First Lm3886

[AndrewT]

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.

[Atilla]

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)

[PJPro]

OK guys. Thanks. I'll go for an integrated module.

[pacificblue]

Originally posted by Atilla
(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.

- 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.

[AndrewT]

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.

[pacificblue]

Originally posted by AndrewT
Depending on the severity of the fault there could be a real risk to the users with the case cover still in place.

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.

[Stuey]

Originally posted by AndrewT
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.

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

[pacificblue]

Originally posted by Stuey
I hadn't thought it through. We have polarised plugs here.

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?

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.

[AndrewT]

Originally posted by pacificblue
Are the people, who live here in constant potential danger, when using equipment with two fuses?

no

Originally posted by pacificblue
Or the other way round. If equipment with both wires fused is safe here in Germany, ............. does not make it more or less safe. [/B]

that's where we will have to disagree.
And it seems our Authorities disagree as well.

[Stuey]

Originally posted by pacificblue

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?

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.

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