Discussion of AC mains isolation transformers

[JohnSwenson]

I'm learning so much about system noise on this forum. Makes me want to sell my flashy $1000 power conditioner for a cheap strip and a good isolation transformer.

 

 

John, what’s the role and benefit of an isolation transformer, in an audio context?

 

 

Am I right, that this plugs into your wall and you plug a powerstrip into the isolation transformer? Apologies for the silly question. This is a new world for me.

 

 

In Australia we have 240V power supply (or 230V) at the wall. If choosing an isolation transformer, do I would want something like a 2000watt transformer (minimum), delivering an 8amp current? Power boards are rated at 10amp max current here in Australia.

 

 

I'm looking to get my system optimised before LPS-1 arrives in November - I’ve just made my order :-)

 

But other than just the LPS-1, I'm looking to improve the system generally.

 

 

Many thanks in advance

 

The isolation transformer I'm using is a Topaz model, it is a very special transformer. It has extremely low inter-winding capacitance (.005pf according to the manufacturer). Most transformers have two mechanisms that transfer AC from one side to the other: magnetic and capacitive. The magnetic part is low frequency (it is what the 50/60Hz mains signal uses) and the capacitive is high frequency. The combination means that a "normal" transformer lets a lot of high frequency crud through.

 

With its extremely low capacitiance the Topaz doesn't pass the high frequency crud on the AV main, just the base line frequency and a couple harmonics. Thus it is a very effective noise filter.

 

In addition it is a very good surge suppressor as well. Most of the energy in high power surges is contained in high frequency components, which get suppressed by the low capacitance, thus it is quite an effective surge suppressor without needing any other special circuits to achieve this.

 

This isolation transformer keeps noise and surges from the rest of your house and neighborhood out of your audio system and fully preserves your safety ground.

 

Yes you are correct about the application, the Topaz plugs into the wall, the power strip plugs into it.

 

My recommendation is to use a simple power strip with NO filtering or surge suppression, the Topaz does it much better than what will come in almost any power strip. I plug EVERYTHING into thepower strip. This dramatically cuts down on the impedance between boxes, significantly lowering noise generated by leakage loops.

 

Some people will say "but then the noise injected back into the AC mains can go right into other boxes". Yes it can. BUT recent experiments have been pointing to the leakage loops being a significantly greater detriment to ultimate good sound than the injected noise. Of course different systems are different and this may not be true in all systems, but it is looking like this is a good place to start for many systems.

 

John S.

[JohnSwenson]

Something like this 2000 watt medical iso transformer even discusses leakage currents and already has 6 outlets which is sufficient for my system:

 

Medical Isolation Transformer IEC 601 and UL 544 Standard for Medical Instruments Australia

 

The medical transformers may not have very low capacitance between windings, their leakage current is usually speced between winding and ground NOT winding to winding.

 

The leakage current I have been talking about is winding to winding, not winding to ground. So just because something is "medical" it may not be doing much good for the leakage currents I'm talking about. The MAY be very good, they may not.

 

John S.

[JohnSwenson]

Hi John, a few people on other forums have commented that their Topaz hums, but an Elgar (also with a coupling capacitance of 0.005pF) doesn't. This humming that they speak of, does it contribute to electrical noise at all to music playback or is it purely just a faint audible hum that doesn't affect the sound quality at all?

 

Thanks again

 

Yes my Topaz hums a little, it is an acoustic Hum (the output is 60Hz AC which of course is the ultimate hum!). I built a box around it with some pillows for now. It does get a little warm so you have to be careful with thermal management.

 

Without the box I can hear it when I am standing near it, from the listening position I can just barely hear it with no music playing at 3AM when the house is very quiet. The refrigerator running a couple rooms away is much louder.

 

John S.

[JohnSwenson]

I'm definitely not answering on behalf of John here (not at all qualified to) but I've been emailing all the worlds major iso transformer manufacturers (even medical class) and none can come close to the <<< 1pF coupling capacitance.

 

But feel free to ask around and share if you can find a current production unit like this. It would have to be an expensive custom design and customer order I would think. I THINK that's why John mentioned the Topaz is a bit of a special beast.

 

The direct descendant of the Topaz is the Eaton Power-Suppress 100 series. They are the same transformer but enclosed in a rectangular metal box. They are in current production and several online companies sell them. They are not cheap ($600 range) but are brand new. If you want ones that plug into an outlet and have its own outlets make sure do NOT get a hardwired version. You can get both types, but a couple places just have the hardwired versions.

 

Ebay has a couple used ones.

 

John S.

[JohnSwenson]

...what about ethernet switch, router, TV screen (HDMI'd to computer)?

 

(This power strip's getting quite big!)

 

This is where you have to think about where leakage loops can happen. If a loop cannot happen, then you don't need a low impedance AC connection.

 

For example if the switch is connected via Ethernet cable that does NOT connect the shield, then you cannot get a loop through it so it does not need to be on the same strip.

 

If the TV is connected via HDMI to a computer and you have a USB connection from that computer to your DAC, then you definitely have a loop through the TV so it should be on the same strip. If you use a USB isolator (such as Intona) which blocks the loop over the USB then you can't get a loop from the computer so the TV doesn't matter.

 

This is one of the reasons that dedicated headless computers, streamers etc are popular, if their connection to the outside world is an Ethernet connection (without connected shield) that computer is the only part that needs to be part of the "all in one" strip.

 

John S.

[JohnSwenson]

Why not the hard wired version?

 

Also the Easton spec sheet says Impedance of 3-6%. What does this mean? Sounds rather high...

 

The hardwired versions work fine, I just want people to know what they are getting. The hardwired versions don't have a plug or outlets, just standard holes to mount conduit or BX etc. I don't want someone to spend the money to get one and find out they can't use it.

 

I'll have to spend some time looking at that spec, off the top of my head I have no idea what it means. The only thing that comes to mind might be something like power factor, but that is not usually speced that way.

 

John S.

[JohnSwenson]

Why not the hard wired version?

 

Also the Easton spec sheet says Impedance of 3-6%. What does this mean? Sounds rather high...

 

The impedance as a percentage relates to the increase in impedance brought about by the transformer. Thus whatever the impedance was of the line going into the transformer, the output impedance is that plus 3-6%.

 

Since isolation transformers are 1:1 devices, ideally out would be the same as in, but transformers are never completely lossless, so in order to have the same output voltage as input they have to make the ratio slightly different, such as 1:1.05 to deal with the transformer losses. This ratio gives a slightly higher output impedance than the input.

 

John S.

[JohnSwenson]

John

I have these connected to my mains box. Is this relevant?

http://ep2000.com/uploads/EP-2050_SeriesSpecifications.pdf

http://ep2000.com/uploads/EP_Ground%20Filter.pdf

 

If not, where do the receptacle Eaton boxes go? In the audio circuit or anywhere BUT the audio circuit?

 

How are these devices hooked up? Between the power company feed and everything in your house, or just on the wires feeding the audio system? If they are just on the audio system wiring then they are already doing some cleanup of anything coming from the rest of the house. But they are only good from 3KHz and up whereas the isolation transformers are good from 400Hz and up. That can make a big difference to an audio system.

 

So using the isolation transformer is still a good idea, it would still go between the wiring in the walls and the power strip where all the equipment is plugged in. So if using the one with plugs and outlets, plug the isolation transformer into the wall, and plug your power strip into the transformer.

 

The surge suppression techniques used by the device above and the isolation transformer are different, they work very well together, complementing each other.

 

John S.

[JohnSwenson]

Hello,

 

I am considering what John suggested i just don't know if these choices would serve the purpose and if, which can be the best choice:

 

It will be: Wall - Transformer - Strip - all system including Microrendu with LPS-1, Preamp, 200w Amp, DAC, MacMini, OPPO player and perhaps TV

 

Choices that i am believing are the ones John mentioned:

 

UPS & Uninterruptible Power Supplies | Eaton Power-Suppress 100 1kVA 120/240V In 120/240V Power Conditioner

 

TOPAZ 91001-12 Isolating Transformer 120V | eBay

 

Regards

 

Mike

 

These are essentially the same thing, but I am worried about the Topaz one since it has a Schuko plug, which is usually used in 230V areas. The tag on the transformer says 120V input, so something doesn't add up. If the transformer itself really is wired for 120V to 120V then you could just put a standard US plug on the cord, but if it actually has been modified to be 240 to 120 then it is a little more difficult to deal with.

 

John S.

