Can I grease my DMM selector with SILICONE oil?

[001]

Hi!

there are many talks about DMM selector grease
BUT few multimeters aren`t greased anyway 
Can I use SILICONE oil for what purpose?
Is it safe for high voltage (400V AC)?

Thanx

[rsjsouza]

If you intend to use lubricant on the contacts of the rotary switch, there is a discussion about this on Joe's thread (the multimeter safety thread) and, in his experience (and mine as well) the absolute majority of DMM rotary switches do not use any lubricant, including Flukes, Brymens and Keysights. His experiments showed that the absence of lubricant did not affect the durability of the contacts.

[vk6zgo]

Hi!

there are many talks about DMM selector grease
BUT few multimeters aren`t greased anyway 
Can I use SILICONE oil for what purpose?
Is it safe for high voltage (400V AC)?

Thanx

I would advise against it
Many moons ago, a warning came out in ( the then) Telecom Australia, warning against the use of silicone based polishing sprays around exchange relay racks.

Apparently, silicone is a very good insulator, & if it gets between the contacts that should connect, they become open circuit.

[BradC]

Hi!

there are many talks about DMM selector grease
BUT few multimeters aren`t greased anyway 
Can I use SILICONE oil for what purpose?
Is it safe for high voltage (400V AC)?

Thanx

I would advise against it
Many moons ago, a warning came out in ( the then) Telecom Australia, warning against the use of silicone based polishing sprays around exchange relay racks.

Apparently, silicone is a very good insulator, & if it gets between the contacts that should connect, they become open circuit.

Oh it's so much worst than that. When it migrates onto any contacts with the slightest potential to arc it gradually becomes silicon carbide and abrades the contact surfaces.

[GeoffreyF]

Oils move and spread.  You would ruin your multi meter.  I also believe selectors resist movement by design.   Having something potentially flammable and spread around if there were an arc would not end well.

You forgot to ask or possibly think - why?  Purposeless maintenance can lead to failure.

[helius]

The selector switches use a standard click-stop mechanism comprising a spring and ball bearing; the wipers do not resist movement, and lubricating them will not "loosen" them. As the wipers are held under pressure, they will displace any grease from the contact patch; it's the same as using dielectric grease to coat a plug or terminal: the resistance is not any higher than if air was being displaced.
Contrary to other posts, I have seen grease in DMM selectors. Two thoughts: I can't say for certain if it was applied at the factory, as most of my meters we bought used, but regard it as unlikely that previous owners bothered to add it. Second, it is quite likely that grease was applied to the plastic hub as this is where you need to control friction. With use in varying temperature conditions it is possible for grease to migrate and this may cause it to creep onto the wipers.
One possible reason that some manufacturers' DMMs appear to not contain lubricants is that they use more advanced materials. There are such things as self-lubricating plastics, oil-impregnated bearings, and such that could keep the hub turning without resorting to visible grease; and the wipers can be treated with very thin, basically invisible, lubricant films.

PS: with that being said, I don't think adding silicone oil would help. The wipers and pads are plated with hard gold and (with whatever lubrication the factory used) should take millions of cycles to wear through to base metal. If you cleaned the PCB with alcohol after a battery leak etc then replacing the lubrication could make sense, but just as a preventative I wouldn't do it.

[001]

So
I want to protect selector from arc at lamels
Is silicone best isolator than air?

[Fungus]

So
I want to protect selector from arc at lamels
Is silicone best isolator than air?

If you think there might be an arc then grease isn't the answer (and probably won't help).

Change the operating procedure, wear protective gear, get a better meter if necessary.

[joeqsmith]

If you intend to use lubricant on the contacts of the rotary switch, there is a discussion about this on Joe's thread (the multimeter safety thread) and, in his experience (and mine as well) the absolute majority of DMM rotary switches do not use any lubricant, including Flukes, Brymens and Keysights. His experiments showed that the absence of lubricant did not affect the durability of the contacts.

If you feel that dropping a grain of sand onto your foot is a good test for justification on if you require steel toed boots, then sure I could understand you feeling that my thread has something to do with safety.  For the rest of us, we know that the energy levels are far to low to equate anything I show with safety.   Of course I have been saying that for years now.

