Safe solution of having a cu 10 meters away from meter

[Rob_the_rich]

Yes, but that force is spread uniformly over the entire cable length, from origin to source of fault. 

Ah, so even if the fault is at the origin of the consumer's installation, it includes all the distribution cable back to the Tx. Makes sense.

 

[Rob.]

Ah, so even if the fault is at the origin of the consumer's installation, it includes all the distribution cable back to the Tx. Makes sense.

https://www.youtube.com/embed/kHotp7mpO-g?feature=oembed

 

[Sharpend]

Do you think that's why the LFB insist on metal ties/cable restraint on exits! :innocent  

 

[Tony S]

I’ve just upset the septics not ten minutes ago.

Is that how the cables will be held?

If so you may want to carry out this calculation

Ft = (0.17 x Ip²)/S

Where
Ft = Maximum Force per unit length of cable (N)
Ip= Peak short circuit current (KA).
S = Centre to centre distance between neighboring conductors (m)

 

[steptoe]

What was the contention about the earth being separate??

A cpc is SUPPOSED to pass through the same hole as the live conductors in a ferromagnetic enclosure, but mine does not, and nobody has ever noticed......

john...

I think it was @Sidewinder that wasn't completely happy with it,

OK, so this is where I am at a loss tbh,

The armour of the SWA is properly flanded to the metal box, there is an earth lugged to the box going to the MET, there is a core if the SWA used as an earth that passes through a gland in the box going to the MET also, if the actual box is earthed, why does it matter if an additional earth passes through it,?

I could omit said earth completely and solely use the armour with is connected to the MET via the box an lugged earth, why does the additional earth make a difference,?

Maybe I'm missing some fundamental basic thing here, but I really don't get it,

I'll take a picture when I get home. 

 

[Sidewinder]

As has already been said, there can be issues with the cpc through a separate hole, and there is a reg, it is worded something like collectively surrounded by ferrous material?

I'd have to look it up, but if anyone wants to search then feel free!

I'm a tad busy at the mo with PUWER stuff.

 

[NozSpark]

 

[Sidewinder]

Well done Noz!

So this:

521.5 A.C. circuits: electromagnetic effects

521.5.1 Ferromagnetic enclosures: electromagnetic effects

The conductors of an a.c. circuit installed in a ferromagnetic enclosure shall be arranged so that all line conductors and the neutral conductor, if any, and the appropriate protective conductor are contained within the same enclosure.

Where such conductors enter a ferrous enclosure, they shall be arranged such that the conductors are only collectively surrounded by ferromagnetic material.

These requirements do not preclude the use of an additional protective conductor in parallel with the steel wire armouring of a cable where such is required to comply with the requirements of the appropriate regulations in Chapters 41 and 54. It is permitted for such an additional protective conductor to enter the ferrous enclosure individually.

521.5.2 Single-core cables armoured with steel wire or steel tape shall not be used for an a.c. circuit.

NOTE : The steel wire or steel tape armour of a single-core cable is regarded as a ferromagnetic enclosure. For single-core armoured cables, the use of aluminium armour may be considered.

 

[Tony S]

521-5-2 Thanks Noz  X(

Guess what I’ve missed out of knowledgebase, &%^$£*!

 

[Rob_the_rich]

SW am I on your ignore list? I posted that first reg number in post 14 :C

Tony S, induced voltages on the armour of single core swa/awa would be my guess.

 

[Sidewinder]

SW am I on your ignore list? I posted that first reg number in post 14 :C

Tony S, induced voltages on the armour of single core swa/awa would be my guess.

Rob,

Sorry, I didn't see it!

 

[Rob_the_rich]

Rob,

Sorry, I didn't see it!

no worries

 

[Sidewinder]

no worries

I've scoobed you to make up for it!

 

[Tony S]

SW am I on your ignore list? I posted that first reg number in post 14 :C

Tony S, induced voltages on the armour of single core swa/awa would be my guess.

You got it, sheathed singles both lead and aluminium = circulating currents.

 

[Risteard]

does the inner covering of SWA count as a cable 'sheath'?...just wondering , serious question

No. That isn't its design intent and therefore it should not be used as such.