[JohnSwenson]

Alex/John,

Hi. I am looking to get an LPS-1 into my system, likely to simply power the microRendu (instead of my JS-2, which I will solely use elsewhere in the system using only a single rail). My question is regarding your phone/answering system example (quote taken from another thread). And before I go on, I realize the LPS-1 is literally immune and isolated from this example, but a dirty wallwart is nonetheless leaking into the mains. Most people's dirty wallwarts within their home are hopefully not in the listening room and likely not on the circuit used for audio. I (ignorantly) assume that dirty wallwarts in the listening room's circuit are more likely to affect hearing that noise than when placed elsewhere in the house, so is your example relevant? Seriously, I ask ignorantly cuz I know 'everything matters" but if I am to worry about the whole house (and I do have whole house surge protection and ground loop protection installed at the mains box), then my first work would be with my refrigerator.

 

Anyway, what I am trying to ask is that is it worth it to use your included SMPS (or any other cleaner wallwart) on another circuit other than the audio one (solution in most people's homes would be a 25 ft extension cord to closest non-audio circuit)? If not, is it because all circuits would affect sq the same (which in your estimation, with the LPS-1 design, is almost nill anyway)? Thx

 

Hi Ted,

it's a question of degree. In most systems the sonic detriment from leakage current is much worse than the detriment from actual noise on the mains (noise between neutral and hot). If you DO get rid of the leakage loops, then issues relating to actual noise on the mains may have some small impact. The isolation transformers mentioned above will essentially eliminate any noise from the rest of your house getting into the audio system AC mains AND provide very good surge protection.

 

But even if you don't use the isolation transformer the actual amount of noise injected back into the mains from modern SMPS is pretty small. I did some tests of this recently and could not see ANY difference in the noise on my mains from the Mean Well SMPS. BUT the SMPS that came with my older headphone amp was a different story, it was bad. For some reason the SMPS from older networking equipment seems to be particularly bad.

 

So if worried about any of this, just use the isolation transformer on the circuit used for the audio system and that will make sure none of the noise from the rest of the house gets into the audio system.

 

John S.

[JohnSwenson]

A few quick words on what is happening with the transformers I have been talking about and how to setup a system using them.

 

It starts with the leakage loops I have been talking about recently. Remember these are loops that go through the AC mains, power supplies, DC output of power supplies, interconnects (audio and digital) to other power supplies and back through the AC mains. Note this has nothing to do with the "third pin" safety ground. I've gone over this in detail in other posts.

 

You can get rid of the noise generated by these loops in two ways, block the loop somewhere in the loop (The LPS-1 does this for certain paths), OR decrease the impedance along the loop, if the impedance is lower the NOISE generated by the CURRENT will be less.

 

This post is all about the AC side of this.

 

To decrease the impedance on the AC you need to have the lowest possible amount of wire, filters, anything else between the outlets you plug your AC cords into. This specifically means NO filters in the power strips, they dramatically increase the leakage currents between boxes plugged into such a strip.

 

Ideally you should have ONE power strip with EVERYTHING in your audio system plugged into that one strip. By everything I mean everything that has an AC plug that is connected into your audio system somehow. This includes power amps, computers etc.

 

Note this is the ideal situation, try and achieve this if you possibly can. For example if you are in a 120V area and you have two 700 watt power amps you can't do that, so some other arrangement will have to be made.

 

BTW the power strip for this does not have to be very expensive. I am currently using a $35 Tripp Lite power strip, no nothing inside, circuit breaker, switch, outlets and wires. Just this alone replacing my $1000 audiophile power filtering strip made a huge improvement in sound.

 

So now you have gotten rid of those expensive filtering power strips, doesn't that leave your system exposed to all the crud on the AC line from your other deices in your house and your neighbors as well? That is where the isolation transformer comes in.

 

These transformers with the very low interwinding capacitance are VERY effective noise filters AND surge suppressors without increasing leakage currents. MANY MANY of the filtering systems in your audiophile power strips DO filter out the noise, BUT they add large amounts of leakage currents into the system. These isolation transformers block the noise without adding leakage currents.

 

So the system as a whole is the isolation transformer feeding a very simple, very low impedance power strip with everything plugged into that power strip. This gets rid of external AC mains noise, deals with surges and provides a very low impedance AC mains path that significantly cuts down on the noise from the leakage loops.

