16mm SWA armour

[gselectrical]

Evening all.

Just a quick one.

Is the armour of 16mm 2-core SWA adequate to use as an earth for a sub main to another DB?

Cheers.

 

[M107]

Yes (46mm csa if steel)

 

[gselectrical]

Yes (46mm csa if steel)

Cheers for the quick reply.

 

[PC Electrics]

Yes it is, but as a Professional Mechanical Engineer I would say this is poor engineering. Your earth connection is entirely dependant upon two hand made mechanical joints, which could suffer from corosion or come loose. If the PVC sheath ever became damaged the armour could corrode away to nothing (I've seen this 3 times in 3 years as a DI). Is it really too much to have a third core to use as cpc?

 

[gselectrical]

Yes it is, but as a Professional Mechanical Engineer I would say this is poor engineering. Your earth connection is entirely dependant upon two hand made mechanical joints, which could suffer from corosion or come loose. If the PVC sheath ever became damaged the armour could corrode away to nothing (I've seen this 3 times in 3 years as a DI). Is it really too much to have a third core to use as cpc?

I see where you are coming from and I have also seen the same, but only on mechanical joints outside. Most seem to be from either incorrect glands used or glands terminated incorrectly.

I am planning on running and terminating this cable within the building. Therefore the mechanical joints would not be liable to damage/corrosion from the weather.

Cheers

 

[spinlondon]

The SWA would be acceptable as CPC, but not as a bonding conductor for PME.

Depending on the size of the main earthing conductor, and by selection from Table 54.8, you may have to use a core in 3 core, a supplementary bonding conductor or increase the size of the SWA and use 3 core.

 

[gselectrical]

The SWA would be acceptable as CPC, but not as a bonding conductor for PME.Depending on the size of the main earthing conductor, and by selection from Table 54.8, you may have to use a core in 3 core, a supplementary bonding conductor or increase the size of the SWA and use 3 core.

Just to clarify, when you say " but not as a bonding conductor" do you mean earthing conductor?

PME system. Main Earth is 16mm.

Cheers.

 

[spinlondon]

Just to clarify, when you say " but not as a bonding conductor" do you mean earthing conductor?PME system. Main Earth is 16mm.

Cheers.

Here's some definitions from the BRB:

"Bonding conductor. A protective conductor providing equipotential bonding."

"Circuit protective conductor (cpc). A protective conductor connecting exposed-conductive-parts of equipment to the main earthing terminal."

"Earthing conductor. A protective conductor connecting the main earthing terminal of an installation to an earth electrode or to other means of earthing."

I'm refering to 'Bonding conductor', as in the definition above.

In your scenario if PME conditions apply, you would need to install at least a 10mm

 

[gselectrical]

Here's some definitions from the BRB:"Bonding conductor. A protective conductor providing equipotential bonding."

"Circuit protective conductor (cpc). A protective conductor connecting exposed-conductive-parts of equipment to the main earthing terminal."

"Earthing conductor. A protective conductor connecting the main earthing terminal of an installation to an earth electrode or to other means of earthing."

I'm refering to 'Bonding conductor', as in the definition above.

In your scenario if PME conditions apply, you would need to install at least a 10mm

 

[PC Electrics]

Spin is quite correct. I don't do any industrial stuff so had forgotten about this aspect. However, my "mentor" runs a 40 strong contracting company near Cannock and they do loads. When I had a similar conversation with him about it, he told me they pretty much always run a g/y alongside the swa to provide for earthing and bonding. In his cases, this is usually much cheaper than an extra core because of the larger sizes involved.

One can't help wondering why the cable manufacturers don't make any swa with a smaller g/y core a la t&e?

 

[ianmacd]

Too much hassle and they dont need to as we will always buy the 3c with the same size anyway.

Spin is quite correct. I don't do any industrial stuff so had forgotten about this aspect. However, my "mentor" runs a 40 strong contracting company near Cannock and they do loads. When I had a similar conversation with him about it, he told me they pretty much always run a g/y alongside the swa to provide for earthing and bonding. In his cases, this is usually much cheaper than an extra core because of the larger sizes involved.One can't help wondering why the cable manufacturers don't make any swa with a smaller g/y core a la t&e?

 

[ElectekAir]

In South Africa where i come from in a SWA cable there is about 10 copper strands with the steel wire Armour these are taken past the inside of the gland.

Why cant we have this here? ?:|

 

[Evans Electric]

Too simple for Britain, Electekair