Do you guys use an isolation transformer for your lab/workbench?

[bigfoot22]

deleted

[tooki]

Let’s put it this way: if you don’t thoroughly understand why and when you’d want an isolation transformer, and what it does and doesn’t protect you from, then you shouldn’t work on mains-powered stuff yet, specifically, things with a live chassis.

If you get one, make sure you don’t let it lull you into a sense of false security, such that you actually let your guard down around mains voltages.

As for the specific question of using one to isolate all of your test equipment: an emphatic no!!!!

If you want to add safety to your bench, install a sensitive GFCI (more sensitive than the one your home may already have installed).

[bdunham7]

Just asking because I'm fitting out my workbench and wondered if I shouldn't isolate all of the equipment from the mains with the aid of an isolation transformer then do noise filtering on it.

Why no grounding on isolation transformers?

There's probably not a good reason to do so and most test equipment will isolate their innards from the mains anyway via the power supply transformer or whatever.  Y-cap leakage can still be an issue in some cases though.

Isolation transformers typically pass through the ground connection but that is a separate issue.  You typically would not want to break that ground, certainly not by default.

[AVGresponding]

Let’s put it this way: if you don’t thoroughly understand why and when you’d want an isolation transformer, and what it does and doesn’t protect you from, then you shouldn’t work on mains-powered stuff yet, specifically, things with a live chassis.

If you get one, make sure you don’t let it lull you into a sense of false security, such that you actually let your guard down around mains voltages.

As for the specific question of using one to isolate all of your test equipment: an emphatic no!!!!

If you want to add safety to your bench, install a sensitive GFCI (more sensitive than the one your home may already have installed).

This  ^  100%

Simple quotepost because it bears repeating.

[AVGresponding]

I don't know how things go in the US, but here in the UK, that would NOT MEET electrical safety standards, and would be technically be illegal to sell.

@bigfoot22 sorry, forgot you're an Aussie. I can't imagine it would pass safety regs there either.

[bdunham7]

Not for this one apparently:
https://www.ebay.com.au/itm/254536293226

You don't want that for powering your bench unless you plan on modifying it with a ground somewhere.  It might be appropriate for powering a DUT in certain cases, but I don't like the fact that it has an earth socket that isn't connected to anything.  If there was a device to measure the voltage at that isolated earth socket to actual earth and disconnect the power if that potential rises above SELV voltage, then it might be acceptable. 

[AVGresponding]

Primarily the reason it's non-compliant is that it has the capability to plug in a class 1 (requires an earth connection) device, without having the required earth connection. If it had 2-pin outlets it would comply.

[nightfire]

As a proud owner of an old isolation transformer of the 70ies- has anyone some hint of the actual IEC (Or VDE/german) standard revision for those?

[TimFox]

An electrostatic shield between windings greatly reduces capacitive coupling of high-frequency common-mode garbage (on line and neutral) to the secondary, and such a transformer usually connects the PE ground to the output.
Topaz transformers used to be popular in critical laboratory applications, and can be found at surplus vendors and eBay, but seem to be hard to locate since Schneider bought SquareD. 
They look nice and have very low primary-secondary capacitance.
Here are some at a large US surplus vendor:  https://www.surplussales.com/class/inductor/isolation_1k-4k.html
I couldn't find anything Googling for Schneider Topaz.

[Gregg]

I have a medical grade toroidal isolation transformer dual voltage windings primary and secondary and an electrostatic shield that I rewired the secondary so that I can easily disconnect the output receptacle from the input mains ground via a jumper link on the front where it is readily visible as to the ground status.  This also allows connecting a jumper to an ammeter etc in the ground circuit or to connect to an isolated ground. The ground binding posts are connected to 4mm banana jacks on the side of the case.
I also installed a switch type circuit breaker and 4mm banana jacks on the output. 
It has come in handy in a few cases but it certainly doesn't reside on the bench top.

[nctnico]

Yeah I have no intentions of using it for my lab/workbench after reading your helpful replies. If it doesn't pass through earth then its dangerous anyway. I'll get an RCD/GFCI for my setup.

And get CAT rated high voltage differential probes. These are very affordable (from MicSig for example) and will provide safety while measuring in mains powered circuits.

Also think long and hard if you even need to provide mains power to a mains powered device. Switching power supplies always have a low voltage supply in the primary side. If you use a bench power supply to power the primary side (and a different channel to apply some power to the secondary side) you can test 99.9% of a power supply without even connecting it to mains.

[NiHaoMike]

I have one that does about 100W, made by taking apart two halogen lamp transformers and reassembling one with two primary windings. I use it more for the current limiting although the isolation is definitely a plus.

