attaching speaker cable to UPVC architrave

[JohnW2]

A few points
1/ most amplifiers include circuitry to protect the output stage in the even of a fault occurring e.g. a short circuit on the speaker leads
2/ It is rare for an amplifier output to be referenced to earth so the chance of detecting inbalance owing to contact is nil.
3/ voltage is such that there is zero risk of any hazard to life or limb, except in a 100V line system, even there insufficient current is available.

I'm sure that no-one is suggestion that there is any rational reason to RCD protect a speaker cable - except, conceivably in the very rare (and certainly not domestic) situation of a high-voltage, high power, situation and, even then, a standard RCD may well not be appropriate. The point is that I thought (although BAS now seems to be disagreeing) that the infamous 'book' had failed to distinguish between this sort of situation and standard domestic LV wiring.

Kind Regards, John

 

[ban-all-sheds]

What "it" refers to RCDs "having the characteristics specified in 415.1.1"?

The section(s) of the regulations which talk about the requirements for concealed cables.

I'm not sure that I understand. 415.1.1 doesn't say anything about what the RCD is 'for' - the only 'characteristics' mentioned appear to be the IΔn and trip time at 5*IΔn, characteristics which would be true of any 30mA RCD one could have, regardless of how daft/inappropriate might be the circuit in which one installed it.

OK, fine.

Please go away and find an RCD with an IΔn of ≤ 30mA and an operating time of ≤ 40ms at 5IΔn which will work at the voltages and frequencies found in speaker etc cables, and which has a mechanical design which allows it to be installed at the start of a run of concealed speaker etc cable.

 

[bernardgreen]

The RCD for loud speaker systems may be existed about 50 years ago.

On a 100 volt public address distribution system to several hundred speakers there were boxes that automatically disconnected branches that had faults from the trunk.

(( 100 volt audio distribution systems send the audio out at up to 100 volts ( or more ) and each speaker has a transformer to reduce it to a couple of volts for the speaker ))

 

[JohnW2]

Please go away and find an RCD with an IΔn of ≤ 30mA and an operating time of ≤ 40ms at 5IΔn which will work at the voltages and frequencies found in speaker etc cables, and which has a mechanical design which allows it to be installed at the start of a run of concealed speaker etc cable.

As I implied before, I don't suppose I would be able to find one - but, as I said, the 'characteristics specified in 415.1.1' say nothing about suitability for any particular frequencies and voltages (not sure what voltage has got to do with it - RCDs are all about current!), let alone it's appropriateness for installation in a particular place.

Kind Regards, John

 

[ban-all-sheds]

The RCD for loud speaker systems may be existed about 50 years ago.

On a 100 volt public address distribution system to several hundred speakers there were boxes that automatically disconnected branches that had faults from the trunk.

100V is not ELV.

 

[bernardgreen]

If the music or speech was low volume then the voltage wouldn't be anywhere near 100 volts so it would be ELV, it only became LV when the music was loud or the person speaking was shouting........

 

[ban-all-sheds]

As I implied before, I don't suppose I would be able to find one

Do you think they exist?

but, as I said, the 'characteristics specified in 415.1.1' say nothing about suitability for any particular frequencies and voltages (not sure what voltage has got to do with it - RCDs are all about current!)

So the circuitry inside an RCCB, or RCBO, will work with a supply voltage of a few volts and a frequency up into the 100's of MHz? Even if the answer is yes to the former, what about the latter? I think BS EN 61008/61009 specifies 50/60Hz for Types A and AC, and 1KHz for Type B.

let alone it's appropriateness for installation in a particular place.

You can't say "let alone.." and that's fundamental. Do you think they exist?

 

[JohnW2]

As I implied before, I don't suppose I would be able to find one

Do you think they exist?

Why do you imagine that I don't think I would be able to find one? If I thought they existed, I'd trust my ability to be able to find one!!

So the circuitry inside an RCCB, or RCBO, will work with a supply voltage of a few volts and a frequency up into the 100's of MHz? Even if the answer is yes to the former, what about the latter? I think BS EN 61008/61009 specifies 50/60Hz for Types A and AC, and 1KHz for Type B.

I agree that any RCD/RCBO which involves electronics will not work below a certain voltage (although purely electro-mechanical ones would not even know what voltage they were dealing with). However, I don't know why you keep saying all these things, since 415.1.1 says nothing about any of them. The only 'required characteristics' it specifies are the two I have already mentioned (for which it doesn't state an operating voltage or frequency).

Kind Regards, John

 

[securespark]

My AMP has SC protection on the speaker output: the amp goes up in smoke and fuses pop if you short the speaker leads out....

What the fault current is, I don't know!!

 

[ban-all-sheds]

Why do you imagine that I don't think I would be able to find one? If I thought they existed, I'd trust my ability to be able to find one!!

So you don't think they exist.

Neither do I.

However, I don't know why you keep saying all these things, since 415.1.1 says nothing about any of them. The only 'required characteristics' it specifies are the two I have already mentioned (for which it doesn't state an operating voltage or frequency).

Indeed it does not, but then nor does it mention any BS/EN standards with which any RCD would have to comply, but I don't think that means that when you install an RCD that it doesn't have to comply with any of the applicable BS/EN standards.

And this is of fundamental importance.

You don't think that any RCDs exist which are designed to be used on, or suitable to be used on, speaker/data/etc wiring.

Neither do I.


So - do you really think that the Wiring Regulations mandate the installation of something which does not exist?

I don't.

 

[ban-all-sheds]

the amp goes up in smoke and fuses pop if you short the speaker leads out....

Not much point to the fuses if the amp still goes up in smoke.

What the fault current is, I don't know!!

1. Use an oscilloscope to judge the output voltage (or a signal generator and an RMS multimeter).

2. Find the output impedance of the amp.

3. Apply Ohm's Law.

 

[bernardgreen]

If only it was that simple.

 

[JohnW2]

So - do you really think that the Wiring Regulations mandate the installation of something which does not exist? I don't.

I would hope that, even if one asked them, even the IET would not dream of suggesting that such was their intention.

As so often, this discussion has persisted and get bogged down with details. It all started because I merely commented that I'd never really noticed before that the regs do not very satisfactorily (certainly not explicitly) distinguish between standard LV house wiring and various types of ELV wiring (alarms, 'signal'/'control', AF, RF etc.) when specifying requirements in relation to, say, buried cables. That's all - just an observation - I really wasn't looking for a debate!

Kind Regards, John.

 

[ban-all-sheds]

I would hope that, even if one asked them, even the IET would not dream of suggesting that such was their intention.

Do you think that one needs to ask them?

I don't.

It all started because I merely commented that I'd never really noticed before that the regs do not very satisfactorily (certainly not explicitly) distinguish between standard LV house wiring and various types of ELV wiring (alarms, 'signal'/'control', AF, RF etc.) when specifying requirements in relation to, say, buried cables.

Well, unless you think that the regulations specify the use of an item which does not exist then the regulations do so distinguish.

Do you think that the regulations require the use of an item which does not exist?

 

[JohnW2]

I would hope that, even if one asked them, even the IET would not dream of suggesting that such was their intention.

Do you think that the regulations require the use of an item which does not exist?

As I said, I was not looking for a debate, least of all a silly one. You must be very short of things to amuse yourself with today.

Kind Regards, John