Isolated cable bifurcation

[asalcedo]

How do I connect two cables to each phase of a circuit breaker if the dimensions of the cables exceed the space available in the circuit breaker?

I need to install a Voltage Surge Suppressor at the entrance of the house (against lightning)

This has to be done in parallel

I have triphasic 230V supply

The problem that I encounter is that the present cables take up almost all the space available in the metallic receptor in the circuit breaker.

The width of the metal crimp terminating the supply cables is 9mm (picture 1)

I plan to run 25mm2 cables to the voltage suppressor (picture 2)

I have tried to source locally some kind of bifurcating cable end but have not found it.

Since what I need to do is not unusual I feel that there should already be some kind of standard solution.

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[Tim Watts]

Is the voltage suppressor single ended or does it go in series with the supply?

[spuorgelgoog]

I would use the sort of double-wire to circuit breaker ferrules used for parallel connection of supply to multiple RCDs on CUs.

Owain

[meow2222]

Seldom is that useful

Crimp-on pointy things or downsize the cable. I won't ask why the big stuff.

NT

[Mike Tomlinson]

En el artículo , [e-mail] escribió:

You didn't look at the OP's photos, did you?

[spuorgelgoog]

No. This is Usenet :-)

But having looked at the photos I would still use the ferrules for taking 2 x wires into 1 x terminal, as are shown in one of the photos.

Other than some Henley blocks tucked in somewhere I don't see any alternative, unless Wagos or similar are available in that size and current capacity.

Owain

[Mike Tomlinson]

;)

As another posted mentioned, whether the surge protector simply sits across the supply, or is installed in series with it, might make a difference to the logistics of installation. The OP's photos aren't clear enough to tell.

Personally, I would want to install it with the shortest possible connection to the main earth terminal, using the thickest cable possible (25mm^2 ?). This would probably mean inserting it in the tails between the meter and the CU.

I also hope the surge unit isn't achieving its earth connection via the DIN rail.

btw, this is classic w_tom fodder, expect him top trip along any second now...

[Graham.]

Would a Spanish poster know what a Henley block is?

[Graham.]

From his IP address the OP appears to be posting from Spain.

Perhaps such things are normal over there.

[Roger Mills]

He would if he asked Google!

[Mike Tomlinson]

En el artículo , Graham. escribió:

I'm in Spain at the moment, and so far I've come across separate socket installations which use a red wire for the earth and green/yellow for the live.

They take an, um, relaxed attitude to lecky over here :)

[spuorgelgoog]

The person who wired up my bathroom fan did that.

At the supply end.

At the fan end the green/yellow was connected to 'earth' (in a surface box, so not connecting to earth, but the faceplate fixing screws on the FCU would have been tingly)

Owain

[harryagain]

There is. A link box.

[Tim Watts]

More relaxed or less relaxed than this?

[asalcedo]

Yes, this is for my house in Spain.

It is in the country side, and has already suffered damage due to lightning in the past.

The surge suppressor is SCHNEIDER Multi 9 ELECTRICAL SURGE ARRESTER

16574

Each phase has to be connected in parallel with the incoming supply and then it is connected to the earth.

I have TT earthing and this suppressor is designed for that.

The optimal placement of the suppressor is where the pictures show since it is the closest to the main earth block, connected to the earth pike nearby.

The electrical installation is done to a very high standard.

I live in London mostly and happen to know a Henley block, which I have under the meter at home.

We have similar things in Spain, but I excluded them because they are too bulky.

I was hoping that there might be something more specific and smaller.

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[Tim Watts]

Perhaps a split load Y tail from another make of dual rcd board?

I have seen them occasionally but they seem rare.

How about crimping some of these on some 10mm2-16mm2 cable:

(I assume the surge arrestor does not need to have the full 25mm2 into it?)

and drop those in with the L1/L2/L3 on the main isolator load side?

(You'll need some heatshrink around the crimped portion)

[asalcedo]

Hi Tim,

You led me to the right solution:

I had read the whole white paper published by Schneider on the matter, but saw no reference to the sectional areas of the cables.

I was thinking that the very high voltages might translate into brief high intensities and thus, it was best to keep the area of the incoming supply cables.

But, your suggestion that the full 25mm2 might not be needed made me look harder for an answer to that question.

It turns out that the leaflet that comes with the actual unit does specify, for all the versions of the surge arrestor (including those designed for much higher lightning frequency areas): "greater or equal to 4 mm2" for the cable lengths involved (those that go from the incoming supply to the surge arrestor and to the earth block)

It does seem that 4mm2 is enough and that is something that I can easily achieve, because I can fit a cable of that size along with the existing supply in the space available in the main isolator

To make the tightening of the cables more uniform and use up less depth I will use 2 x 2.5mm2 cables in each phase stripped bare without any special terminal

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