 

Note it does not decrease the actual leakage loops, they are still there, it just decreases the NOISE generated by these loops, and THAT is what really matters.

 

So devices like the LPS-1 will BREAK loops from the digital side of things, which are usually the worst ones in a system, the above AC mains topology will decrease the noise generated by the leakage loops in the rest of the system, DACs, preamps, poweramps etc.

 

John S.

[JohnSwenson]

Hi John and Alex

 

Would these Topaz iso transformers have a power factor of 1? Or nearer to 0.8?

 

Trying to workout if 2.5kVA is close enough to 2500W or closer to 2000W

 

Very interesting question. I tested mine out and found the PF varied with load current. At low currents the PF was around 5. By the time it got to 10% of rating is was about 8.5. I didn't try higher than that. Somewhere I have a couple 200W halogen lights I could use to load the thing a little more and see what it does.

 

John S.

[JohnSwenson]

Thanks John ! I thought power factors ranged from -1 to +1 ? I am no expert, just relying on my limited googling abilities.

 

So I thought kW = kVA x Power Factor

 

 

Sent from my Blackberry DTEK50 using Tapatalk

Sorry, that was supposed to be 0.5 and 0.85.

 

John S.

[JohnSwenson]

Hi All, I have posted a message in the other thread which I would like everybody to read:

 

UltraCap™ LPS-1 Troubleshooting, system grounding, etc. - Page 3

 

I have received many PMs with people asking me if a specific power conditioner is good, bad better etc, the truth is I simply do not have the time right now to research every one of these devices and give informed opinions on them. I hope this post will give you some tools to evaluate them for yourself and make an informed decision about what to do.

 

I'm sorry if this feels like I'm putting a wet blanket on things, but If I did the research for everybody to the degree I would like to do, I would not have time to get any new products out!

 

Another thing in general is to realize that most isolation transformers are not the ultra low inter-winding capacitance ones, they will not have anywhere near the same degree of noise suppression or surge suppression. If they ARE they will probably let you know in the marketing literature. So if a specific transformer does NOT say anything about very low inter winding capacitance, it probably doesn't have it. You can always contact the manufacturer to find out.

 

I'm not going away or anything, I just have to cut down on the individual recommendation thing.

 

Thanks,

 

John S.

[JohnSwenson]

Once full digital part has been isolated, why not isolate only the dac with AC isolation instead of DAC + (preamp) + amp ? The transformer will be chapper and smaller.

HF are not critical for amp as they are for the DAC (except mabe for D class amp) and "leakages" the way J.S. describe them would be blocked.

 

 

Sent from my iPhone using Computer Audiophile

 

Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

 

Please read the post I linked earlier in this thread, the isolation transformer is NOT to provide leakage current isolation, it is a means to provide surge suppression and AC mains noise suppression from the outside world into the audio system.

 

This is important because I am recommending getting rid of the traditional "power conditioner" multi-outlet boxes with lots of filtering, in order to achieve very low AC mains impedance between boxes. Without the filtering when using a plain power strip (just wire) you need something else to provide surge suppression and outside world noise suppression. These extremely low capacitance isolation transformers do that in a very simple, elegant solution.

 

John S.

[JohnSwenson]

Can someone who uses a smaller to medium size Topaz comment on how much heat these units generate?

 

When sitting idle (with equipment also sitting idle but powered on) and when playing music?

 

Thanks.

 

I have the 1KVA Topaz, at full playing LOUD for hours at a time, it gets a little warm, only a few degrees above ambient.

 

My system is pretty low power, I have very efficient speakers and a 60W amp, the entire digital front end is taking about 10W. So I'm not pulling very much out of the Topaz.

 

Remember these are big heavy transformers, it takes a LONG time to reach thermal equilibrium (MANY hours).

 

John S.

[JohnSwenson]

I'm sure this is a very small sample size but I will ask anyway:

* has anyone who uses a Topaz/Eaton quality iso transformer ever used it with or replaced an Uberbuss (my power conditioner for my front end).

 

Also,a more general question, is the attack plan to first size and use a Topaz for the front end or for the amps (assuming one cannot find or afford to size for both)?

 

Hi Ted,

I'll cover the general question first, specifically where do you need the isolation transformer? It is there to provide external world noise suppression and surge suppression to a simple power strip with no filtering or surge suppression. THAT strip is used to provide extremely low AC mains impedance to help decrease the sonic degradation from leakage currents.

