Hi,
there is no "best".
Buy what suits your intended use.
Do not buy the 2pole fused version for UK use.
If the wrong fuse blows, it can leave the equipment live.
We, UK users, should never fuse the Neutral.
there is no "best".
Buy what suits your intended use.
Do not buy the 2pole fused version for UK use.
If the wrong fuse blows, it can leave the equipment live.
We, UK users, should never fuse the Neutral.
Sorry, forgot that you're in the UK.
Andrew is correct - do not get dual fuses for anywhere you can not reverse the plug. (Seriously, why is this allowed in over half of mainland Europe? It doesn't seem safe to me)
Andrew is correct - do not get dual fuses for anywhere you can not reverse the plug. (Seriously, why is this allowed in over half of mainland Europe? It doesn't seem safe to me)
It is safe as long as you don't forget to unplug the equipment before opening it. People, who work professionally with electricity follow certain safety rules before they start to service any equipment. I assume they are more or less the same all over the world. The German version goes like this.Atilla said:
- Disconnect from mains.
- Secure against re-connection.
- Make sure that no voltage is present (measure!).
- Short and earth.
- Cover or fence off neighboring live parts.
If you follow these rules, there will be no live voltage present, whether a fuse in the Neutral is blown, the mains plug was reversed or whatever.
Pacific and any others that want to listen.
You have missed the point.
We are talking about fusing both LIVE & Neutral and why, in the UK that has a polarised mains plug and socket system.
If a fault develops that blows one of the two mains fuses, the equipment will appear to turn off.
If the Neutral fuse has blown and the Live fuse is still intact there remains a risk of some component/s inside still being powered.
Depending on the severity of the fault there could be a real risk to the users with the case cover still in place.
Do not fuse the Neutral line, when polarised mains plugs and sockets are used for mains distribution.
You have missed the point.
We are talking about fusing both LIVE & Neutral and why, in the UK that has a polarised mains plug and socket system.
If a fault develops that blows one of the two mains fuses, the equipment will appear to turn off.
If the Neutral fuse has blown and the Live fuse is still intact there remains a risk of some component/s inside still being powered.
Depending on the severity of the fault there could be a real risk to the users with the case cover still in place.
Do not fuse the Neutral line, when polarised mains plugs and sockets are used for mains distribution.
How so? In Class I equipment the protective function of the PE would not be affected. In Class II equipment it should per definition not be possible that a live voltage appears on the case.AndrewT said:
AndrewT said:
Thanks for being the DIYA safety nerd, Andrew. 😉
My SKA has both fused simply because I hadn't thought it through. We have polarised plugs here.
I'm about to re-house it soon to obtain better cooling so will use the opportunity to modify the circuit to use the two fuses for live to the separate R and L transformers, rather than for the A and N for both channels.
Stuey
Here in Germany we have non-polarized plugs. Some equipment comes with none, some with one, some with two fuses. Are the people, who live here in constant potential danger, when using equipment with two fuses? Or when using equipment with only one fuse and the plug is turned so that the fuse is on the Neutral side?Stuey said:
Or the other way round. If equipment with both wires fused is safe here in Germany, why should it be unsafe in the UK? The fact that we can use it with reversed polarity and people in the UK cannot, does not make it more or less safe.
nopacificblue said:
that's where we will have to disagree.pacificblue said:
And it seems our Authorities disagree as well.
pacificblue said:
My understanding of what Andrew is saying is that it isn't that the equipment is less safe while there is no fault and you aren't attempting to repair it. However, once there's a fault and it happens to cause the fuse in the neutral line to blow, a user could be misled into thinking the internals after the fuse cannot be live...a dangerous assumption.
Yes, if you follow strict procedure regarding unplugging there's no problem....but if everyone was perfectly logical in their actions I guess no one would die from electrocution.
The polarised plug just ensures it's always the live that's fused, assuming someone hasn't mis-wired the mains cable. So I guess to the extent that this is a perceived problem, then your equipment in Germany may be less safe!
My understanding may be too simple. Maybe Andrew has a circuit fault scenario in mind I hadn't envisaged.
Stuey
If they did, those connectors would probably not be on sale in the UK. If they are ENEC certified, and many are, then they are automatically BSI approved as well.AndrewT said:
Neutral is at Earth level as long as no current flows through it.
As soon as a current flows through the Neutral wire, a voltage drop will develop. Although that voltage should not be very high in a well-done installation, it can be high enough to form a dangerous combination with wet skin, e. g. from transpiration.
As soon as a current flows through the Neutral wire, a voltage drop will develop. Although that voltage should not be very high in a well-done installation, it can be high enough to form a dangerous combination with wet skin, e. g. from transpiration.
Akis, at least here in Australia, there's a link between neutral and earth at the consumer's switchboard.
Pacificblue, do you have any arguments as to why we, in 'one way plug countries', should fuse Neutral? If so, what are they?
Stuey
Pacificblue, do you have any arguments as to why we, in 'one way plug countries', should fuse Neutral? If so, what are they?
Stuey
That link between Neutral and Earth in the consumer switchboard exists in most places. A cable goes from that distribution box to the wall outlet. That cable has a length and a diameter, thus an impedance. Connect anything to it and a current flows. Ohms law will confirm that a voltage drop ocurrs across that cable, hence the Neutral at the wall outlet is not at Earth level anymore. Here in Germany the permitted voltage drop from the energy counter to the wall outlet is 3 %. With a voltage of 230 V and permitted +10 % fluctutation there could be up to ~3,8 V present (the other half drops across the Phase wire), if the electrician has gone to the trouble of calculating the cable length and adjust the diameter. Most don't, so there can even be a bit more.
Current can paralyze from 10 mA upward. From 25 mA upward it can produce ventricular fibrillation (arrythmia), which has a severe impact on the further life of a person. From 50 mA upwards, AC current can kill 0,1 s.
The resistance of a grown-up person with dry skin is usually in the range of 500-3000 Ohm. It is lower, if the skin is wet from sweat or after coming in from the rain or after washing your hands. Use Ohms law to find out, if you want to touch that Neutral.
There is no reason, why you should fuse Neutral. You should however not be afraid of devices that come with a fused Neutral line or may end up with one. They will cross your path.
Current can paralyze from 10 mA upward. From 25 mA upward it can produce ventricular fibrillation (arrythmia), which has a severe impact on the further life of a person. From 50 mA upwards, AC current can kill 0,1 s.
The resistance of a grown-up person with dry skin is usually in the range of 500-3000 Ohm. It is lower, if the skin is wet from sweat or after coming in from the rain or after washing your hands. Use Ohms law to find out, if you want to touch that Neutral.
There is no reason, why you should fuse Neutral. You should however not be afraid of devices that come with a fused Neutral line or may end up with one. They will cross your path.
pacificblue said:
On your first point...good.
On the second; I already own a few devices with both lines fused (bought equipment, not DIY).
The reason I was changing my SKA was not because I was scared of it, but because I did always intend to fuse both transformers at A, but then decided that it'd be better to fuse both A & N. This has now been cleared up as of no benefit.
Thanks for the info.
Cheers
Stuey
Would a big appliance pulling a lot of amps somewhere far from the consumer panel make the neutral wire live close to that appliance (with respect to the earth) ?
Errr. Anyone know the difference between a standard and medical filtered module? They're about the same price. Is one better for audio?
See post #96.akis said:
One was tested according to EN60601 and complies with the demands for certain applications in certain areas in hospitals. The other was not tested, so may or may not comply, but must not be used in hospitals even if it complies, because it lacks the approval.PJPro said:
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