Circuit breaker - which to choose

[radix]

so you are suggesting that i should immediately use floating earth ie separate line for ground?
ah okay, in that case i will have to make rewire everything.

No, I'm not saying to float the earth. That has all sorts of other problems, as you can build up a charge on the case from the magnetic field.

The best thing would be to get a proper 3-conductor outlet. But I'd defer to someone who really knows consumer electronics safety about using it with a N+E bridge.

In regards the to link, it's probably home depot trying to do location-dependent service. Just google "gfci without ground."

 

[NTK]

can u open that url?

Access Denied​

You don't have permission to access "http://www.homedepot.com/c/ai/gfci-vs-gfi/" on this serve

Try this one.

GFCI vs GFI

Brush up on GFCI vs. AFCI, the uses of GFCI circuit breakers and outlets and where GFCI are required.

www.homedepot.com

 

[roxor]

@radix maybe i dont know whats floating ... to float the earth mean?

what is a proper 3-conductor outlet?

 

[roxor]

Try this one.

GFCI vs GFI

Brush up on GFCI vs. AFCI, the uses of GFCI circuit breakers and outlets and where GFCI are required.

www.homedepot.com

insane even i google it .. it shows the link / partially content but i cant open it ;/

 

[NTK]

insane even i google it .. it shows the link / partially content but i cant open it ;/

I am copying the section on GFCI working without ground here:

​

Will a GFCI Work Without a Ground?​

​

A ground is not required for a GFCI to function. GFCI devices work by detecting the current flowing from the hot to the neutral wires. Any imbalance trips the device, so a ground is not required. Older homes and buildings not designed to current electrical codes can still have GFCI protection.​

​

GFCI outlets installed without a ground may not trip when inspected with a voltage tester, which do require grounds to work. The device can be tested with the test button integrated in the outlet.​

​

To fully comply with NEC regulations, GFCI devices installed without grounds must be marked “GFCI Protected” and “No Equipment Ground” on the plate.​

​

 

[audio_tony]

argh,.. Its connected to the neutral.

In the UK most installations use the TN-C-S grounding system (earth to neutral).

Which country are you in, as the regulations for your country will state how your home should be grounded.

Please be careful about taking advice about grounding schemes and earth leakage detection using an earth leakage circuit breaker, as standards may vary from country to country.

An earth leakage breaker in the UK is rated to trip at 30mA (that means that if it detects 30mA of current flow to ground it will trip).

 

[JustJones]

@voodooless

My wall 230V sockets contains 2 cables, ie L and one more cable which is used to bridge N+E,
as per my understanding i wont be able to use CB with GFCI,
in case i want to use the one with GFCI then i need to rewire flat, and each 230V wall socket has to be connected to 3 separate lines ie L, N, E.


appreciate
View attachment 355713

This looks like North American type breaker and receptacle. I thought you are in EU ?

Contact a reputable local electrician and explain what's going on. I would hope they would know the appropriate breaker you need.

 

[roxor]

In the UK most installations use the TN-C-S grounding system (earth to neutral).

Which country are you in, as the regulations for your country will state how your home should be grounded.

Please be careful about taking advice about grounding schemes and earth leakage detection using an earth leakage circuit breaker, as standards may vary from country to country.

An earth leakage breaker in the UK is rated to trip at 30mA (that means that if it detects 30mA of current flow to ground it will trip).

View attachment 355765

at the moment Czechia.

 

[roxor]

This looks like North American type breaker and receptacle. I thought you are in EU ?

Contact a reputable local electrician and explain what's going on. I would hope they would know the appropriate breaker you need.

currently EU - Czechia.
ah u guys dont know what kind of ppl/ experts and technicians live here

 

[Blumlein 88]

There are such devices, but none AFAIK are consumer addons. They are rather inexpensive circuit elements, so I don't know why MF would not have used them. -- maybe they did and your's is bad?

https://www.digikey.com/en/products/filter/inrush-current-limiters-icl/151

AFAIK, we only have one photo of inside the PSU, but there are other things in there besides the transformers. Without a service manual or detailed photos, I don't think one can say much about what might or might not be causing the problem.

They used choke style power supply.

 

[radix]

@radix maybe i dont know whats floating ... to float the earth mean?

what is a proper 3-conductor outlet?