For more power, I run a 1000W power inverter from a surplus 1400W server PSU. It's rare that I have to do that, even working on fairly large PSUs the 100W isolation transformer is sufficient to see if it at least powers up correctly.

[Electro Detective]

Study isolation transformers in detail till you understand what type for what task,

how to test the actual level of input to output 'isolation', chassis relations,

and that it will do the task before using it,

but not before understanding the source of the incoming power from your mains switchboard first, the earth bond/grounding thing etc


It's actually SUPER SIMPLE even using generic isolation transformers once you have understood the above,

with the wiring option of various degrees of 'isolation' from the mains and or connected suspect equipment etc


My rig has the option of any type of isolation needed,
regulated, varied or limited AC, 
and options to use GFCI or RCD,
and be able to externally test trip them also to ensure they actually do work


i.e. If risky business    I simulate the snafu first, then hook up and power up

and there's a UPS rig too but that's another story as to how it's transformer works on backup disconnected from the mains


My intentions when learning about this stuff were really to be personally 'isolated' from hospital beds
and or a one time permanent earth/ground connection, after a few good overconfident idiot zaps and walkaways over the years. 

'Isolation' has way too many variables for people unfamiliar with all the voodoo and confusion,
to either zap their equipment and themselves,
or cop spark shrapnel in the eyes,

or worse still, send panic'd kitty and fido packing down the street 
into an oncoming beer swilling, bad hair day, 'friday tradie' ute, with cranked up mindless detuned metal mayhem trash. 

Isolation: No research? = No Do ! 

[Brumby]

Let’s put it this way: if you don’t thoroughly understand why and when you’d want an isolation transformer, and what it does and doesn’t protect you from, then you shouldn’t work on mains-powered stuff yet, specifically, things with a live chassis.

If you get one, make sure you don’t let it lull you into a sense of false security, such that you actually let your guard down around mains voltages.

As for the specific question of using one to isolate all of your test equipment: an emphatic no!!!!

If you want to add safety to your bench, install a sensitive GFCI (more sensitive than the one your home may already have installed).

This  ^  100%

Simple quotepost because it bears repeating.

I was going to do exactly the same - for the same reason.

[rstofer]

If you want to add safety to your bench, install a sensitive GFCI (more sensitive than the one your home may already have installed).

In the US, UL standard 943 covers GFCI devices and they trip at 4 to 6 mA of ground current.  I don't think you will find anything more sensitive.  These are used for individual branch circuits, we do not trip the panel main breaker with a GFCI nor do we use something like the UK RCD device.  Typical ratings are for 125/250V up to 50A

It is my understanding (from a quick read on Google) that UK RCD devices trip at 18..23 mA (30 mA max).

[tooki]

If you want to add safety to your bench, install a sensitive GFCI (more sensitive than the one your home may already have installed).

In the US, UL standard 943 covers GFCI devices and they trip at 4 to 6 mA of ground current.  I don't think you will find anything more sensitive.  These are used for individual branch circuits, we do not trip the panel main breaker with a GFCI nor do we use something like the UK RCD device.  Typical ratings are for 125/250V up to 50A

It is my understanding (from a quick read on Google) that UK RCD devices trip at 18..23 mA (30 mA max).

The US is a bit of an anomaly in this regard, in that it uses very low current GFCIs. Elsewhere in the world, 30mA is typical. At my previous job (vocational training center) here in Switzerland, they have 10mA GFCIs protecting each workbench, both so they trip sooner if there’s a fault, and so that it won’t take out the entire lab if there is.

[Infraviolet]

I've heard they can be useful for some forms of high (mains) voltage work, haven't really looked in to the accuracy of such rumours or reasons behind them, but for lower voltage stuff I'd expect they could be a practical menace. Lets put it this way, the things you're designing are probably going to end up being battery powered or run from wall wart supplies, either being imperfect. If you get used to producing designs in a "perfected" environment where everything is isolated from the ground to avoid some particular sort of noise then things you design might then not work in the real world where that noise is present and the isolation isn't.

That said, a lot of low voltage stuff will be isolated anyway, low voltage wall warts are floating and ungrounded relative to mains. And bench power supplies often have a phsyically grounded pin socket on them, but unless you use it the supplies will be floating relative to mains.

[timeandfrequency]

Hi bigfoot22,

tooki's first post sincerely provides you with good advice.

When I have to probe into a device (DUT) with mains/live exposed parts (like boards with in situ SMPS), I do not use an isolation transformer (even if I've got one).
My DUT is powered via a 10mA RCD/GFCI (trips at about 6-8 mA) and the sole allowed TE are first tier (bench) multimeters with IEC1010 compliant accessories, and a truly isolated oscilloscope (Scopemeter) with adequate fully isolated probes.