 

IF everything is plugged into the same simple strip you can only have one device to provide surge and noise suppression. The only way you can have more than one outside world suppressor is if you have two or more power strips, and that blows away the advantage from having the single simple power strip, you now have a higher impedance between groups of devices.

 

Remember the single strip is to decrease the degradation due to existing leakage loops, if you don't have any leakage loops you don't need the single strip stuff. So if you have a digital source powered by an LPS-1 and the DAC is also powered by a LPS-1 (either separately or VBUS from say a microRendu) and you are going directly into a power amp, then you can't have a leakage loop through the poweramp since the only thing connected to it has all ITS leakage loops blocked.

 

As to your specific existing power conditioner, IF it has nothing between outlets, just wire, then you can use it as is. IF it has anything other than wire between outlets (all three connections, a common ground is not sufficient), then you could use the existing conditioner as an outside world filter and plug a separate simple power strip into one of the existing outlets. This keeps the low impedance and gives outside world filtering. Something like the Topaz is actually a much better filter than what you have, but yours is much better than many others, so it is certainly all right to use it, you don't HAVE to switch to the isolation transformer approach.

 

I think it is a really good idea to make a diagram of all the audio equipment, power and signal connections, include any digital connections etc. From this you can trace connections and see where you have leakage loops through power supplies and come up with an approach to minimize the affects due to these. Make sure you include paths through power strips, power conditioners etc, they are part of the loops.

 

John S.

[JohnSwenson]

(If on the dac only)

 

 

Sent from my iPhone using Computer Audiophile

 

Tplink optical bridge/etalon streamer/audiogd nfb29/linn klout/athom sirrocco + athom rafale v38 hypex

 

Aha, you are talking about using the low capacitance transformer on just one component as a means of blocking leakage current through that specific component.

 

I don't know how well that would work. I have not tried that specific configuration. That depends on how well the transformer blocks leakage currents. If the component of leakage current that causes a problem is high frequency then it will probably work well. If the lower frequency components are important then the transformer will not be effective since it is designed to pass line frequency and close in harmonics. (usually stated that it passes up through 400Hz and starts suppressing above that)

 

That configuration might have some usefulness in some circumstances but in my looking at leakage current waveforms I see that most of the time the line frequency and close in components make up by far the largest component of the leakage current. But if it is just high frequency components that affect SQ it might work.

 

It would be an interesting test to compare a low capacitance transformer and an LPS-1 to the same component in the same system and see what the difference in SQ is.

 

John S.

[JohnSwenson]

@Superdad

 

The simple RC works very well, I will buy a handful and try them out.

 

The 330 Ohm resistor should be a plain carbon type, there's no need for precision, plus the wirewound types often go open due to dv/dt over a long period of time connected to AC mains.

 

For the 0.022uF cap, poly should be fine, they withstand repetitive voltages as well.

 

.

 

I usually use a 1% 1/2W metal film resistor (they are only a few cents) and Orange Drop polypropylene for the cap.

 

John S.

[JohnSwenson]

Forgive me if this is a silly question . . . Let's say I have a Topaz unit with duplex outlet, and I only need to power two devices-- an LPS-1 feeding a bus-powered DAC/amp, and a laptop. Would it be better to connect both devices directly to the two outlets on the Topaz, or connect a power strip to the Topaz and plug both devices in to the power strip? I'm asking because I've read posts stressing the importance of connecting all devices to one strip. I'm not sure whether connecting both devices directly to the Topaz would defeat some of the purpose of using the isolation transformer to begin with.

 

A duplex outlet is the same thing, there just metal between the two outlets, so if you just have 2 plugs, just plug them into the duplex outlets and be done with it.

 

John S.

[JohnSwenson]

Just wanted to open up my question to John above, to all here also

 

If you have a power strip which has no filtering between the outlets but it does have a circuit breaker, is this inlet protection of the power strip going to contribute to increasing the impedance between the outlets/boxes on this one power strip?

 

And thus does the circuit breaker contribute to increased noise generated by leakage currents?

 

I'm finding that even the custom powerstrip makers are hesitant to custom make me a powerstrip without a circuit breaker - this is fair enough too - safety first.

 

John mentioned the Tripp Lite but I can't find any of their models that don't have a circuit breaker, so I'm assuming the circuit breaker doesn't contribute to increasing the impedance between outlets?

 

Appreciate anyone's help/clarification

 

Many thanks in advance :-)

 

A circuit breaker by itself does not increase impedance between outlets, it is the "filtering" that causes the problems. I have been using a Tripp Lite that has the circuit breaker but nothing else, this seems to work well. I'm going to be eventually building my own.

 

John S.

[JohnSwenson]

I see some .005, and .001 pf capacitance Topaz units on ebay, but none .0005 units. I know lower is better, but how significant is this number. Thanks.

 

Remember the low capacitance is to decrease the transmission of higher frequency components from the AC "outside world" into your audio system. The capacitance determines how well it does this, so going from .005 to .0005 will mean the high frequency noise is suppressed even more. The .005 is already REALLY good at doing this. The one more zero is probably not going to matter in most systems.

 

John S.

[JohnSwenson]

Hello All,

 

I just measure the whole VA of my system, i have following others suggestions including John Swenson's and got the Tripplite strip and the Power monitoring "for Dummies", my system seems to display the following (see attached pic below) at high volumes, i don't know if i did something wrong cause my amp is a Hegel H200 (200watts) a Hegel P20 preamp, an Auralic Vega Dac, an Anthem MRX 700 receiver, a MacMini and the Microrendu (all connected to the strip and from there to the wall outlet):

 

[ATTACH=CONFIG]30537[/ATTACH]

 

Now with this measurement (If OK):

 

I am waiting for my LPS-1 for the MicroRendu, now i am towards deciding which Isolator to pick....

 

Which of the following choices from Topaz Isolation Transformers could suggest to work best, i mean all of them are 1KVA, seems to be more than enough from what i read, but in terms of condition and Capacitance.

 

TOPAZ ULTRA-ISOLATOR LINE NOISE SUPPRESSOR 91001-11 | eBay

 

Topaz 1kva ultra isolator isolation transformer 120/240:120/240 91001-21 | eBay

 

TOPAZ ELECTRONICS ULTRA ISOLATION TRANSFORMER 91001-21 Isolator .001pf 120/240V | eBay

 

Topaz 91001-22 Line Noise Suppressing Ultra-Isolator Transformer 1 kVA | eBay

 

TOPAZ POWER 91001-31 RQAUS1 9100131 | eBay

 

I am really NOT good at all with electronics and specs...

 

Help is needed and very appreciated

 

Thanks!

 

The fourth one down in your list is the only one with outlets and a cord so it is probably the one to go with. The picture does not show if there is a plug on the cord, you may have to add one yourself (very easy to do). I assume you are in the US so you use 120V? This one is 120 in 120 out which is what you most likely want for a room in the US.

 

John S.

[JohnSwenson]

Hey John,

 

While i am waiting for the LPS-1 and don't have the adequate power conditioner/Isolation transformer, i have been plugging every item of my system to the Tripplite and from it to the wall to an Oyaide wall outlet and i feel like the sound is more "dirty" at least more anemic . I used to have every gear direct to the wall with Oyaide wall outlets, do you consider that once the Topaz or similar in this equation things will better and noise will go down considerable? or do i need a dedicated PS for my system and the Topaz is only intended for the digital end?

 

Sorry if i am asking about already answered issues, i am a little lost here and just want to be sure that i will be putting my coins in the right place in the right order

 

Thank you

 

Regards

 

Miki

 

Are the Oyaide outlets all right next to each other? if yes then it IS already a very low impedance connection. The tripp Lite is probably notas good as the Oyaide. (but is a lot cheaper!) If you think the Oyaide sound better you have a couple oprions: keep them in the wall, you then get to wire the ISO transformer somehow into the outlets in the wall, OR build your own power strips with your existing Oyaide outlets (those ones from China listed earlier for this will be great for that).

 

If you currently do not have anything between the wall circuits and those Oyaide outlets then adding the Topaz should clean up a lot of noise on the line.

 

John S.

[JohnSwenson]

Greg Osborne (Osborne Loudspeakers) sells this: Untitled Document

 

8 international outlets, shielded box, no filtering/conditioning circuitry, IEC inlet so I can use my shielded power cable.

That might be the only option I'm left with but I'm in no rush - still looking around.

 

Quick question, how does a Schuko plug get a ground connection with that type of outlet?

 

John S.