UK Terminating parallel supply

[DNS1]

Need to use a pair of 6mm T&E in parallel to run an 10.8kW electric shower. Both same length and same route, will be joined to a single 10mm at the load end, and protected accordingly.

Can anyone recommend a terminal box which I can use for this?

I don't fancy putting a pair of 6mm into one side of a 50A chocbloc, but something like a Henley seems a bit OTT...

 

[Marvo]

They both go into the wall at the same place and come out in the loft at the same place. They were installed at the same time and are pretty much the same when metered, so I'm confident they're on the same route.

Did you test the L+N resistance of both cables? What were the results/how big is the difference?

 

[Pete999]

I'm with you, M...but here's a question.
Would they be classed as maintenance free?

Will the box be accessible?

 

[DNS1]

Did you test the L+N resistance of both cables? What were the results/how big is the difference?

Can't remember the exaxt results, but the difference between them was negligible.
[automerge]1584008444[/automerge]

https://04646a9cf351cc0d3888-b8b406d15fe93f790abb5bf0e9ab7ab3.ssl.cf3.rackcdn.com/downloads/product/ideal_wire_connectors_datasheet_de5276908eda8b6d0edb8c191a404c4a.pdf?1532419793

Anyone used these before?!

 

[davesparks]

Anyone used these before?!

The push fits I've used, they arent as good as wago in my opinion.

The fire nuts I wouldn't touch and I don't think any self respecting electrician would.

 

[pc1966]

The push fits I've used, they arent as good as wago in my opinion.

The fire nuts I wouldn't touch and I don't think any self respecting electrician would.

The example push-fit are only to 2.5mm stranded anyway, Wago do to 6mm in leaver for sure, but I think the OP needs to attach to 10mm eventually.

Agree on the fire nuts!

The big 100A Henley style blocks seem overkill, I would generally use DIN rail stuff as you can get jumper bars to common them (so using two DIN terminals gives 4 connection points), and the earth style DIN terminals also ground to the rail itself.

Look on CEF for IVBWKN10-10 (10 way jumper bar, can be cut down as needed) and WKN10U (grey terminal) and WKN10U BLUE (same, but blue if you feel the need to colour code them for neutral). One jumper bar and 6 terminals would do each end.

If using the WKN10SLU earth terminals to common earth via the rail, then one 10-way jumper bar would do both ends (need 4 links of 2 terminals, so 8 from the bar).

 

[stevethesparks]

I think its Ashley that do a large brown 60 Amp jb, I'm sure that would accept all the conductors you require to join.

 

[pc1966]

I think its Ashley that do a large brown 60 Amp jb, I'm sure that would accept all the conductors you require to join.

Yes, much easier than DIR rail!

A quick search on CEF shows "Scolmore Click 60A" box apparently takes up to 25mm cable so should do the job in a much simpler and cheaper way. No idea it if could be considered "maintenance free" to be hidden though, I doubt it given the screw terminal fixing method.

 

[telectrix]

or terminate the 2 x 6mm into shower isolator (in), then 10mm from there (out) to shower.

 

[DNS1]

or terminate the 2 x 6mm into shower isolator (in), then 10mm from there (out) to shower.

I was thinking about it, but assumed I'd have a massive ballache getting them into the terminals

 

[Lucien Nunes]

For general paralleling and commoning duties where screw terminals are suitable, I often use European-style commoning blocks such as the Cembre range. Here's another Italian example - I've used these and they are well made and substantial. The particular type in this link has four entries for up to 6mm² and two for 6-16mm² and can be mounted to a DIN rail with a clip.
6-16mm² commoning block from RS

Here is another style from Legrand that clips directly onto the rail. These are good too although lack the support of the entry spout to prevent cable movement in the terminal.
4-way Legrand 16mm² commoning block

Personally, I would not try terminating two conductors in a shower isolator for the purpose of paralleling. The regs and common sense require the paralleling connection to be made in such a way that it is unlikely for the continuity to be lost. We are all familiar with terminal burnouts, due to high resistance contacts and cables coming loose with manoeuvring the switch into place, so I venture that putting the two into the isolator terminals doesn't really meet that criterion.

 

[pc1966]

For general paralleling and commoning duties where screw terminals are suitable, I often use European-style commoning blocks such as the Cembre range. Here's another Italian example - I've used these and they are well made and substantial. The particular type in this link has four entries for up to 6mm² and two for 6-16mm² and can be mounted to a DIN rail with a clip.
6-16mm² commoning block from RS

Here is another style from Legrand that clips directly onto the rail. These are good too although lack the support of the entry spout to prevent cable movement in the terminal.
4-way Legrand 16mm² commoning block

Personally, I would not try terminating two conductors in a shower isolator for the purpose of paralleling. The regs and common sense require the paralleling connection to be made in such a way that it is unlikely for the continuity to be lost. We are all familiar with terminal burnouts, due to high resistance contacts and cables coming loose with manoeuvring the switch into place, so I venture that putting the two into the isolator terminals doesn't really meet that criterion.

Interesting to see that RS part, never know about it so thanks!

As well as the one you linked to with 4 * 2.5-6mm and 2 * 6-16mm holes, RS also stock a 4-way common block with 4 * 6-16mm that is cheaper (but in packs) as:

RS PRO Commoning Block, 4 Way, 450 V | RS

uk.rs-online.com

I also don't like the idea of using the isolator's terminals. At least some of the junction boxes allow the cables to be clamped as they enter for support, and conductors terminated with double-screws for greater reliability.