You may also check out these test leads with selectable safety category and double-insulated silicon wire.  Same stuff but with banana connexion.
Another set from Pomona.

If the DUT has a metallic enclosure, I always use a strong alligator clip to make an additional link from chassis to earth.
Even if it's not practical, wearing class 00 or class 0 insulated gloves provides an additional level of safety.

[tautech]

Hi bigfoot22,

tooki's first post sincerely provides you with good advice.

When I have to probe into a device (DUT) with mains/live exposed parts (like boards with in situ SMPS), I do not use an isolation transformer (even if I've got one).
My DUT is powered via a 10mA RCD/GFCI and the sole allowed TE are first tier (bench) multimeters, and a truly isolated oscilloscope (Scopemeter) with adequate fully isolated probes.

If the DUT has a metallic enclosure, I always use a strong alligator clip to make an additional link from chassis to earth.
Even if it's not practical, wearing /]class 00 or class 0 insulated gloves provides an additional level of safety.

Gloves implies 2 hands are used which for mains breaks the good old rule of keeping one hand in the back pocket when working on mains.

[nctnico]

Has anyone mentioned not to wear jewelry?

[timeandfrequency]

[...]

Gloves implies 2 hands are used which for mains breaks the good old rule of keeping one hand in the back pocket when working on mains.

The well-known rule is undoubtfully good advice when working with bare hands. If you need both hands to probe inside a DUT, wearing insulated gloves usually provides a sufficient level of safety. I couldn't find any seller that only sells one glove.

[tautech]

I couldn't find any seller that only sells one glove.

[themadhippy]

I couldn't find any seller that only sells one glove

Ya didny look very hard,although buying a pair might be cheaper
https://www.smoothradio.com/artists/michael-jackson/white-glove-sold-auction-value/

[Electro Detective]

I couldn't find any seller that only sells one glove.

Bob has you covered:     www.bobthewelder.com.au/products/xt-left-handed-welding-gloves-green-long

---------------------

FWIW folks: 30ma RCDs rarely trip at 30ma

Anywhere from 15 to 28ma  is what usually happens, and a good unit will have about 2 to 3ma repeatability

i.e. test the suckers properly before trusting your life and gear with them,
better still, use two RCDs  piggy backed.
One of the two 'may' trip 'faster', or both will work if the trip current approaches zap city.

But they won't do you much good with an electrical fault or short in the chain, so..FUSE UP, just past the DUTs current rating,

and you won't need an imitation rabbits foot or garlic necklace 

[Electro Detective]

Welding gloves would be too thick I'm afraid.

I already use Nitrile gloves. A highly coveted stockpile of exactly 1 box of them. Got no idea where I'm going to get the second box from but that is a problem for the future.

Once your hands get sweaty in those, you better think of possible conductivity consequences,
especially if there's a pinhole or paper cut slice you can't see, especially if salt is a favorite in your diet. 

I usually have cheap thin cotton gloves on first, then work large nitrile or similar gloves over. You get a few good dry hours use from that.

Or if it has to be tight thin nitriles for finicky handling, then I swap them over for dry ones once I feel the hands getting sweaty

The sweaty gloves get 'flipped out' and put out to dry etc

= a bit hard to put on again, but the effort is great for the wallet 

[AVGresponding]

I couldn't find any seller that only sells one glove.

Bob has you covered:     www.bobthewelder.com.au/products/xt-left-handed-welding-gloves-green-long

---------------------

FWIW folks: 30ma RCDs rarely trip at 30ma

Anywhere from 15 to 28ma  is what usually happens, and a good unit will have about 2 to 3ma repeatability

i.e. test the suckers properly before trusting your life and gear with them,
better still, use two RCDs  piggy backed.
One of the two 'may' trip 'faster', or both will work if the trip current approaches zap city.

But they won't do you much good with an electrical fault or short in the chain, so..FUSE UP, just past the DUTs current rating,

and you won't need an imitation rabbits foot or garlic necklace 

Yes, unlike fuse or circuit breaker ratings, the RCD trip current is the maximum allowable for it to meet its standards.

