First Lm3886

[pacificblue]

Originally posted by AndrewT
And it seems our Authorities disagree as well.

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.

[pacificblue]

Originally posted by Stuey
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.

A dangerous assumption, whether the fuse blows in Phase or Neutral.

[akis]

Neutral is not at earth level and can shock you, right?

[pacificblue]

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.

[Stuey]

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]

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.

[Stuey]

Originally posted by pacificblue
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. [/url]

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

[akis]

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) ?

[PJPro]

Errr. Anyone know the difference between a standard and medical filtered module? They're about the same price. Is one better for audio?

[pacificblue]

Originally posted by akis
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) ?

See post #96.

Originally posted by PJPro
Anyone know the difference between a standard and medical filtered module?

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.