


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## hermetic (Mar 19, 2019)

Yes, alcohol is good, but if the contacts have been arcing, there will be metal deposited from one contact to another, you can use a very fine file, or even a nail board to flatten and polish the contacts. they should be left clean, and slightly domed. A thin coat of vaseline helps to damp arcing and allows them to slide over each other to find their closest contact point. Many will say you can't do this, I was taught it as an apprentice electrical engineer, and have done exactly this for over 40 years. It stops arcing, and noisy starters, and is a one time cure!


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## dlane (Mar 19, 2019)

After cleaned what about a little dielectric grease on contacts, or is Vaseline better.


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## Tom1948 (Mar 19, 2019)

I never grease the points themselves. Parts stores have contact cleaner. They should be clean and dry.


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## randyjaco (Mar 19, 2019)

There is a product called Flexstones I have found to be very useful for heavily pitted contacts.




__





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They were originally designed for automotive contacts. A good item to keep in your toolbox if you work on contacts at all. They have been a lifesaver in a few situations for me. They are also very helpful for other abrasive situations in confined spaces.
Randy


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## kd4gij (Mar 19, 2019)

If not pitted  a 100 dollar bill has just abrasives to clean points. I wet it with acetone. If pitted you can't beat flex stones. 




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## Ulma Doctor (Mar 19, 2019)

if you use a *new *or a dedicated fine toothed file, you can dress contacts easily.
i have a file that is used only for contacts.

contact tips can be replaced on a lot of the old AB contactors.
if you can get me the size and model, i may even have a set laying around the house 
if not we can get a set


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## killswitch505 (Mar 20, 2019)

+1 with ulma doctor also with the sand paper. I’m an electrician by trade I use contact cleaner mainly to clean parts not so much contacts once they start welding you have to smooth the contact surface


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## killswitch505 (Mar 20, 2019)

Ulma Doctor said:


> contact tips can be replaced on a lot of the old AB contactors.
> if you can get me the size and model, i may even have a set laying around the house
> if not we can get a set


 It’s crazy how throw away things have become the only gear I replace contacts on are my 2000a switchies. I can damn near buy a whole size 5 starter for the price of just the contacts. I can damn near buy a whole pump panel for the price of a contactor/starter


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## hermetic (Mar 20, 2019)

You are maybe better supplied with spare parts than we are . A lot of the gear I used to service was in good order, and old quality equipment far better than most of the cr*p you buy today, but parts like spare contacts are getting hard to source. Have worked on Allan Bradley, Alan West, and mainly MEM starters, but also remember some of the old Ellison oil filled resistance starters with the all copper sliding contacts. I have always used Vaseline, never used a dielectric grease, but not saying you can't use it, best ask the manufacturers. They definitely arc less when "greased" bot only a smear!!


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## HarryJM (Mar 20, 2019)

You could use an ignition point file (amazon, etc) which is what I used for cleaning motor contact point back when I was a motorcycle mechanic. That and a can on contact cleaner will clean things up.


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## Tozguy (Mar 20, 2019)

I took to using strips of foam backed sandpaper a few years ago and like it. It is available from body shop suppliers in very fine grits like 2000 and 4000. The idea of the foam backing is to imagine the paper forming to the dome shape of the points and providing a light pressure when sandwiched between the points. Whether it does or not is beyond me but after using spray, files, and flex stones over the years, the body shop sandpaper is now my favourite. It allows me to use a fresh piece every time and prevent contamination on the points.


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## fixit (Mar 20, 2019)

CRC makes my go to electrical cleaners. It can be found in most auto parts & hardware stores. Polish contacts with 400 wet/dry paper first, fold a piece 2 or 3 times lift contact, let it close & scrub. Use CRC then blow out to clear residue & dry. OH, BE SURE TO TURN OFF POWER FEED FIRST.


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## kd4gij (Mar 20, 2019)

You can get a cheap point file at Napa.


			https://www.napaonline.com/en/p/BK_7769143


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## pontiac428 (Mar 20, 2019)

For old switches like headlight switches, rotary barrel switches, etc., the coolest way to renew them is to blast with glass beads at medium pressure, and then clean with compressed air (leave the whole part assembled!).  Works amazing, even on plastics, bakelite, painted surfaces.  Sounds aggressive, but is really gentle.  The results are fantastic.  Won't do you any good if the switch is still installed on the machine, though.


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## warrjon (Mar 21, 2019)

Been repairing electronics for a living for 40years my go to is a pencil eraser if I can get it in there, if not very fine wet&dry with alcohol, especially if the contacts are very dirty. If they are pitted new switch/relay.

Don't use valsoline on contacts it is flammable and an arch can cause it go boom.


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## hermetic (Mar 21, 2019)

warrjon said:


> Been repairing electronics for a living for 40years my go to is a pencil eraser if I can get it in there, if not very fine wet&dry with alcohol, especially if the contacts are very dirty. If they are pitted new switch/relay.
> 
> Don't use valsoline on contacts it is flammable and an arch can cause it go boom.


Used Vaseline for 40 years, on all contacts in all types of medium voltage (up to 450V) motor starting and control gear, controlling motors up to 200hp, so Plenty of heat, and plenty of arcing1 No explosins were noted......................


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## hman (Mar 21, 2019)

Don't know much about vaseline or other petroleum based lubes for contacts, but I will offer a cautionary note ...
DO NOT be tempted to use any kind of silicone based lube on contacts.  Silicone oxidizes to silicon dioxide (glass), a very effective insulator.


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## juiceclone (Mar 21, 2019)

hman said:


> Don't know much about vaseline or other petroleum based lubes for contacts, but I will offer a cautionary note ...
> DO NOT be tempted to use any kind of silicone based lube on contacts.  Silicone oxidizes to silicon dioxide (glass), a very effective insulator.


AGREE .... Years ago, when silicone sprays first showed up, we started to have equipment problems. Finally one of the manufacturers reps showed up and told us "never use silicone sprays NEAR any elec contact surfaces .. silicone causes contact failures"


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## warrjon (Mar 28, 2019)

This is why I do not use Vaseline. It will ignite especially if it's thin.

3rd paragraph. All of our equipment comes with instructions not to use Vaseline as it could ignite and cause burns

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3468287/

https://www.patientsafetyinstitute.ca/en/NewsAlerts/Alerts/pages/alertdetail.aspx?alertid=DK05


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## Winegrower (Mar 28, 2019)

My opinion:
1) high current contacts that arc need filing, sanding, polishing, etc.   Not cleaner.
2) low level contacts like signals, sensors, multi-pin connectors, etc. can benefit from cleaner, though I have been unimpressed compared to just mechanically mating and unmating a few times, maybe scrubbing with a pencil eraser.
3) here is a terrific liquid product that has worked remarkably well in restoring old eBay electronics - Stabilant 22.  It’s relatively expensive, but a tiny amount goes a long long way.   Check it out.


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## Blackjackjacques (May 5, 2019)

You should never use a file or anything abrasive on electrical contacts as you will remove any protective coating and damage the polished surface.  If you rough up the contact with anything abrasive you create pits and wind up decreasing the contact-to-contact surface area.  WD 40 contact cleaner is what I use, and for a soiled contact, I use strips of newspaper soaked with the WD40 to burnish the contact and clean.  Once clean and dry, use ElectroLube to wet the contact.


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## hermetic (May 6, 2019)

Blackjackjacques said:


> You should never use a file or anything abrasive on electrical contacts as you will remove any protective coating and damage the polished surface.  If you rough up the contact with anything abrasive you create pits and wind up decreasing the contact-to-contact surface area.  WD 40 contact cleaner is what I use, and for a soiled contact, I use strips of newspaper soaked with the WD40 to burnish the contact and clean.  Once clean and dry, use ElectroLube to wet the contact.


read the post above!, absolutely pointless spraying contact cleaner into a 3 phase star delta starter with burnt contacts!! you get the file out! you have obviously never seen the inside of a large motor starter, what works for electronics is totally useless in heavy electrical engineering!


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## hermetic (May 6, 2019)

We ALWAYS used Vaseline, we never used anything else. I have over 40 years of practical experience of use to back up what I have said. you are just regurgitating what you have been told, hearsay evidence. Vaseline does not catch fire, or explode!!


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## Bi11Hudson (May 7, 2019)

Need to throw my "old school" knowledge in here. It so distresses me to see all this "new fangled" stuff mentioned. [We] had archaic overhead bridge cranes, the control contacts referred to as "street car" controllers. The power contactors were rated NEMA Size 1 up to NEMA Size 5, about the size of a silver dollar. DC, 280 Volt most of it. We occasionally had trouble with AC contacts on motor starters. NEMA Size 1 and smaller. Just replaced the contacts if they were burnt. High voltage stuff mostly had fuse jacks or oil starters. But that for the high horse power 2300 and 4160 volt equipment.

Electricians carried a coarse half round file and a rubber commutator cleaner to dress contacts. Sandpaper was *NEVER* used, it left grains of sand in the copper. And sometimes *conductive* grains if you happened to grab a piece of emery cloth. An Isopropyl based contact cleaner if it was handy. Compressed air otherwise, but watch out for moisture.

For instrumentation contacts and relays, I usually used heavy typewriter paper or a dollar bill. Currency paper is a better abrasive than typewriter paper. In later years(early 80s), I was working on a hard drive at Majuro, in the Marshall Islands. Old style hard drive, by CDC, 18x36x30 inches or so. A 9 platter 18 head back-up drive. Had a faulty motor starter relay. I showed the "system administrator" how to dress the contacts. All I had handy was a US $100 note, traveling money. I told him a $10 would work, just not as well. He took me serious, went looking for a $100 note to *keep in the office*. I laughed all the way to Ponape, my next stop.

A final note, always use an Isopropyl contact cleaner, *never* "Trichloro-*anything*". It will melt plastics. Won't hurt bakelite on old equipment, but will melt even high tech plastics. BTW, Vaseline won't catch fire, but it does attract/hold grit. Not a good move.

Bill Hudson​


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