Whats the biggest shower I can fit please?

[Spark123]

Sorry, see edit !

 

[Softus]

Sorry, see edit !

I get you now.

 

[scotster]

So do I conclude changing the fuse to 45A is a non-starter?

NOT That I ws going to. More hypothetical really...

 

[Softus]

So do I conclude changing the fuse to 45A is a non-starter?

Yes. It would be the wrong thing to do.

 

[scotster]

Thankyou Sir!

One last question.

I assume sticking a large junction box in line of will derate the 6mm cable? The junction box would be acting as a straight through connector to a new lenght of 6mm to extend it by a few metres.

If I cant do that I may as well run a new length of 10mm anyway as the 6mm wont reach the new switch position....

 

[Softus]

I assume sticking a large junction box in line of will derate the 6mm cable? The junction box would be acting as a straight through connector to a new lenght of 6mm to extend it by a few metres.

Junction boxes are not favoured for such a high load application, because of the risk of a poor (high resistance) termination (connection) and the heat that would be generated; also the tendency for them to end up being inaccessible.

If there was no alternative to extending, then the recommended method would be by crimping, which ensures a connection that no man can put asunder.

If I cant do that I may as well run a new length of 10mm anyway as the 6mm wont reach the new switch position....

That would be the best solution, by far.

 

[ColJack]

Junction boxes are not favoured for such a high load application.

just out of curiosity then... do they even make 45A JB's? and if so, why?

 

[Softus]

just out of curiosity then... do they even make 45A JB's?

They make 60A ones.

...and if so, why?

For joining cable runs.

 

[equitum]

Junction boxes are not favoured for such a high load application, because of the risk of a poor (high resistance) termination (connection) and the heat that would be generated;

Could be said of any termination whether its at the consumer unit, junction box, double pole switch, appliance etc. Joints and terminations are part and parcel of the installation. Thats why we ensure the terminations are sound during inspection and test the circuit prior to energising, to ensure the continuity and resistance of the circuit is OK.

And what about 100A Henleys ? They are 100A, I've no problem using those either...

Personally I don't have a problem with the JB. Provided it is accessible, otherwise agree crimp the cables. (ps. after crimping should you wrap the whole lot in tape or heatshrink or other ?)

 

[Softus]

Personally I don't have a problem with the JB.

In that case, please feel entirely free to recommend the use of a JB to scotster. I'm sure he'll be delighted to hear from you.

(ps. after crimping should you wrap the whole lot in tape or heatshrink or other?)

Since it's likely that you already know the answer, why don't you ask the question you really have in mind?

 

[davelx]

A 9k5 shower on stage 1 heating will probably not trip a 32A breaker on a 6mm cable

Eh? A non-faulty 9.5kW shower, even on full chat, will definitely trip a 32A breaker, even on 1mm² cable.

According to the curves on page 199 of the regs, a 32A type B will not trip for >10000 seconds at 41A, so I'm interested to know the basis of this statement.

 

[equitum]

ps. after crimping should you wrap the whole lot in tape or heatshrink or other?)
Since it's likely that you already know the answer, why don't you ask the question you really have in mind?

I don't know the answer, have done both, just curious to know what others do, thought that was the idea of a forum ?

 

[Softus]

A 9k5 shower on stage 1 heating will probably not trip a 32A breaker on a 6mm cable

Eh? A non-faulty 9.5kW shower, even on full chat, will definitely trip a 32A breaker, even on 1mm² cable.

According to the curves on page 199 of the regs, a 32A type B will not trip for >10000 seconds at 41A, so I'm interested to know the basis of this statement.

The basis was my incompetence in construction of that sentence. I was attempting to point out that the cable size was irrelevant to the let-through energy, and made a hash out of it.

I agree that at a steady I/In of 1.23 (assuming 9k5 at 240V), the tripping time will be well in excess of the likely showering time, and apologise if I misled anyone.

 

[Softus]

I don't know the answer, have done both, just curious to know what others do, thought that was the idea of a forum ?

I was misled by the word "should" - it seems that you meant to ask "do", or "would", in which case my personal answer is heat shrink sleeving (if I don't forget to put it on the cable ), otherwise self-amalgamating tape.

 

[Adam_151]

A 9k5 shower on stage 1 heating will probably not trip a 32A breaker on a 6mm cable

Eh? A non-faulty 9.5kW shower, even on full chat, will definitely trip a 32A breaker, even on 1mm² cable.

According to the curves on page 199 of the regs, a 32A type B will not trip for >10000 seconds at 41A, so I'm interested to know the basis of this statement.

Indeed, 41A is a 28% overload of the 32A breaker, which is well below the 45% overload which has to trip to trip it, so its firmly in the region of an overload which can be tolerated for a small while, and looking at the curves backs this up* (the 45% comes from where the aging equation for pvc breaks down, and instead of just running hotter and ageing faster, the cores start to slice through the pvc on bends etc until the breaker ends up opening very fast indeed )

Of course its bad practice to design a circuit that we know will be overloaded, but we do recognise that it might happen once in a blue moon when we use diversity (the mobile disco plugging into the nearest available ring final circuit for example when its already loaded)


*although the curves will be worst case that the breaker standards allow and in reality most will be better, I reckon its safe to assume that if you use the shower for a reasonable amount of time rather than try and wash yourself away to nothing, then the breaker is unlikely to trip