100 Volt Audio, Band I or Band II?

Good afternoon all. 

Thank you all for the replies, each of which is useful (and please do not let my reply cease the debate that has erupted).  

On defining whether 100 V audio is either Band I or Band II, I think it is debatable. 

As Mike an others point out, the RMS value (which voltage bands are tied to for AC) will vary with time, and the maximum RMS value will normally be short lived.  I would expect that higher frequencies of audio signals would be better at degrading insulation through leakage, than 50 Hz, but I also think that at those frequencies the leakage effect would not be an effective counterbalance to the shortness of the peaks in RMS voltage in terms of insulation degradation.  I have not checked that however.

As also pointed out by others, 100 V audio is likely to be isolated from earth, and so the audio voltage is not with reference to earth (i.e. it is separated).  

Hence on balance while it might be preferable to run 100 V audio entirely separately, I do not think there is a robust case to say that 100 V audio (being 100 V line to line and not with reference to earth) could not be run with Band I circuits.   

Does anyone disagree?

Thanks, once again.

Dutch of the Elm said:

Hence on balance while it might be preferable to run 100 V audio entirely separately, I do not think there is a robust case to say that 100 V audio (being 100 V line to line and not with reference to earth) could not be run with Band I circuits. 

It depends on whether those Band I circuits have separation requirements in their relevant supplementary installation standards, and those separation requirements may be for EMC or performance, as well as safety.


There's also the consideration of LPS/LPZ, and "hot" vs "cold" cabling.

And separation for safety services.

So, whilst "easy" for the general case, in practice, even not all Band I or Band II circuits can be run in the same containment as each other.

Dutch of the Elm said:

Hence on balance while it might be preferable to run 100 V audio entirely separately, I do not think there is a robust case to say that 100 V audio (being 100 V line to line and not with reference to earth) could not be run with Band I circuits. 

It depends on whether those Band I circuits have separation requirements in their relevant supplementary installation standards, and those separation requirements may be for EMC or performance, as well as safety.


There's also the consideration of LPS/LPZ, and "hot" vs "cold" cabling.

And separation for safety services.

So, whilst "easy" for the general case, in practice, even not all Band I or Band II circuits can be run in the same containment as each other.

Agreed!

Yep, you don't want mains Voltages appearing on speaker cables if they run together and there is a fault, such as mice chewing through the insulation and causing a short. Or other bad situations causing mains to appear at speakers and associated equipment like amplifiers.

Z.

and that is why the mains cables will be  insulated and sheathed, or armoured according toi the environment, - assuming you will allow the mains to be bare and insisting the speaker cable needs to be bomb proof is the wrong approach.

I

Mike.