This is a pretty good source of info on RCDs:  https://www.eaton.com/content/dam/eaton/products/electrical-circuit-protection/circuit-breakers/xeffect-rccb/eaton-rcd-application-guide-br019003en-en-us.pdf

[nightfire]

While we are getting into the topic of RCD:

a) They usually trip in between 0,5*rated diff. current and 1*rated diff.current. Usually manufacturers try to adjust the ti the middle of that range when they are new, so usually those RCD trip between 20-25mA for a 30 mA standard type.
b) When relying on RCD protection: Which waveforms do you expect? If it is not sine wave, the standard RCD type A would not do much...
German manufacturer Doepke has very good material there, called "Allstrom Fibel", downloadable as pdf. Also some general notes on RCD and stuff.
(www.doepke.de)

[themadhippy]

Out of curiosity do the rules for GFCI in the states stipulate a disconnection time,ive had a quick google but find conflicting advice,the only thing  that made sense was T = (20/I)1.43  , but this seems to give  longer times than permitted in the uk,so whilst ours have a higher current before operation it appears ours must operate  faster

[nightfire]

In germany, the corresponding standards mandate a maximum of 0.3s, the low voltage regulations ((up to 1000V) mandate 0.2s above 230V- in reality a fresh RCD in mains installation is tripping faster than 30ms- older models can take a bit longer, in some cases due to old grease in them. This is also the reason why those RCD should be actuated in regular intervals, to prevent grease hardening etc.

[wilhe_jo]

Just a thing to consider...

Even at some none budget suppliers website, a differential probe is at 200.-
I got my vintage Tektronix ones very well below this...
Migsig ones are below 100.-

Do you really want to risk touching life mains, or do you want to risk mains/Gnd short just because it always was like this?

I had quite a enlightening event with a client (10B/a revenue!) some years ago.
When I arrived, I was taken too seriously, because I got there with dated stuff.... Yeahh... Ok..I sell knowledge not decoration ...

Then they got their measurement rig up....

Probing with two brand new Lecroy HD Scopes and 2 isolation transformers (also fresh from the egg).... Perfect.

Effectively they had 2 usable channels per scope.
And using the touch screen is out on the intentional use....
Yeahh. That's the way I want to work!

They were frightened about frying the touch... So we had to shutdown power for every interaction with the scope....

Really, get diff-probes!

2x diff probes
1 current probe

That's what you want to have for single phase!

Just to be clear: my 3 phase dif-probes and my 3 phase current probes were around the price of the 2 premium iso-transformers.

Apart from this, a RCD protects you from things, somebody clever hasn't thought about (or is really, really, really unlikely).
Debating whether ab RCD is an appropriate safety measure to protect you from common mistakes is ... brave.

Work as if you were drunk!
Honestly. That's pretty much what happens in accidents due to laziness or distraction.

Diff-probes keeps the RCD on your side.
An Iso transformer makes the 10+A breaker your only friend!

Oh, yes I work with isolation transformers... A LISN needs that... But you can reduce the pain...

73

[nightfire]

I have some diff probes on my shopping list, but even micsig are 200+ Euros here in germany- do you have any hints where to buy used gear that is not worn down?

Regarding RCD: Yes, they are very useful, so they should be included in every setup on a work bench, but in case you really need then and they do the things they are intended to do, you also get zapped- at least a little bit.
Therefore I would regard them as one of the multiple pieces you (or the one setting up a bench) should consider as part of safety measures.

Which means, that the person doing the setup is responsible for this, and has to think beforehand if a safety/isolation transformer in front of the DUT will and can improve the safety, or simply be a cause of different issues.
In the same league I would sort:
- gloves
- isolated bench
- isolated tools
- diff probes
- lightbulb inrush current limiter
- RCDs (including type B for pulsed or DC currents)

[Electro Detective]

Whatever 'isolation' strategy used, don't forget protective eyewear, it's one - oops! arghhh!!! ****! -     you can't easily walk away from

How many times do people stick their face into a project or repair    filled with with pop-able capacitive parts and solder fumes etc


FWIW, there is NO way I would rely on one 'worked fine yesterday..' RCD or GFCI to bail me out of a situation involving voltage surfing

especially if not externally trip tested immediately beforehand rather than the onboard TEST switch

Have come across a few faulty mains switchboard units that tripped fine with the onboard TEST monthly 'good luck' switch,
that NO ONE on this Earth ever tests, remembers, or even knows about..

but same RCD big fail when pumped externally or at the domestic power point receptacle with 30ma and beyond. 


Another factor many may have not considered is using smaller, fast fuse input and delayed fuse output, isolation transformers,
that just meet the current draw requirements of the DUT
This way you at least are not copping the full output of the street transformer through the shorted gear or shorted YOU!

i.e. if most of the powered DUTs you work with only pull in under 1 amp, why have that 10 or 20 amp isolation transformer monster powering it,
unless there is DUT inrush surges to consider?