I'm going to speak about the USA, which is what I know.

Here, we get L1, L2, and N from the utility. It's 110-120V per L1 and L2, or 220-240V for a 4-wire system like a dryer or induction cooktop.

At the entry to the home, there is an earth ground, G, (a long copper rod in the ground). N is tied to G at that one place, the main service panel at the entry of the house. Every outlet gets L (either L1 or L2), N, and G. Sub-panels also keep N and G separate. In this setup, all current flows via L1/L2 and N.

In the old days, it was only 2-wire (L + N) per outlet. Or sometimes G would be tied to different ground rods under the house.

Under normal conditions, G carries no current to/from an outlet. If there is an electrical fault, current will be shunted to G. This causes GFCI breakers or outlets to trip. If there is not a G (you only have L and N), then the fault is usually via a poor person who touched something bad, or for example, if there is a short to the metal case and a person touches the metal case.

If you only have 2 conductors to an outlet in your building, that means they either floated G or tied G to N at the outlet. By floating G, I mean not connecting it to anything.

If a product is designed to have an earth ground, then floating G is likely dangerous. If it is a 2-wire consumer product designed for use without a G, then they have hopefully taken proper precautions to protect the consumer from a fault, like using a plastic or non-conductive case and controls.

There's a fair bit of engineering that goes into electrical safety of consumer products that I'm not very familiar with, so please don't take anything I say as a recommendation to do something.

If G is tied to N at the outlet, and you draw 100A inrush, that will create a voltage difference over your wire in the wall. If that 100A is on the ground terminal, then the metal case of your system will see that voltage. Let's say you have 0.5 ohms of wire in the wall. V=IR => V = 50V. It's super brief, but not safe, in my opinion. If G is floating, you might still induce a voltage in the metal case from the transformers.

So, if you are sure that your outlet only has 2 wires, not hot + neutral + ground, then you might want to ask an electrician in your area about getting a proper ground run. That will put the metal case at near 0V even when you have 100A running between hot + neutral.

 

[audio_tony]

at the moment Czechia.

I searched for electrical regulations in Czechia and the closest I could find was this forum post from 2011

It looks as though whatever earthing system you have will be defined by the age of the building you live in.

What Earthing system do I have?

Hi, I live in the Czech Republic and I have an old consumer unit that needs updating, and on inspection, it has an unusual earthing system (possibly not unusual for the Czech Republic). Here is a basic diagram: It's a 3-phase system with a earth wire heading towards the ground ( I am...

www.diynot.com

 

[roxor]

hi,
i found some more detail in the revision report from the whole building and there is stated:

 

[radix]

hi,
i found some more detail in the revision report from the whole building and there is stated:
View attachment 356075

See https://www.asutpp.com/pen-conductor.html

You need an electrician to look at how your specific outlets and panels are wired.

The TNC/TNCS and PEN/PE+N generally describe how the utility delivers power to the building. You can split a PEN to a PE+N at the main distribution panel. All you really care about is if a particular outlet has a current-carrying protective ground or a split non-current carrying protective ground.

You can have a PEN (where the N and PE and bridged) or a PE+N (where the PE and N are separate) depending on how it was wired. If you have a 2-conductor outlet, then its bridged. If you have a 2-conductor with exposed ground, then you have a separate PE return.

There's many ways buildings are wired and it changes over time. I would never trust a label on something much less an as-built plan. You need someone to look.

 

[roxor]

@radix thanks
i will have electrician visit, is it possible formulate
what exactly do i have to require ie what Ground setup would be best so i can task that to him?

just to articulate requirements to him ... and also i believe there is 3phase option.



Thanks

 

[audio_tony]

what Ground setup would be best

There is no 'best' ground setup. The ground setup used should be in accordance with the rest of the building (if an apartment block) or according to current standards if a house.

 

[radix]

@radix thanks
i will have electrician visit, is it possible formulate
what exactly do i have to require ie what Ground setup would be best so i can task that to him?

just to articulate requirements to him ... and also i believe there is 3phase option.



Thanks

If you have a large inrush current, then IMO a current carrying protective earth ground for a metal chassis is not ideal. It will build up a voltage during that period. Let's say you have 2mm (12 AWG) copper wire and the distance is 10m to the protective ground (just to make the math easier). 12 AWG wire will be about 5 ohms / 1000m, so you have 0.05 ohms in the wire. If the inrush current is 100A, then you have V=IR = 5V. In the previous example I gave, I had a much higher resistance. Maybe 5V is OK, maybe you'll fell it if you touch the case. Again, all those numbers are just an example. I do not know the wiring codes where you are, so it may not even be an option to switch your grounding. Or it may be you have to run all the way to the distribution panel and it is not economically practical.

3-phase is a totally different beast. Only specialized equipment uses 3-phase. You may very well have 3-phase coming in to the building that is then converted for used by individual branches. That's 220V per phase, or 400V between phases, so you could get massive power out of it. I believe in the EU, each single phase is simply one of the 3-phase loads (i.e. L1+N, L2+N, L3+N is 3 single phase loads). In the US, 3-phase to 1-phase requires a transformer if it's 480Y/277V not 208Y/120V. And it also depends on if it's 3-wire (delta) or 4-wire (wye) service. It gets complicated and is very dangerous.

As I've mentioned, I'm not an electrician so nothing I say should be considered advice (apart from where I say talk to an electrician!).

I would explain the situation to him: I have an amplifier with large toroidal transformers that seems to have a large inrush current, as it sometimes trips the breaker. Do I have a non-current carrying protective earth? if not, should I get one and how much $? Should I switch to a slower circuit breaker?

He should be able to inspect your panel and your outlet and let you know what can be done.

Have you inspected the fuses in the PSU, and are they the correct ones?

 

[roxor]

See https://www.asutpp.com/pen-conductor.html

You need an electrician to look at how your specific outlets and panels are wired.

The TNC/TNCS and PEN/PE+N generally describe how the utility delivers power to the building. You can split a PEN to a PE+N at the main distribution panel. All you really care about is if a particular outlet has a current-carrying protective ground or a split non-current carrying protective ground.

You can have a PEN (where the N and PE and bridged) or a PE+N (where the PE and N are separate) depending on how it was wired. If you have a 2-conductor outlet, then its bridged. If you have a 2-conductor with exposed ground, then you have a separate PE return.

There's many ways buildings are wired and it changes over time. I would never trust a label on something much less an as-built plan. You need someone to look.

the guy was here ...
he said i have 2x25A or 1x25A option

He mentioned that main connect is TN-C and then he mentioned that ground will be as PEN where P/ E/ N each will be separate to the wall sockets..
is that okay?
thanks

 

[roxor]

Do I have a non-current carrying protective earth?

what exactly is that?

Have you inspected the fuses in the PSU, and are they the correct ones?

there are 2x 15A fuses ... each one per one toroidal transformer.

 

[radix]

what exactly is that?


there are 2x 15A fuses ... each one per one toroidal transformer.

Regarding the fuses, doesn't the back panel say "T12.5A @ 220-230V"? It seems like 15A is the wrong fuse. I believe it's supposed to be a slow-blow fuse too. You might want to check with a MF tech to see if you have the correct fuses. I'm going by a photo of the PSU I found on the internet, so maybe I have the wrong PSU.

There are several ways to get a grounded outlet. One way is to have a 2-conductor (insulated) wire plus a ground, which is usually bare copper. Neutral is tied to an earth ground at the point of entry, usually by an 8' copper rod pounded into the ground. Another way is to have only a 2-conductor (insulated) wire and tie the ground of the outlet to neutral, then somewhere -- usually at the point of entry -- neutral is tied to ground. There are several other ways.

Having a 2-conductor with separate ground means the ground normally has no current on it, because nothing is shorting to ground. Without current, there is no voltage drop. So the metal chassis, say of a giant amplifier, will be close to 0V relative to ground.

If you have only a 2-conductor outlet with ground tied to neutral at the outlet, then there is current on the ground. This means there will be a voltage on the ground, and thus on the metal chassis. usually, the neutral resistance is low and current modest, so the voltage is small. But if you have a toroidal (or 3) pulling giant inrush current, there will be a brief period where that voltage on the ground (and thus the chassis) is not so small.

Electrical distribution networks (the utility) and house wiring have many ways to do things and sometimes the methods are mixed over time. Please consult a local electrician about any changes.