Bend 90°?: 1.33" thick power cable with 7" length from wall?

[Tobias Claren]

Hello.

Is it allowed to turn a 1.3" (34mm) thick 4-core (neutral and 3 phase) cable that is 7" (18cm) long, including outer insulation, at the exit from the wall by 90° like a clock hand?
If the insulations are too stiff, I could heat the piece of cable with a hair dryer.

This black cable is certainly very rigid.
It should not be damaged. This is the house connection before the official House Connection Box.
It is forbidden to open the sealed box.
But I want to move the box from 3 o'clock to 6 o'clock, and put all other parts under the stairs.
Away from the wall of this basement vestibule.
Previously, there hung a wrought iron coat rack with mirror.
There's a couch underneath it.
The basement vestibule is not really an "inhabited space", but a living space.
Heating, couch, and in the past, a TV (and perhaps again).

After turning 90° downwards, I can screw the meter cabinet to the wall to the left of the wall from which the black cable comes.
The ripple control receiver for switching off the solar feed into the grid (the grid operator must still pay), then i can then also easily move.
This is the box above the House Connection Box.
The small distribution box between the House Connection Box and the meter cabinet connects the power output of the meter cabinet with the old cable to the old meter cabinet 3m further to the right.
I may want to replace that completely with some thicker cable.


Thanks.

 

[snowhead]

NO you can't safely turn the cable downwards, you will most likely damage it and yourself.
The cable looks like it probably belongs to your Power / Energy supplier, only they could move it.
And depending on the age of the cable your Power supplier may want to install a new cable instead of turning it down.

To be able to safely turn the cable it will need disconecting from the House connection box, so that will mean also disconnecting the power onto that cable from wherever it originates.
When the cable is turned the 4 cores will move inside the cable.

If the cable is turned it will need testing to prove the insulation has not been damaged.

 

[Tobias Claren]

It is from 1974, 49 years old.

So it remains:
* Mount the Meter Cabinet horizontally under the Home Connection Box :-/ .

* Possibly normal upright directly to the right of the Home Connetion Box.
Then I have to "stow" the cable underneath.
The cable that comes out of the Home Connection Box is not an absolutely flexible cable, but the individual wires are not just one solid 16mm² core either. Each wire consists of 7 or 8 smaller solid wires.
The solar inverters come to the other wall on the left directly above the floor.
The meter cabinet would also be more easily accessible.
But the solar cables would probably not be long enough.
I would have to extend them. E.g. with insulated crimp connection sleeves.

"Maximum amps for power transmission":

AWG 7 (10,6mm²) = 30A
AWG 5 (16.8mm²) = 47A

Really?
For the three-phase connection from meter outlet to sub-distribution?

Other website says (translated):
Common cables for residential sub-distribution boards with normal cable lengths and back-up fuses up to approx. 50A are, for example, NYM-J 5x10mm2. For apartment distributors with back-up fuses (e.g. with SLS switches) with 63A and/or longer cable runs and/or with electric hot water preparation, a NYM-J 5x16mm2 if both factors apply at the same time, possibly also a NYM-J 5x25mm2 cable.

There it is 10mm² up to 50A, and 16mm² up to 63A.
Why this difference? Other voltage or phases?
Here usual RCD sizes are 40A (AWG 7 / 10mm²) or 63A (16mm²).
There are also 100A RCD.
I am considering replacing the in-wall cable with ~11.5ft (3.5m) length, and probably 10mm² (AWG ~7) cross-section with at least 16mm² (AWG ~5).

If there is only 16mm² coming out of the home connection box, it probably won't do any good to run more there.
Unless i ask the licensed electrician to replace the piece later.
But I don't know how many amps the house connection can handle.
Do you know what cross-section the 4-core black piece of cable has?
Maybe 25mm² (AWG ~3 [26,7mm²]).
Or (diameter of the bare conductor):

• 35mm²: (0.26" / 6.7mm)
• 50mm²: (0.31" / 8mm)
• 70mm²: (0.37" / 9.4mm)
• 95mm²: (0.43" / 11mm)
• 120mm²: (0.49" / 12.4mm)

etc..


Currently installed three-phase consumers:

• Stove + oven (max. ~7.5kW?)
• Instantaneous water heater in the bathroom (21kW)
• Instantaneous water heater in the kitchen (27kW)
• Dishwasher (9,6kW)

Even if I run both instantaneous water heaters at the highest level, the 40A RCD never tripped until now.
The test button works though.
21kW + 27kW are 48kW. That is (is it true?) ~70A (3 phases = 400V).
Maximum flow of cold water into the instantaneous water heater in the kitchen ~11.7l/min.
Maximum cold outflow in the bathroom at the bathtub 15l/min.
Maximum hot outflow from the instantaneous water heater in the bathroom 5,8l/min (has a flow indicator).