Plus the junior sized one hums and buzzes less, easy to move about and find parking space,
and may be all you can afford at this time.
or if you can afford or have both, bring out the big one when needed 


Either way any of the above may be 50/50 coin toss 'luck' unless you read up and understand 'isolation' in all it's forms and RCD/GFCI pros, cons etc


You only have to spend that time learning and testing ONCE, verifying what you think you now know safely, and get on with it,

or toss coins for the rest of your long (or cut short) electo-life using and surfing suspect voltages

Personally I'd rather swap out fuses, reset breakers and RCDs,
and work from a a tested working isolation transformer,
and avoid the local street power transformer  trying to supply all it's current into the gear or me   

[nightfire]

To alleviate the fear of grilled by the street transformer: It only can do 230V in case of a short circuit in the DUT. Voltage in case of a real low impedance short also tends to drop a little, so basically the most annoying part of it would be particles moving away from the DUT with high velocity and/or temperature.
 This is also limited a bit by the impedance of the cable from the DUT to mains, which limits the short circuit current a bit. Rule of thumb: After 3 meter of 1.5mm², there can be onyl around 2000A- in reality, a standard outlet brings between 200A and 400A short circuit current- here the type of fuse you use would be important, as those clear glass fuses can break under this stress. So ceramic fuses are strongly recommended if you want to protect against shorts like this.

Also a reasonable fuse limits the short circuit current a bit, so that part of the (prospective) energy goes into melting the metal inside of the fuse.

Depending on the isolation transformer, you can change the fuse, so exchanging the mostly slow-blow fuses to faster ones or with lower rated current is also a way of getting them a bit more sensitive.

[tautech]

Think what I might do is build a lamp socket with a bypass switch and mount it up on the wall and keep a few incandescent bulbs laying around for current limiting, 40w, 60w, 100w, 150w flood. Use that for powering DUTs when needed otherwise use the bypass switch normally.

Too complex, just KISS.

That was a similar plan to what I had with an always ON DBT through the bulb and flick the switch the other way to bypass the DBT and supply full power to the DUT.
I just used that ^ setup for a very short time then became properly aware of the hazzard it was and changed the switching to just a series power switch to properly kill the power and not the user !

That's not to say you can't build something lots lots safer with dual switches or a 3 position switch but unless you're using it all day IMHO it's better to KISS.
Below is the DBT I knocked together with scrap from around the bench all those years ago and it's remained unchanged since the mods to make it safer.

[nctnico]

I couldn't find any seller that only sells one glove.

Bob has you covered:     www.bobthewelder.com.au/products/xt-left-handed-welding-gloves-green-long

---------------------

FWIW folks: 30ma RCDs rarely trip at 30ma

Anywhere from 15 to 28ma  is what usually happens, and a good unit will have about 2 to 3ma repeatability

i.e. test the suckers properly before trusting your life and gear with them,
better still, use two RCDs  piggy backed.
One of the two 'may' trip 'faster', or both will work if the trip current approaches zap city.

But they won't do you much good with an electrical fault or short in the chain, so..FUSE UP, just past the DUTs current rating,

and you won't need an imitation rabbits foot or garlic necklace 

Yes, unlike fuse or circuit breaker ratings, the RCD trip current is the maximum allowable for it to meet its standards.

Did'nt read the Eaton article but fully I doubt this statement is entirely true. There has to be a minimum as well so you have a defined amount of allowed leakage current. Otherwise it wouldn't make sense to sell unsensitive (300mA) and super sensitive (5mA) GFIs / RCDs

[AVGresponding]

I couldn't find any seller that only sells one glove.

Bob has you covered:     www.bobthewelder.com.au/products/xt-left-handed-welding-gloves-green-long

---------------------

FWIW folks: 30ma RCDs rarely trip at 30ma

Anywhere from 15 to 28ma  is what usually happens, and a good unit will have about 2 to 3ma repeatability

i.e. test the suckers properly before trusting your life and gear with them,
better still, use two RCDs  piggy backed.
One of the two 'may' trip 'faster', or both will work if the trip current approaches zap city.

But they won't do you much good with an electrical fault or short in the chain, so..FUSE UP, just past the DUTs current rating,

and you won't need an imitation rabbits foot or garlic necklace 

Yes, unlike fuse or circuit breaker ratings, the RCD trip current is the maximum allowable for it to meet its standards.

Did'nt read the Eaton article but fully I doubt this statement is entirely true. There has to be a minimum as well so you have a defined amount of allowed leakage current. Otherwise it wouldn't make sense to sell unsensitive (300mA) and super sensitive (5mA) GFIs / RCDs

If you had bothered to read the article, you would have found out that the regulatory requirement is that the device should operate at between 50% and 100% of the rated trip current, and that typical trip values for a 30mA RCD are 18-23mA, with a 2-3mA variance in repeatability for good quality devices.

[Electro Detective]

I couldn't find any seller that only sells one glove.

Bob has you covered:     www.bobthewelder.com.au/products/xt-left-handed-welding-gloves-green-long

---------------------

FWIW folks: 30ma RCDs rarely trip at 30ma

Anywhere from 15 to 28ma  is what usually happens, and a good unit will have about 2 to 3ma repeatability

i.e. test the suckers properly before trusting your life and gear with them,
better still, use two RCDs  piggy backed.
One of the two 'may' trip 'faster', or both will work if the trip current approaches zap city.

But they won't do you much good with an electrical fault or short in the chain, so..FUSE UP, just past the DUTs current rating,

and you won't need an imitation rabbits foot or garlic necklace 

Yes, unlike fuse or circuit breaker ratings, the RCD trip current is the maximum allowable for it to meet its standards.

Did'nt read the Eaton article but fully I doubt this statement is entirely true. There has to be a minimum as well so you have a defined amount of allowed leakage current. Otherwise it wouldn't make sense to sell unsensitive (300mA) and super sensitive (5mA) GFIs / RCDs

If you had bothered to read the article, you would have found out that the regulatory requirement is that the device should operate at between 50% and 100% of the rated trip current, and that typical trip values for a 30mA RCD are 18-23mA, with a 2-3mA variance in repeatability for good quality devices.

Now we're rockin',
 well said mate   

Seriously folks, what part of trusting fool zone is not clear, when prodding OUCH!/HOSPITAL/BBQ/MORGUE voltages

and trusting an RCD or GFCI, you struggled to release from a blister pack   with bolt cutters and oxy cutting torch

with entitlement to a refund, exchange, or gift voucher if faulty 

This comment is mainly aimed at newbies and overconfident amateurs, and many of us have been there at one time guilty as charged

Apparently pros never get zapped terminally by RCD GFCI fails,
and many that did past and present have never returned to tell us whether it was the current, voltage,
or pacemaker failure that did them in 

[Zero999]

I notice the original poster has deleted the first post. It does annoy me when that happens. There's no point in doing this. It just implies he's gone off in a strop.

To answer the question: yes, I have one on my bench in the lab at work. Not only does it provide shock protection, as the circuit has no RCD, but it occasionally comes in handy for probing mains circuits with an oscilloscope and it reduces the leakage on switched mode power supplies. It's a useful piece of kit. Obviously I'm fully aware of the dangers and don't rely on it to provide complete protection against shock. I know full well, when the 'scope is connected, the circuit becomes connected to earth, although I often use a battery powered Owon 'scope, to prevent that.

[nightfire]

On my bench at home I have also in my apartment no RCD installed for the wall outlet- cabling is older than standards dictate mandatory usage of RCD for every layman-operable circuit.
I got my hands on ebay on a new 19" power strip from Rittal, andd mounted a PRCD plug on it, so this power strip is protected by a 30mA RCD.
As an additional benefit the build quality of that strip is solid as a tank, and together it cost me less than 50 €.

[timeandfrequency]

I notice the original poster has deleted the first post. It does annoy me when that happens. There's no point in doing this. It just implies he's gone off in a strop.

I agree. Maybe he prefers being isolated from our answers.

[MrMobodies]

Let’s put it this way: if you don’t thoroughly understand why and when you’d want an isolation transformer, and what it does and doesn’t protect you from, then you shouldn’t work on mains-powered stuff yet, specifically, things with a live chassis.

If you get one, make sure you don’t let it lull you into a sense of false security, such that you actually let your guard down around mains voltages.

I am not an electrician but it reminds me of this video:
youtube.com/watch?v=FBeSKL9zVro
The most deadly project on the Internet (Wood fracking)

10:30 with a galvanically separated
transformer all it sees is the
current flowing in the primary so if
you're in the secondary which is
reference to earth and the current is
zapping through your body to ground and
finding its way back
that's a closed loop in there it is not
seeing it in that side it thinks it's a
normal load and the circuit protection
will not trip

[Nominal Animal]

As I play with microcontrollers and very low DC voltages only, I don't have nor need an isolation transformer, but I usually connect the projects to my computer via USB while developing and testing.  Me being the butterfinger I am, I have learned to use a cheap USB isolator (ADuM3160 clones off eBay, they're direct implementations of the datasheet/appnote, with the only difference being the isolated DC-DC converter used – which I recommend checking before relying on > 100mA of current being available) between the project and the computer, just in case.  My gadgets all tend to have native USB support.

I can't really tell if I've actually saved any hardware doing this, but it calms my nerves and reduces stress levels when poking at the project while it is running and powered.  It makes development more relaxed and fun.

(The only downside is that ADuM3160 is limited to full speed, 12 Mbit/s, but faster but roughly equally simple isolators like ADuM4165, ISOUSB211, etc., are still rare enough – chipageddon – to keep high-speed 480 Mbit/s isolator prices relatively high.  My Teensies have native high-speed USB, which is nice.  I guess I'll have to build my own damn isolators?)

Anyway, I wonder how many others use such equipment to limit damage to their tools because of their own butterfingery, and peace of mind, rather than as a necessary precaution for safety?

[tggzzz]

I notice the original poster has deleted the first post. It does annoy me when that happens. There's no point in doing this. It just implies he's gone off in a strop.

I agree. Maybe he prefers being isolated from our answers.

When I spot (and remember) someone has done that in the past, any reply of mine will "quote" their message so they can't pull that trick again.

[Gyro]

Ah yes, bigfoot22, a repeat offender. I't looks as if he went round and deleted the first post on all of his threads on the 11th.  [Edit: and all of his posts]

[Zero999]

Ah yes, bigfoot22, a repeat offender. I't looks as if he went round and deleted the first post on all of his threads on the 11th.  [Edit: and all of his posts]

He's deleted all of his posts.

Here's a link to a quote of one of his now deleted posts.
https://www.eevblog.com/forum/chat/your-pet-peeve-technical-or-otherwise/msg4691378/#msg4691378

It appears he's thrown his toys out of the pram and left. Did I miss the fireworks?

[Nominal Animal]

The sad thing is, when he calms down and realizes the effects of it, and how it looks, he'll want to undo it, but will not be able to. 

[tooki]

The sad thing is, when he calms down and realizes the effects of it, and how it looks, he'll want to undo it, but will not be able to. 

I somehow doubt that reflection is one of his strengths…

[iMo]

I made myself an isolation transformer mainly for measurements with my oscope. I did it simple way - with two back to back ~200W transformers (230/34V) off my junkbox, I added a fuse, sockets and a switch. It works, what I see as a minor issue is its weight and the power consumption of the combo without a load is around 30W

[Zero999]

I made myself an isolation transformer mainly for measurements with my oscope. I did it simple way - with two back to back ~200W transformers (230/34V) off my junkbox, I added a fuse, sockets and a switch. It works, what I see as a minor issue is its weight and the power consumption of the combo without a load is around 30W

How about rewinding one of them for 230V out?

I've done that before. At first I did a few too many turns and it gave 280V out unloaded, so I removed some until I got just under 250V out, with 230V in, unloaded and close to 230V at full load.

[ebastler]

Ah yes, bigfoot22, a repeat offender. I't looks as if he went round and deleted the first post on all of his threads on the 11th.  [Edit: and all of his posts]

He's deleted all of his posts. [...]
It appears he's thrown his toys out of the pram and left. Did I miss the fireworks?

Not sure what drove his decision, but he had certainly disclosed a lot of detail about his challenging personal situation in his posts. In my opinion it was a wise decision to remove them and let that published persona disappear.

I wish bigfoot the best for his future; hopefully he gets the right support and can turn things around for himself.

[pcprogrammer]

I wish bigfoot the best for his future; hopefully he gets the right support and can turn things around for himself.

Me too.

Must have been quite a job to delete his posts. I think he had near or over 500 of them. He could have left the ones that did not include bits about his personal situation. He did show willingness to work on his problem and try to earn money. Don't want to feed the ones that don't show this willingness. 

[Nominal Animal]

Not sure what drove his decision, but he had certainly disclosed a lot of detail about his challenging personal situation in his posts. In my opinion it was a wise decision to remove them and let that published persona disappear.

Perhaps.  I saw details that closely reminded of myself a decade and a bit ago, when I was really in a bad place, not having started cognitive-behavioural therapy yet.  Very, very close similarities, although my problems stem from my work history and lack of work-life balance.

I have been open about my own history, exactly because a large part of my problems was that I did not know how to speak about them, or even how to seek help.  My problems didn't/coudn't fester, but they certainly ground me down during the years.  Yet, having issues with depression and burnout is really no different than having a broken leg: in most cases, you can heal and become strong enough to not suffer anymore, even if you'll have some lingering effects like a twinge whenever the weather changes.  Some disagree, but they're wrong.

(I agree to removing the personal posts possibly being wise, simply because many people are stupid, and revealing anything about oneself makes one a possible target for stupid people.  I have considered that myself, and decided that the positive effects (of maybe helping someone consider checking if they need help) are much bigger for myself than the risk of being targeted by stupid people.  I already get targeted by stupid people for all sorts of reasons anyway, down to the choice of a mascot, one more isn't a big deal.  So, the best decision will definitely vary from person to person.)

[pcprogrammer]

I have been open about my own history, exactly because a large part of my problems was that I did not know how to speak about them, or even how to seek help.  My problems didn't/coudn't fester, but they certainly ground me down during the years.  Yet, having issues with depression and burnout is really no different than having a broken leg: in most cases, you can heal and become strong enough to not suffer anymore, even if you'll have some lingering effects like a twinge whenever the weather changes.  Some disagree, but they're wrong.

True, one can heal from a depression or a burnout, and I don't see it as a weakness to tell others about it. As written before, I have been there myself. But in my case, and probably in the case of many others, it is due to ones own personality that it happens. And this is one of the most difficult things to change. Your personality.

I had to learn to say "no" to avoid taking on to much work. In itself a lot of work is not a real problem, but when time enters the building it introduces stress. And that is where it went wrong for me.

(I agree to removing the personal posts possibly being wise, simply because many people are stupid, and revealing anything about oneself makes one a possible target for stupid people.  I have considered that myself, and decided that the positive effects (of maybe helping someone consider checking if they need help) are much bigger for myself than the risk of being targeted by stupid people.  I already get targeted by stupid people for all sorts of reasons anyway, down to the choice of a mascot, one more isn't a big deal.  So, the best decision will definitely vary from person to person.)

It is not just stupid people that might target someones weakness. Greed, vengeance, envy, etc. are trades of dumb as well as smart people.

[tggzzz]

(I agree to removing the personal posts possibly being wise, simply because many people are stupid, and revealing anything about oneself makes one a possible target for stupid people.  I have considered that myself, and decided that the positive effects (of maybe helping someone consider checking if they need help) are much bigger for myself than the risk of being targeted by stupid people.  I already get targeted by stupid people for all sorts of reasons anyway, down to the choice of a mascot, one more isn't a big deal.  So, the best decision will definitely vary from person to person.)

I regard being open about problems (technical, personal, personality, etc) to be a strength rather than a weakness, for two reasons:

• acknowledgement is the necessary precondition for improvement
• the information can smooth future plans and interactions, leading to a better result

Having said that, I won't mention something unless it is relevant to the audience. Sometimes that might be a public forum, sometimes a family member.

I won't mention it to random strangers unless there is a reasonably belief they might help. A few random strangers are malicious, most are uninterested in me (very sensibly!).

[Nominal Animal]

It is not just stupid people that might target someones weakness. Greed, vengeance, envy, etc. are trades of dumb as well as smart people.

Very good point; agreed.  In anger, in the heat of a moment, anyone can stoop that low, without thinking; it is only human.

I won't mention it to random strangers unless there is a reasonably belief they might help. A few random strangers are malicious, most are uninterested in me (very sensibly!).

Very sensible approach, I agree.  I do worry myself if I bring it up too often, because it is not something I consider a defining characteristic at all; more like an anecdote about ones work history, like a tale about a coworker dismissive of personal protective equipment losing a finger and an eye in an unfortunate, but entirely foreseeable, table saw and fluorescent lamp accident.  It is not useful to repeat such anecdotes too often.

[AVGresponding]

(I agree to removing the personal posts possibly being wise, simply because many people are stupid, and revealing anything about oneself makes one a possible target for stupid people.  I have considered that myself, and decided that the positive effects (of maybe helping someone consider checking if they need help) are much bigger for myself than the risk of being targeted by stupid people.  I already get targeted by stupid people for all sorts of reasons anyway, down to the choice of a mascot, one more isn't a big deal.  So, the best decision will definitely vary from person to person.)

I regard being open about problems (technical, personal, personality, etc) to be a strength rather than a weakness, for two reasons:

• acknowledgement is the necessary precondition for improvement
• the information can smooth future plans and interactions, leading to a better result

Having said that, I won't mention something unless it is relevant to the audience. Sometimes that might be a public forum, sometimes a family member.

I won't mention it to random strangers unless there is a reasonably belief they might help. A few random strangers are malicious, most are uninterested in me (very sensibly!).

Completely agree, and I have no hesitation in joining others wishing bigfoot22 all the best, and hope they can come back to the forum some day, as they made an actual contribution to the place, unlike some.

[giubin]

I just tried the ADuM4165 (on its eval board) and it's freaking good... the speed and the reliability.