Tns or tncs ?

Hi all, 

just moved into new (old) house and have been investigating the current installation. Couple of things concern me including no bonding to gas or water, open choc block connections buried in insulation which are joining what appears to be different size cables and colours etc. 

I will I'll be getting quotes for a rewire next month when funds allow including wiring to new garage. In reading up about bonding I got to reading about earthing systems etc. Can anyone tell from the following pics if it is tns or tncs ? The old metal cable has been cut and replaced. Earth wire drops out bottom of cutout wrapped in insulation. Most pics I see online of tncs the earth wire comes out the side rather than the bottom and is usually insulated cable.

I am in Scotland if that makes any difference. 

Looks like TN-S, but a call to your supplier should verify that.

Thanks lurch,

Will I need this info for the spark when he comes or will he know anyway ?

i suppose if I phone the supplier I can ask them to upgrade the 60a fuse if there is capacity to do so. Main cable is approx 18mm outer diameter ? House used to be a 2 bed bungalow but has had a basement conversion to make it 4 bed with 2 family rooms. Hob and double oven currently on separate 32a supplies, both rated at 7250kw each,  I also want the guy to put in a supply to the new garage to feed 2x 16a supplies for compressor and welder, ring main and lighting for about 6 fluorescents so guessing that the 60a might be pushing it on a Sunday afternoon with the roast dinner on while I'm welding and the compressor happens to kick in ?

Pippo said:

Will I need this info for the spark when he comes or will he know anyway ?

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No, he should know and be able to advise further. Same with the bonding arrangements and wotnot, nothing wrong with you picking up a few basics but ultimately he should be able advise the best overall solution.

Pippo said:

i suppose if I phone the supplier I can ask them to upgrade the 60a fuse if there is capacity to do so.

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The cable might be new and capable, it's the rest of the supply/network that could be limited. You can ask, they might give a sensible answer. If you do want it upgrading there will be a form to fill in and send off though. Again, your electrician should be able to help with this. I wouldn't worry too much though if you can't, 60A isn't as limiting as it sounds, and the ovens aren't going to both be on full chat all afternoon, same with the welder/compressor. Once diversity is applied as well the 60A supply will be well within spec.

Thanks for the advice lurch.

pippo

From the shot of the cable crotch it’s a split concentric so more than likely TN-S.

There’s an old 7/.044 2c PILC chopped of just near the new service, I wonder what happened to that?

most likely TNS. either call DNO or it could be tested to see if its TNS or TNCS

The thing is Andy, if TN-C-S is presented as TN-S at the consumers installation, then no matter what the readings, it's TN-S.

Hi there. I would not be too worried ablout having a 60A fuse. They take an awful lot of blowing. I used a 330A single phase welder on 230v here for years and it never blew the fuse once..

john..

Cheers all, glad to know the 60a will likely be up to the job. It's only a 180a inverter mig welder I have.

As for the old cable that's been cut, it's buried in the old lime plaster so probably decided to cut and leave it in. I assume it's the original incoming cable when the house was built in the 30s. Appears to be made of lead or similar

Yes it will be paper lead insulated cable Pippo, an probably correct in assuming it has been chopped out (albeit not very flush) to avoid damaging the plaster.