SWA and Earthing

[JSSE]

I work in a production maintenance environment and have little domestic knowledge and have a question if i way about the earthing of the armouring of SWA. The question arises from my neighbours free solar install. From the invertor in the loft to the PV RCD in his garage the cable installed is 3 core SWA. The isolators fitted at either end are the MK type plastic enclosed isolators that i use at work for local isolation and lock off purposes adjcent to motors etc. Now the glands have been fitted with banjos as these can be seen and have nothing attached to them. Now i would without question always use a core as a cpc but would still earth the armourings as well. My system is being fitted in two weeks by thge same company and i would like comments from you domestic guys on this issue, reg quotes etc.

Also the test results sheets for the install lists the invertor as a sunnyboy but it is not is another type does this matter?

Many Thanks
Jon

 

[fivestar]

If not being used as a CPC (and I am with you there, I never use the amour as a CPC) the amour should normally be earthed at the supply end - otherwise it cannot peform its function of providing a low resitance path to earth in the event of the cable being cut into.

 

[telectrix]

not really relevant, but check out SWA ( the manufacturer, not cable ) Locking Earth nut - does away with need for banjos and makes a really neat job of earthing to SWA cable gland esp in plastic boxes

 

[malcolmsanford]

First thing I would ask is why have that installed with SWA? is it running outside and burried don't sound like it would be buried, is it outside running down the wall?

From the array and before the invertor should be a DC isolator. Normally you will have an AC isoltor the other side of the invertor on your AC side in the loft also. Then as in your neighbours case the SWA will connect into that AC isoltor from Feed in meter. You then may have another AC isolator at the CU.

The SWA should have banjo's and a fly earth wether the terminate in plastic or metal. As you say they have run a 3 core then I would assume the 3rd core was used as a CPC. If that is the case then the SWA should be earthed at one end only, if they have use plastic then unless you have that fly lead you have no earth.

As for the mis naming of the invertor. If it's an EIC then the name of the equipment is not normally mentioned. If as I think you also have a PV commissioning certificate then it might be relevant. But what ever it don't show a very professional attitude does it.

 

[rallyandy]

I agree with telectrix, I use the locking earth nuts with all SWA installs as they are far superior to banjos, look neater, and much quicker and easier to install, also as malcolmsanford states as long as one core is used for CPC then the armoured only needs to be terninated at the supply end, hope this helps

 

[telectrix]

and no dissimilar metal corrosion either as with steel nuts