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3 Core Flat Twim & Earth for speakers


djmatthill

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A previous install has 3 core flat twin and earth installed to feed x2 250w 8 ohm speakers from the Amp.

 

I know flat twin and earth isn`t the first choice but I`ve seen many installers use this to save costs over the years.

 

Is there any major issues with this you can think off ?

 

Cheers

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The only issue I'm aware of is that on one occasion, a sparky, who should have know better, assumed 2.5mm T&E was a ring main cable and tried to break a spur in! Not sure how you prevent such stupidity, but thought I should put it up as you asked.

 

As for sound quality, even some audiophools swear by it. It's no good if the speakers or amp need to move. Solid copper cores will break remarkably quickly under regular movement.

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The wiring regulations differentiate between cable usage, so comms, telephony, audio cables will typically have some form of separation to maintain insulation standards and also help minimise interference. As T&E is almost always recognised as being "mains cable" it may be difficult to demonstrate (without lots of labelling etc.) that the T&E is actually an audio cable and therefore can be run in its own compartment with other audio cables.

 

 

Having said that, it works electrically from a cable viewpoint (although from a mechanical perspective I'd want to change to flexible tails where it goes to the amp and speakers). I have come across audio installs that have used T&E for induction loop cable and Pyrotenax for microphone cable. I've even seen flexible mic cables use the old style 2A round pin plug and socket instead of jack or XLR connections. None of these are really good practice (!) so I'd argue a dedicated speaker cable is likely to be a better approach.

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I think while 514 doesn't specifically say you shall not install speaker cable with T&E, you would be hard pushed to defend it's use and you are faced with the issue of how you identify.

In reality many controls cables in commercial building use 2 and 3 core mains flex for low voltage controls without ID.

Your principle ought to start from safety first though - the system needs to be readily identifiable to what it is, throughout the length of the cable without knowing what either end is connected to and without any prior knowledge of the building.

in terms of what can and can't work - back in the early 1980's I deliberately used mains cables. I rewired and orange 4x12 internally that had failing steel wire (anyone remember the 70's copper shortage). I used a single core extracted from some spare T&E and it worked marvellously. I also used to make up speaker cables (when jack to jack was the only common cable around) from orange mains flex - again great results.

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514

And specifically Table 51 - with the use of brown and blue colours. Although, who hasn't looked at the price of "dedicated" loudspeaker cable and decided that for an installation some two core mains or YY type cable would do the job just as well but at a fraction of the cost?

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  • 2 weeks later...

I think while 514 doesn't specifically say you shall not install speaker cable with T&E, you would be hard pushed to defend it's use and you are faced with the issue of how you identify.

In reality many controls cables in commercial building use 2 and 3 core mains flex for low voltage controls without ID.

Your principle ought to start from safety first though - the system needs to be readily identifiable to what it is, throughout the length of the cable without knowing what either end is connected to and without any prior knowledge of the building.

in terms of what can and can't work - back in the early 1980's I deliberately used mains cables. I rewired and orange 4x12 internally that had failing steel wire (anyone remember the 70's copper shortage). I used a single core extracted from some spare T&E and it worked marvellously. I also used to make up speaker cables (when jack to jack was the only common cable around) from orange mains flex - again great results.

 

 

So Can I assume that as long as there is a Speakon Connector fitted to it and it is plugged in to a Speaker Cabinet that any self respecting Sparky would NOT mistake it as a mains feed and this would satisfy the identification problem?

 

Also , the T&E is only a short piece (5 meters) used a tail and is terminated to (proper) 2 Core Speaker cable just above the ceiling area. This 2 Core cable then continues directly to the amp?

 

 

Would anyone be able to copy and paste the actual piece in the Regs. that relates to this please ?

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I don't think it would be an issue at all. Any "electrician" who just randomly connects mains to any twin and earth they find is not really an electrician. My only concern at using the cable would be that it's solid core and might require a transition to stranded in some situations.

 

There are some other crucial audiophile issues with using twin and earth.

 

1. It's not usually made of oxygen free copper.

2. Being designed for mains frequencies it might detract from the treble sibilance.

3. Proper audio cables are uni-directional for enhanced bass response.

4. It's very hard to find gold or silver plated twin and earth.

5. The fact it matches low grade mains wiring might result in unwanted inter-harmono sub-modulation.

6. The ground wire might need decoupled by a galvanic hyper-isolator to prevent audio misinabulisms.

7. It's too cheap for audio use with limited audiophile markup potential.

8. It would require solid gold mega connectors with trionic hex-force contacts and isolation gel.

 

I mean, by all means use it, but your sound system will sound like it is submerged in the audio equivalent of mud.

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