5 core SWA 120mm pvc cable

[davesparks]

I have - he recommended Kew and i rang them
My client is old and not tech savvy and so i am helping him. He also does not have much money and so I am trying to get him the best price (as this size cable is going to be expensive).
Understandably the Sparky who is doing the install does not want to buy the cable so he has put that into the clients court and will therefore be working on day rate to connect etc

...…...just hoped to have some more input
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Hi BuzZ its 5 core SWA 120mm pvc cable

It's difficult to comment without knowing more details, but I would ask the person who calculated the cable size whether they have considered parallel cables to reduce the overall size an dtherfire price?
Also using 5 core seems a little bit odd, especially in that size.
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Have you tried pricing up 500m of 70mm 5 core SWA and comparing the prices?

Why 70mm? 2x50mm would normally replace 1x120mm

 

[buzzer123]

I no spoon why 5 not 4 just asking three phase and all.

People are questioning that you don’t need five core & you can go with 4 core
I assumed one was For neutral and the other was for earth and the three remaining were for the phases am I right or am I talking to a complete lemon electrician?

 

[Spoon]

It's difficult to comment without knowing more details, but I would ask the person who calculated the cable size whether they have considered parallel cables to reduce the overall size an dtherfire price?
Also using 5 core seems a little bit odd, especially in that size.
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Why 70mm? 2x50mm would normally replace 1x120mm

You are correct mate.

@buzzer123, as @davesparks has pointed out. 2 x 50mm cab replace your 1 x 120mm

 

[davesparks]

People are questioning that you don’t need five core & you can go with 4 core
I assumed one was For neutral and the other was for earth and the three remaining were for the phases am I right or am I talking to a complete lemon electrician?

It's not always a simple yes or no answer. Without knowing the details of the design and calculations for the circuit it is hard to know whether 4 or 5 core is required.

I'm going to put this in somewhat simplified terms as I get the impression you aren't necessarily interested in the full technical explations and terminology.
Generally with armoured cable the four cores are three lives and a neutral, the armour itself is the earth. However in some situations the armour doesn't satisfy the requirements for being the earth (particularly if it is doing earthing and bonding, not just earthing) this is worked out based on a few calculations and the details of your particular incoming supply.

This cable will have been oversized to account for the long distance it has to travel, and to be honest I'm a little surprised that it isn't bigger than 120mm for that distance. This will generally mean that the armour will be big enough to be both an earth and a bond.

Ypu may not be talking to a complete lemon, but they may not have a full understanding or much experience at designing this type of circuit.

 

[westward10]

Allowing a 2% vd you will scrape 80A on a 240. A 300mm will give you 90A.

 

[davesparks]

Allowing a 2% vd you will scrape 80A on a 240. A 300mm will give you 90A.

I had a feeling 120 would be cutting it a bit close, my guess would be they are planning for a 63A circuit.

 

[westward10]

I had a feeling 120 would be cutting it a bit close, my guess would be they are planning for a 63A circuit.

You would need 185 for 63A.
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45A is about the limit for a 120 and 2%vd.

 

[buzzlightyear]

Me my self is not questioning what cable that he is using knowning the fact the op sould be asking the said spark i agree what some are saying
Its like asking is this string long enough.

 

[buzzer123]

Hello all
Thanks for your responses.

I believe that is 100 A total Split across three phases.
Client is talking to UK power networks about upgrading transformer to have 100 A from each phase.

What size cable would he need to future proof for that?
Thank you.

 

[buzzlightyear]

Op should you not ne asking you spark that qestion.