 

[ipf]

You're not going to get any decent advice about that lot on a forum.
You need an experienced, qualified electrician involved......a German one.

 

[MJPD29]

Out of interest, why does the conduit stop short of every corner? Did the installer not know how to bend it? Or is that how it is commonly installed? Kind of defeats the purpose of it

 

[pc1966]

Out of interest, why does the conduit stop short of every corner? Did the installer not know how to bend it? Or is that how it is commonly installed? Kind of defeats the purpose of it

That seems common in Germany, they seem to use plastic conduit more like cable clips than containment as all the cases like that I saw on my trips were already over-sheathed stuff (i.e. not singles like UK conduit typically contains).

 

[Lucien Nunes]

why does the conduit stop short of every corner?

use plastic conduit more like cable clips

Yes, this is standard German practice. The cable is NYM-J or similar and quite suitable for being clipped to the surface, but a popular method of support is to thread lengths of straight conduit onto it and fix those instead. It would be difficult or impossible to pull the cable round bends with the conduit pre-installed.

"Maximum amps for power transmission":
AWG 7 (10,6mm²) = 30A
AWG 5 (16.8mm²) = 47A

These figures are too low for copper cable in normal situations. There is no one single current rating for a cable, it depends on temperature, installation method etc. But such low figures would only apply where many cables are run together or within thermal insulation.

21kW + 27kW are 48kW. That is (is it true?) ~70A (3 phases = 400V).

Yes, that is correct.

Even if I run both instantaneous water heaters at the highest level, the 40A RCD never tripped until now.

RCDs (FI-Schalter) do not trip on overload or short-circuit, only leakage (differential) current. The 40A rating is the maximum current rating, not a tripping threshold. A miniature circuit breaker (LS-Schalter) will trip on overload, as will an RCBO (FI/LS-Schalter).

A 40A RCD will be overloaded, and possibly damaged, by use at 70A load but will not trip. I suspect it was there before the instantaneous water heaters were fitted and has not been upgraded to suit them. A review of the installation and whether the supply needs increasing, would seem a priority.

Is it allowed to turn a 1.3" (34mm) thick 4-core (neutral and 3 phase) cable that is 7" (18cm) long, including outer insulation, at the exit from the wall by 90° like a clock hand? If the insulations are too stiff, I could heat the piece of cable with a hair dryer.

The cable and box are the property of the electricity supply company and their own rules and perhaps your contract with them, if nothing else, almost certainly prohibit anyone but their authorised technicians from altering them. On a practical note, when a large cable is rotated, the conductors tend to slide over each other inside and some try to pull away from the nearest end and others push towards it. If this loosens the connections inside the box, they could overheat under heavy load. If a short-circuit occurs in that cable the arc-flash can be dangerous as the loop impedance is very low and the protection maybe 200-400A fuses in the supply network.

As an electrician in the UK, I would not interfere with this cable and would request any changes to be carried out by network operator.

 

[grumpyjohn01]

The cable is NYM-J or similar

As a fan of NYY-J cable for outdoor applications that don't require armour this stuff looks like it could be handy for larger sizes within buildings as according to the specs min bending radius is 4 x cable diameter, any reason we shouldn't use it in the UK? I have to admit when calculating cable sizes with NYY-J to using tabulated values for T&E and then SWA and making a call..naughty I'm sure.

 

[Lucien Nunes]

I don't see anything wrong with using NYM-J in the UK as it can be appproved to a UK recognised standard BS EN 50265-2-1, and there is a corresponding LSZH version. A number of UK wholesalers stock it too, but I usually bring mine back from Europe, which admittedly doesn't carry the BS EN marking specifically. Presumably it would if you bought it from Batt or Cleveland or even CEF stock it.

Until recently there was a coil of 5G2.5 and another of 3G1.5 stashed under my sideboard since my last trip to Estonia. Sheds have large drums on the shelves and you can just reel off the length you want through a measuring roller. Roll ends are put in bargain bins at reduced prices. Or you can buy pre-packed rolls.

After I first started experimenting with it in the 1980s, when I would come back from Germany with my suitcase full of electrical fittings, I started to find T+E slightly naff and I've thought that ever since. But as I so often say, no one country's system has all the best bits.

NYM and KH05 wind-down station and pre-packs at Bauhaus: