30Amp connector strip suitable for 32A 4mm Radial?

[eveares]

It seems that the connector strip sizes do not follow the mcb rating sizes.

So if you were working on a 32A 4mm radial and wanted to branch off, if using connector strips would you have to use 60 Amp connector strips or would using 30 amp ones be ok?

I am guessing by the BS7671 regs you would have to use 60 Amp connector strips to support the full 32Amps.

If so, why are 32 Amp connector strips so hard to get in store?

 

[JohnW2]

So if you were working on a 32A 4mm radial and wanted to branch off, if using connector strips would you have to use 60 Amp connector strips or would using 30 amp ones be ok? ... I am guessing by the BS7671 regs you would have to use 60 Amp connector strips to support the full 32Amps.

There is a 'strictly complaint' answer and a 'pragmatic/common sense' answer. You know both of those answers, and have to decide which way to go!

Kind Regards, John

 

[EFLImpudence]

Most connectors seem to have apparently random current ratings.

Ashley J803s are 32A.

 

[JohnW2]

Most connectors seem to have apparently random current ratings. Ashley J803s are 32A.

I'm not so sure about 'random'. Ashley J803s were born long after 6/16/32A MCBs became ubiquitous. Traditional JBs and connector strips etc. mainly have their origins in the days when 5/15/30A fuses were 'all there was'.

Kind Regards, John

 

[EFLImpudence]

Yes, I realise that but you would think they would have been updated - possibly by just changing the number.

However, they and the modern ones like Wago, Click-flow, and Wiska do not seem to relate to conductor CCCs which you (or rather I) would think the relevant factor.

 

[JohnW2]

Yes, I realise that but you would think they would have been updated - possibly by just changing the number.

Oh, yes, I agree with that - particularly since that I doubt that the 'ratings' are much more than 'arbitrary'. Sure, they probably test "30A" ones to make sure that they're OK with 30A flowing, but they'd probably also pass the test with 40A or 50A!

However, they and the modern ones like Wago, Click-flow, and Wiska do not seem to relate to conductor CCCs which you (or rather I) would think the relevant factor.

I don't fully understand what you are saying there. I've often expressed the view that what really matters about terminals (in connectors, accessories or whatever) is their capacity to accommodate and satisfactorily grip conductor(s) (rather than the current which is flowing) - so I think 'CSA(s)-based ratings' are probably more important than 'current ratings'.

Kind Regards, John

 

[EFLImpudence]

What I mean is, for example, Wagos which accept 2.5mm² conductors are rated at 24A (alright for rings, I realise) and those that accept 6mm² are rated at 41A (according to TLC).

I have just thought that the traditional boxes with 3036 ratings must, I presume, allow for the 0.725 derating and so would be satisfactory with slightly higher rated MCBs.

 

[JohnW2]

What I mean is, for example, Wagos which accept 2.5mm² conductors are rated at 24A (alright for rings, I realise) and those that accept 6mm² are rated at 41A (according to TLC).

Oh, I see. Yes, that's a little odd. I'm not actually sure that "24A (alright for rings I realise)" is necessarily true. Just because the regs require a minimum CCC of 20A, that doesn't mean that it has to be that low (in fact, rarely will be), and all the regs require is that the circuit be designed to as to minimise the changes of any of the cable being overloaded for long periods. It's therefore quite possible that, with clipped-direct 2.5mm², a ring could be designed to potentially have sustained currents up to 27A in some of the cable

I have just thought that the traditional boxes with 3036 ratings must, I presume, allow for the 0.725 derating and so would be satisfactory with slightly higher rated MCBs.

I'm not so sure about that. You're talking as if JBs etc are 'rated' in the same way as cables, in a manner which is OPD dependent, and that may well not be the case. In other words, when a JB says that it is 'rated at' 30A, that might actually be saying that the maximum current is 30A, rather that the maximum current is that which a 30A fuse would allow to flow.

Kind Regards, John

 

[EFLImpudence]

I'm not actually sure that "24A (alright for rings I realise)" is necessarily true. Just because the regs require a minimum CCC of 20A, that doesn't mean that it has to be that low (in fact, rarely will be), and all the regs require is that the circuit be designed to as to minimise the chances of any of the cable being overloaded for long periods. It's therefore quite possible that, with clipped-direct 2.5mm², a ring could be designed to potentially have sustained currents up to 27A in some of the cable.

Whilst that could happen, I don't think it should be designed that way.

I'm not so sure about that. You're talking as if JBs etc are 'rated' in the same way as cables, in a manner which is OPD dependent, and that may well not be the case. In other words, when a JB says that it is 'rated at' 30A, that might actually be saying that the maximum current is 30A, rather that the maximum current is that which a 30A fuse would allow to flow.

Oh, - I don't know - but if that is correct then the JBs would all be rated less than the cables have to be and negates your relating them to the fuse values.


As you say, if the terminals connect the conductors satisfactorily so that no current actually flows through them (unlike other types) then what do the current ratings signify?

 

[JohnW2]

Whilst that could happen, I don't think it should be designed that way.

If it's OK to design a ring with 20A CCC cable such that it's unlikely that that the current will exceed 20A for long periods, I don't see why it's wrong to design a circuit with 27A CCC cable such that it's unlikely that the current will exceed 27A for long periods - by my reading of the regs, it's certainly 'compliant'. In any event, 'design' of a sockets circuit is a crytstal ball job, anyway, since one can but guess what is likely to be plugged into which socket.

Oh, - I don't know - but if that is correct then the JBs would all be rated less than the cables have to be and negates your relating them to the fuse values.

I don't know, either, but it's far from beyond belief that a '30A rating' means 30A maximum current.

As you say, if the terminals connect the conductors satisfactorily so that no current actually flows through them (unlike other types) then what do the current ratings signify?

As we've both said, when multiple conductors go into the same terminal (as in accessories), then a 'current rating' for the terminal makes no real sense (hence my belief that 'CSA accommodating capacity' is what actually matters). In the case of connector blocks (if conductors are inserted into 'different sides') or Wagos etc., when there is just one conductor per 'hole', things are different, since the full current then has to flow through part of the connector - which one would therefore expect to have a 'current rating'.

Kind Regards, John

 

[kai]

It should be fine, as the 30amp rating is a NOMINAL rating, so their use on a 32amp ring final circuit should be OK, remember any single socket on the ring will be of a 13amp rating too.

 

[JohnW2]

It should be fine, as the 30amp rating is a NOMINAL rating ....

Who said that ... and, if someone said it, what does it mean?

... remember any single socket on the ring will be of a 13amp rating too.

Some believe that all BS1363 accessories have terminals designed/rated to be able to carry 32A (whatever that means, given that little of the 32A, even if the circuit were 'fully loaded' would go through the material of the terminal).

Kind Regards, John

 

[ban-all-sheds]

Yes, I realise that but you would think they would have been updated

The Ashley one you mention has a rating of 32A. Is that outdated?

possibly by just changing the number.

Indeed.

And in the absence of any BS, or equivalent formal standard, for the testing and verification of an accessory's current carrying capacity, we just have to hope that there was more behind any change than some spotty youth with a keyboard, a mouse, and a global find/edit tool.

 

[EFLImpudence]

The Ashley one you mention has a rating of 32A.

I also mentioned that - thinking the OP could use one if he were worried about the connector block.