You are correct about me running across brand new meters with grease.  I've seen it used in some meters from the same brand but not across the board (Not all of their meters have had grease).  Fluke for example.   Of course we are not talking about the ball detent area but the actual switch contacts.  Some of the meters that performed poorly in my transient tests used grease while others that have done very well have had it as well. 

So far the meters that performed the best in my 50,000 cycle life test all had dry contacts.  That doesn't mean that a meter with lubricated contacts could not hold up just as good.  I just don't have any data showing this.   For the transient testing, the meters that performed the best have had both.  Hard to say. 

[001]

...

Can You test silicone vs vaseline grease at kilovolts?

[joeqsmith]

...

Can You test silicone vs vaseline grease at kilovolts?

Can you write a test procedure on what you want done and what your goals are?  Give it some thought.

[001]

Can grease avoid arc at typical lamels space? What voltage for silicone and vaseline?

[coromonadalix]

The only grease i saw in good meter where between the dial and the case, never saw anything on the pcb, even if you use some dieletric insulated grease it may provide a way to arc / spark

Humidity can cause some problems too unless you go for very specialised electrician meters   DONT put anything on the traces pads, be sure to clean them properly with no residue left.

I tried on an Fluke 83 because the damn meter was acting strange, my biggest error.  It was doing worse after that, had to use very specialised cleaners to remove it,  was acting normally after a good clean up.

My other 83 began to do the same thing, a good cleanup restored it fine.

If your stubborn  001   DO IT and see what it will do  and dont go over 300v, if it was good in some ways  we should see meters with grease in them and as i see it its not the case on any meter i have or had in the past, i have all tear them appart.

You can do your own search ?


Finally i work in rf equipment, if we have anything greassy on the pcb, it fuck all the adjustments to some degree, instabilities ... it does some kind of capacitor effects on the tests points loll   etc ... a very good clean up restore stability and effectiveness.

The grease maybe good in DC, but for Ac voltages and rf rejections up to 100khz in most modern meters  i would be curious to see some tests.

And finally any greassy stuff may or will attrack dust ... more problems to come ?

[001]

MASTECH grease his meters inside 

[HKJ]

Some meters are greased on the rotary switch, but I have not kept track of it.
I can be seen on some of my tear-down photos, check Mastech MS8268 and AM-Probe AM510 & AM570 (The front photo of the tracks in large version).

[joeqsmith]

I wonder why anyone would consider Vaseline for this application.  Then again, what ever happened to the HVAC repair person from down under that suggested WD-40?  The key was not to put too much on. 

Can grease avoid arc at typical lamels space? What voltage for silicone and vaseline?

Define "grease" and "typical".   What about temperature, voltage, humidity.....   If you can sort out and document what you would like to see ran and why,  I may be able to try something.  Just keep in mind I do not play around or even have the ability to do anything with high energy levels.   You mention 400VAC and if you are working in CAT III, I assume you are trained and not asking about Vaseline. 

[Fungus]

Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking. 

(and if it stops, how much higher do you need to go to get it to spark again?)

[Fungus]

Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking. 

(and if it stops, how much higher do you need to go to get it to spark again?)

The problem with using it on wiper contacts as a "safety" measure is that it will be moved around by the wipers and might even get wiped away completely after a while (which is why I don't understand that some meters have it at all).

Again: If the OP is trying to prevent arcs then he seems (to me) to be looking in completely the wrong direction. Prevent arcs by using proper equipment/protocol and not have arcs in the first place.

(and if you're on a budget, buy a fluke 101  )

[T3sl4co1l]

Oh it's so much worst than that. When it migrates onto any contacts with the slightest potential to arc it gradually becomes silicon carbide and abrades the contact surfaces.

More likely silicon dioxide -- but no less abrasive compared to the soft metal and plating.

I would recommend contact cleaner, or again just nothing at all.  Clean it once in a while maybe, that's about it.  Maybe more often if you're in a dirty environment (lots of dust), though that's a more general thing, clean the whole board and case say, not just the switch.

If it's a cheap mechanism, not only is it not going to help much, it's not worth spending the ten minutes to open it up and clean it.  When it goes flaky, buy a new one and rest easy.

Tim

[joeqsmith]

Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking. 

(and if it stops, how much higher do you need to go to get it to spark again?)

I could use that same test setup that I used when I was playing with those 4.7M resistors.  Just an uncut board, measure the breakdown, add some room temp Vaseline and see how much higher the breakdown is.  The office is cold enough now that at least that stuff wouldn't turn to a liquid.   

Not sure what it tells you but would only take a few minutes to run.   Want it on video?


https://youtu.be/8Zl2HJ5qo_4

[001]

Simple test: Make a spark gap, put Vaseline on it, see if it stops sparking. 

(and if it stops, how much higher do you need to go to get it to spark again?)

well
what about transformers in oil tanks?

[joeqsmith]

You want to submerse your meter in oil?  I've never thought of that.

[Fungus]

what about transformers in oil tanks?

Not the same as a smear of vaseline on a PCB.

[Zero999]

Grease is generally bad for electrical contacts. When exposed to an arc it burns, releasing more heat, which can keep the arc burning for longer. Incomplete combustion products such as carbon and tar are also bad. Carbon is conductive and reduces the insulation resistance of the contacts and sticky tar can clog moving parts.

I leaned this the hard way when I let grease used to lubricate a motor bearing get into the brushes, which completely ruined the motor because they weren't replaceable and even if they were, the commutator became badly corroded. I wouldn't expect it to be that bad with a rotary switch, but it certainly won't be good.

[joeqsmith]

I ran a test using Vaseline as requested.   I recorded it and will include it as part of my next video.  Should be able to post it yet today.


*****

It's on-line. 

[serggio]

The discussion about contact greases here
Also Molykote Dow Corning® 4 look well.
My Fluke 287 has applied grease under rotary switch from factory

[coromonadalix]

Is it under the dial vs the plastic casing       or      the dial contacts and the pcb traces pads ?

[Fungus]

Is it under the dial vs the plastic casing       or      the dial contacts and the pcb traces pads ?

And so the "grease your contacts - it's way better/safer!" movement starts... 

[joeqsmith]

Someone will eventually ask what the PN# was for that GE product.  See the very last post:
https://www.eevblog.com/forum/repair/multimeter-or-oscilloscope-hv-safe-lubricants/msg914477/#msg914477

And so the "grease your contacts - it's way better/safer!" movement starts... 

This site is loaded with threads about people recommending stuff for the contacts of their handheld meters.  We had WD-40, spit and now we have Vaseline.

[Fungus]

This site is loaded with threads about people recommending stuff for the contacts of their handheld meters.  We had WD-40, spit and now we have Vaseline.

Probably, but this one will add another petroleum based product to the fire.

[joeqsmith]

This site is loaded with threads about people recommending stuff for the contacts of their handheld meters.  We had WD-40, spit and now we have Vaseline.

Probably, but this one will add another petroleum based product to the fire.

Perhaps the most obvious statement I will hear today.

[001]

This site is loaded with threads about people recommending stuff for the contacts of their handheld meters.  We had WD-40, spit and now we have Vaseline.

Probably, but this one will add another petroleum based product to the fire.

Perhaps the most obvious statement I will hear today.

Thank You!
And what about Silicone? Silicone is not a sort of petroleum, isnt it?

[joeqsmith]

https://en.wikipedia.org/wiki/Silicone_grease

[001]

https://en.wikipedia.org/wiki/Silicone_grease

Well
is it fire up like vaseline?

[Gyro]

From joeqsmith's link:

Silicone grease should not be applied to (or next to) any switch contact that might experience arcing, as silicone can convert to silicon carbide under arcing conditions, and accumulation of the silicon carbide can cause the contacts to prematurely fail. (British Telecom had this problem in the 1970s when silicone Symel® sleeving was used in telephone exchanges. Vapor from the sleeving migrated to relay contacts and the resultant silicon carbide caused intermittent connection

...as was pointed out earlier in the thread.

Flamability becomes irrelevant.

[helius]

When used properly, a DMM should not have any arcing on its switch contacts—you are not supposed to turn the switch while it is connected to an energized circuit. People do it anyway; for example if there is a separate switch position for ACV and DCV, many users switch between them without disconnecting the meter. Correct operation, not the slathering of lubricant, is the way to avoid switch arcing.

[Fungus]

What about olive oil? Or sunflower? I've got some of that.

[001]

What about olive oil? Or sunflower? I've got some of that.

I tryed sunflower oil many ears ago. it is fail. It came muddy and viscous like glue

[Gyro]

I tryed sunflower oil many ears ago. it is fail. It came muddy and viscous like glue

 

Also, that's what happens when you set your country flag to Antarctica.

[001]

Can I try some pinguin oil? 

[Gyro]

Try Troll juice!

[ch_scr]

Tangentally related: I had a Mastech M9803R that would give unstable high-ohm readings. Like jumping between 8-12Meg with nothing connected. After taking it apart, I also checked the rotary selection switch. There was a clear, sticky substance found and subsequently removed with IPA. Afterwards meter worked flawlessly again. Construction of casing should prevent ingress to that area and no intrusion witness marks were found. No inside source was apparent as well. Thus I suspected it might have been there since assembly. Meter worked well for a few years, not so sure how the sudden change came about. (Thinking about it, maybe it was slowly spread out by actuating the switch, thus taking time to effect the readings?). Take note it was not spread around over the whole switch, more localised like something dripped on. I oiled the switch axle, but left the contacts alone after cleaning.

[coromonadalix]

001  why do you still insist to put oil, grease  etc etc ...

[BradC]

Someone will eventually ask what the PN# was for that GE product.  See the very last post:
https://www.eevblog.com/forum/repair/multimeter-or-oscilloscope-hv-safe-lubricants/msg914477/#msg914477

Interesting. Very sparse info available on line for that particular product. It  seems to have a lot better high temperature stability than the other dielectric greases (or food grade silicone greases) I have around here.

[joeqsmith]

Someone will eventually ask what the PN# was for that GE product.  See the very last post:
https://www.eevblog.com/forum/repair/multimeter-or-oscilloscope-hv-safe-lubricants/msg914477/#msg914477

Interesting. Very sparse info available on line for that particular product. It  seems to have a lot better high temperature stability than the other dielectric greases (or food grade silicone greases) I have around here.

That tube is more than 35 years old now but still pretty decent stuff.   I had looked at what Dow offers.  You may want to check their product line.   I continue to use MSD spark guard on my ignition parts which also seems to hold up well with higher temperatures. 

[001]

001  why do you still insist to put oil, grease  etc etc ...

I saw few video owerviews  about dmms
If no grease at lamels all autors says what it is "chinese cupidity" and adds a lot of grease

[joeqsmith]

001  why do you still insist to put oil, grease  etc etc ...

I saw few video owerviews  about dmms
If no grease at lamels all autors says what it is "chinese cupidity" and adds a lot of grease

Post the links for these videos.  They sound entertaining.

[001]

001  why do you still insist to put oil, grease  etc etc ...

I saw few video owerviews  about dmms
If no grease at lamels all autors says what it is "chinese cupidity" and adds a lot of grease

Post the links for these videos.  They sound entertaining.

It is hard to look out all of them
But easy to google new


  - WTF?

[coromonadalix]

Anyways  I wont argue with 001 

I will never grease the pcb traces with any dielectric grease or what ever you may end with,  I have flukes 189-187 and Gossen meters they have build it that way and they stay that way, they are classified as old meters and do still work perfectly. I dont recall Sanwa doing it, nor Brymen, Fluke, Gossen, Keysight, Thongui ? even in bench meters who have front rear slide switch on pcb's ?

Simply clean and decontaminate the pcb for any residues, dust  etc...  You may add some non petroleum grease (some grease will dry /crack or deteriorate plastics) for the dial vs the casing, but a smal drip thats all i do.

Some good meters brand are made with ''chinese stupidity'' and they have never failed ??

@001  do it if you want for yourself and play with your security or the meter security, i have talked yesterdays with master electricians, they dont ever recommend to do something like that, they call it "sloppy job" ?  They work in 640v panels, as they add more ventilation in our company.

They do use Intrinsically safe meters : i saw a fluke 28 II and a beautiful red Fluke 87v. droll  loll  love the "RED"

[Gyro]

I can't see anything relevant to applying grease to DMM selector switches in any of those videos. 

They keep changing, but...

