:) / 4x300 mm2 SQ.PVC/XLPE

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Hatim

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Is it logical to use 95 mm2 SQ.PVC/XLPE (Yellow Green) alongwith 4x300 mm2 SQ.PVC/XLPE cable from MDB to SMDB.
 
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Hatim said:
Is it logical to use 95 mm2 SQ.PVC/XLPE (Yellow Green) alongwith 4x300 mm2 SQ.PVC/XLPE cable from MDB to SMDB.
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I'm neither going to take a calculator to your numbers nor sort out your acronymns.

If you actually want some help perhaps you might rephrase.
 
No Mr. Hatim. Follow minimum required c.s.a for Earth Continuity Conductor as per standard. Use 1x150 sq.mm cable.

Musthafa
 
Cable from MDB to SMDB

Cable from MDB to SMDB

Is it logical to use 1 x 95mm2 (yellow green) alongwith 1 x 300 mm2 XLPE Cable.

See the situation is that we want to feed sub main distribution board from main distribution board. The main feeder is 4 x 300 mm2 XLPE/PVC from MDB to SMDB. However, the designer laid 1 x 95 mm2 (yellow green) alongwith the feeder cable which is 4 x 300 mm2 XLPE/PVC.

Ain't the size of the yellow green (earthing cable) not more then usually required & what should be the correct size of yellow green (earthing cable) alongwith 4x300 mm2 x LP/PVC.

Kindly reply with references (if possible).
 
physis said:
I'm neither going to take a calculator to your numbers nor sort out your acronymns.

If you actually want some help perhaps you might rephrase.
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Why rephrase? If you don't understand nomenclature of other countries, perhaps next time you may want to sit on the sidelines and learn.:rolleyes:
 
Given the use of sqmm for CSA I'm going to assume this is something covered under the UK wiring regs (or something vaguely European), and under the UK regs you are required to use your noggin and test equipment, rather than use a table and follow a rule.

This wiring arangement is often seen where SWA cable is used; you can use the steel wire armour for the earth conductor, but many times it has an unacceptably high impedence so a single core additional earth cable is also run, which is effectively in parallel with the armour of the SWA. Note that this isn't NEC style parallelism with identicalish conductors and lengths, its an unequal parallelism.

The test for acceptable earth impedence is if you bolt short the downstream panel to earth will the upstream breaker open within the prescribed time? If it will then life is sweet. If not, then option one is you need to reduce the earth impedence so that the breaker will open in the prescribed time, and this is where the parallel earth wire comes from. Note that you dont actually bolt short the thing to find out; you use a test meter that measures prospective short circuity current and then consult the breaker curves.

Option two is to install a RCD.

I hope I'm remembering all this correctly, it's now years since I was in the UK...
 
Hatim said:
Is it logical to use 95 mm2 SQ.PVC/XLPE (Yellow Green) alongwith 4x300 mm2 SQ.PVC/XLPE cable from MDB to SMDB.
Click to expand...

I suppose I should apologise, I've never seen terminology anything even close to this, and I've seen a lot of stuff. None the less, it appears I'm ignorant with regard to your question.
 
Cable from MDB to SMDB

Cable from MDB to SMDB

dbuckley said:
Given the use of sqmm for CSA I'm going to assume this is something covered under the UK wiring regs (or something vaguely European), and under the UK regs you are required to use your noggin and test equipment, rather than use a table and follow a rule.

This wiring arangement is often seen where SWA cable is used; you can use the steel wire armour for the earth conductor, but many times it has an unacceptably high impedence so a single core additional earth cable is also run, which is effectively in parallel with the armour of the SWA. Note that this isn't NEC style parallelism with identicalish conductors and lengths, its an unequal parallelism.

The test for acceptable earth impedence is if you bolt short the downstream panel to earth will the upstream breaker open within the prescribed time? If it will then life is sweet. If not, then option one is you need to reduce the earth impedence so that the breaker will open in the prescribed time, and this is where the parallel earth wire comes from. Note that you dont actually bolt short the thing to find out; you use a test meter that measures prospective short circuity current and then consult the breaker curves.

Option two is to install a RCD.

I hope I'm remembering all this correctly, it's now years since I was in the UK...
Click to expand...

:) thanks a lot for your help.

We have RCD in our main breaker....
 
Hatim said:
Is it logical to use 95 mm2 SQ.PVC/XLPE (Yellow Green) alongwith 4x300 mm2 SQ.PVC/XLPE cable from MDB to SMDB.
Click to expand...

Just to be sure; you are asking questions about materials and designs that are obviously NOT ANSI designations and do not fall under the perview of the NEC or installations according to those requirements outside of the US. This forum is dedicated to those issues.
 
weressl said:
Just to be sure; you are asking questions about materials and designs that are obviously NOT ANSI designations and do not fall under the perview of the NEC or installations according to those requirements outside of the US. This forum is dedicated to those issues.
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Citation?:smile:
 
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