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revor

Solar pv batteries distance to CU

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binky

sounds reasonable to me. I'm just a little surprised you managed to get 6mm meter tails - not seen those for years, and they confuse the hell out of other electricians. I would be inclined to fit 16mm to save arguments :^O.

 

First year of any apprenticeship is teaching basic use of tools. Simple stuff like how to drill holes and fit rawl plugs - so many oarents are hands-off these days, and schools no longer teach handskills, so youngsters are basically clueless. It's this that slows you down. Teaching safe isolation proedures is basic from day 1, but you have to also show the training college a paper trial of non sense like 'equal opportunites policies', 'complaints procedures' etc etc, which as a busy 1 man band, is time consuming. 

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revor

Thanks Binky. I'll take the supply from the other CU.  Yes students  are poorly equipped on practical work not how it was when I was at school. For a time I taught wood skills to young adults and was very surprised that some could not use a ruler or do simple sums e.g. divide a piece of wood into 2 equal lengths. Too much emphasis on academic subjects but a lot of kids are not able or willing to learn but have other skills to offer on the practical side of things but no longer get the opportunity to develop them, as where are the woodwork and metalwork classes now? They get bored and are disruptive to others.

https://www.edwardes.co.uk/categories/6-0mm-6181y-double-insulated-cable

Edwardes have a very good range of cut to length cables. Only recently used them. Got quite a bit of stuff from them for the install. Have found our local CEF very poorly stocked and what says on their store stock check is inaccurate but I think their web site is the best of the lot so easy to drill down to what you want, so get most from CEF  but I usually buy on line, click and collect or get delivered.

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Murdoch

I don't know you could still get 6mm tails. I use 16 or 25 as those are the ones I always have.

 

Beware the inspector who thinks that tails must be 25mm or it's a C2

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revor

25 mm tails are needed because  the main incoming fuse is 80 or 100 amps so 25 mm has rating of 90 to about 110 amps depending on fix method.  The onsite guide states minimum of 25 mm.  Anything less of a cable could not take the current and would overheat  and possibly blow before the company fuse went. So in this situation you would not use 16 mm tails on a 100  A fuse. So in what situation do you use 16 mm tails.?

All my main CU's  of which there are 3 are 25 mm tails (reference c fixed) because they are all connected via a Henley block  and through the meter to the incoming company fuse.

The inverter max output is 32 amps so using 6 mm cable is consistent with this (46 A method c.) The inverter feeds the privileged loads consumer unit (number 4) via grid / battery the consumer unit tails is protected by the inverter feed 32 AMP MCB and the  changeover inverter feed in event of inverter being down is via a different 32 A MCB. 

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Murdoch
40 minutes ago, revor said:

So in what situation do you use 16 mm tails.?

 

 

60a or 80a DNO fuse

 

OR 

 

a 2nd CU with a small load - say a hot tub or similar when 10mm or even 6mm would be more than adequate.

 

As for the OSG ......... oh dear.

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revor

 So no real difference to my 6mm  tails on a 32 A MCB providing power to the small load CU inverter privileged ?  

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binky
8 hours ago, revor said:

 So no real difference to my 6mm  tails on a 32 A MCB providing power to the small load CU inverter privileged ?  

 

Within the regs somewhere is a statement that suitable overload protection can be provided at either end of a cable, so the fact you have a single fixed load cct on a 32A MCB is adeqaute to protect the tails. 

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