- The first is a guy changing fuses on a meter
- Is second a comparison of cheap meters
- The third is a guy cleaning muck off the yellow holster of a working Fluke 177 so he can sell it on ebay
- The fourth is a guy slapping excess grease all over the plastics of a Brymen meter so he can get that "quality potentiometer feel" - knob and case in isolation, no detents or contacts. 
- The fifth is a meter comparison, where he does smear some vaseline on a spade connector when measuring its resistance (2 wire)
- The Last is using anti-corrosion / dielectric grease to protect crimps and connectors in an industrial / automotive environment.

Don't waste your time, we're being trolled!


EDIT: I think the links have stabilized now!

[joeqsmith]

Don't waste your time, we're being trolled!

Yep. 

[coromonadalix]

yep +1

[Trader]

... experiments showed that the absence of lubricant did not affect the durability of the contacts.

My RM303 was reading ~1.5 Ohms with shorted probes, after rotating the selector a couple of times decreased to ~0.1 Ohms.  I opened it and see a grease/vaseline in the PCB traces, after cleaning with isopropyl alcohol solved the problem, now is ~0.07 Ohms always.

ps: I also found recommendations to use "Silicone Dielectric Grease", but  I think this insulation property is the culprit for the extra +1.5 Ohms.

[helius]

I'm not too sure you have improved the accuracy. Most DMM leads have ~0.5 ohm each and the contact itself is rather small.
Did you use an actual shorting bar across the + and COM sockets, or just touch the probes together? Only the first is going to be ~0 ohms.

[Trader]

"touch the probes together". Each probe has 0.03 Ohms (in a 4-wire measure).

Before cleaning was always around 1.5R and now ~0.07R.

Yes, I know the accuracy is not good for low ohms, but I measured exactly 1.00R (a 1 Ohm resistor).

[helius]

There is a wide variation in lead resistance, even with quality brands. Using the Fluke 8060A, I measured from 0.07 ohms to 3.50 ohms (!) on a half dozen pairs of probes. The 3.50 leads were echt Fluke, and the lowest was a set that came with an HP-Yokogawa meter.

Interesting that your DMMs were so heavily greased. Silicone dielectric grease is most commonly used for contacts that are exposed to the weather, for example, spark plug wires or lamp bulbs/sockets in wet or outside locations. It works very well to prevent the contacts from corroding together and becoming hard to remove. It also has applications to prevent flashover in medium-voltage circuits, although the DMM itself should be designed to safely absorb such events. I think if I had to restore any lubrication in the switch wipers, I would use a very small amount of contact enhancing oil, not grease.

[Trader]

There is a wide variation in lead resistance, even with quality brands. Using the Fluke 8060A, I measured from 0.07 ohms to 3.50 ohms (!) on a half dozen pairs of probes. The 3.50 leads were echt Fluke, and the lowest was a set that came with an HP-Yokogawa meter.

Yes, same thing here, I have a lot of multimeter probes, I tested each one and I kept only the best ones, around 0.025 Ohms.

Interesting that your DMMs were so heavily greased. Silicone dielectric grease is most commonly used for contacts that are exposed to the weather, for example, spark plug wires or lamp bulbs/sockets in wet or outside locations. It works very well to prevent the contacts from corroding together and becoming hard to remove. It also has applications to prevent flashover in medium-voltage circuits, although the DMM itself should be designed to safely absorb such events. I think if I had to restore any lubrication in the switch wipers, I would use a very small amount of contact enhancing oil, not grease.

This site shows some DMMs teardowns, look at the Aneng AN870 PCB, they also use grease/vaseline.  Seems the high-end DMMs don't use that.

https://lygte-info.dk/pic/Aneng/AN870/DSC_7499a.jpg

[nukie]

Your dmm has a high impedance input in the megaohm range, if your grease conducts then it would mess up the sensitivity and also introduce errors in the measurements.

I say leave the dmm  dial in the setting you use most often and let the autooff do its job. This way you can prevent wear in expense of battery life. You have Eneloop right?

If you are switching the dial too often consider getting a second dmm for the second most used mode. You can never have enough dmm.

[helius]

The lowest resistance is not necessarily the "best" for all purposes. Some of the probes may be designed for lower reactance at the expense of having a couple of ohms that need nulling out at low ranges.