Joining 6mm

[EFLImpudence]

Yes, but there is room for eight cables - grouping?

 

[JohnW2]

Yes, but there is room for eight cables - grouping?

Where on earth did "eight cables" come from? - there's only provision to terminate 4 conductors in each of the terminal blocks.

Kind Regards, John

 

[Echo the husky]

It's probably good to try to stop the MF JBs overheating, they don't seem to like heat. The MF JB was heated gently with a small flame from a gas torch, the round one was blasted for a substantial time with the flame at full power. The MF one although fairly heat resistant ignited, but self extinguished after giving off lots of stinking black smoke, the round one I could not ignite and it only scorched.
Sorry for the blurry pics!

 

[EFLImpudence]

Where on earth did "eight cables" come from? - there's only provision to terminate 4 conductors in each of the terminal blocks.

There's room for two cables at each clamp (five cables can be fitted in 501s).
I know there aren't enough conductor terminals but ...



Just thought, is that why they are 501 and 803/4?

 

[JohnW2]

It's probably good to try to stop the MF JBs overheating, they don't seem to like heat. ...

That I would not dispute. However, as I keep saying, if there were a risk of "overheating" (particularly to the extent of damaging the enclosure) as a result of current through the sprung terminals, then I would be very worried about the adequacy of those terminals.

Indeed, all we are debating (in response to my question) is adding a terminal block accommodating four further conductors to a JB which already was accommodating 2 x 4 live conductors (L and N) in terminal blocks identical to the 'additional' one - and I personally find it hard to believe that such would necessitate reducing the rating from 32A to 20A.

Do you really expect terminals joining cables carrying 32A to get even remotely hot (even 'warm') ??

Kind Regards, John

 

[Echo the husky]

not at all, I might have to shove 32A through a new pair and peer at them with the thermal imaging camera. Unless anyone else wants a go. A flex melted into the carpet last time I was messing around.

 

[JohnW2]

I know there aren't enough conductor terminals but ... Just thought, is that why they are 501 and 803/4?

I can't answer the question about the origin or meaning (if any) of the product numbers, other than to say that it would make absolutely no sense for it to mean that they are designed for 8 cables (even though 8 cables would fit in the clamps) - since, if one had 8 cables, half of the conductors would have 'nowhere to go'!

Kind Regards, John

 

[EFLImpudence]

since, if one had 8 cables, half of the conductors would have 'nowhere to go'!

I think you'll find I said that in my last post.

 

[JohnW2]

not at all, I might have to shove 32A through a new pair and peer at them with the thermal imaging camera.

Quite. Unless your thermal imaging camera is pretty sensitive, I suspect that you might struggle to see any temperature rise at all (let alone any rise that could conceivably damage the JB), even if it were buried in insulation. If the terminals are even half decent, I would also suspect that the same would be true for currents appreciably higher than 32A.

Kind Regards, John

 

[JohnW2]

I think you'll find I said that in my last post.

You did, and I quoted it ... which is why I don't understand why you seem to be suggesting that the '8' of the product number might mean that it was designed to be used with 8 cables!

Kind Regards, John

 

[Echo the husky]

There must be some reason why it says in big letters not to cover with thermal insulation.

 

[333rocky333]

It's probably good to try to stop the MF JBs overheating, they don't seem to like heat. The MF JB was heated gently with a small flame from a gas torch, the round one was blasted for a substantial time with the flame at full power. The MF one although fairly heat resistant ignited, but self extinguished after giving off lots of stinking black smoke, the round one I could not ignite and it only scorched.
Sorry for the blurry pics!
View attachment 105813 View attachment 105814

The ones sold round here have all "white" terminals
Is that an old first edition one
The newer ones seem to have an install leaflet

 

[securespark]

strip..., push it in hard and you can't go wrong. Give it a good tug...

Oooh, Matron!

 

[JohnW2]

There must be some reason why it says in big letters not to cover with thermal insulation.

Possibly, at least in their minds, but that good reason could be that it sounds like a good way of protecting their backsides. Maybe I'm wrong, but I really would not have thought that the terminals of any sort of JB carrying 32A through each of three sets of terminals should get even remotely warm/hot, even if deeply buried in insulation.

Of course, if the JB were buried in insulation, then at least some of the cables also would be - but that's as true of 'just cables' as it is of cables in/around a JB.

Kind Regards, John

 

[John D v2.0]

Quite. Unless your thermal imaging camera is pretty sensitive, I suspect that you might struggle to see any temperature rise at all (let alone any rise that could conceivably damage the JB), even if it were buried in insulation. If the terminals are even half decent, I would also suspect that the same would be true for currents appreciably higher than 32A.

Kind Regards, John

I thought thermal imagining cameras were designed to be sensitive, so you can see for example where the heat is leaving your house?
Also there must be heat generated under high load in the cables let alone the connections as copper has a good resistance and we only limit it to 70c in PVC. If it didn't heat up how would screw terminals on cooker circuits loosen themselves.