Cable Size

John.G

I have a 51 year old house and recently got a smart meter installed, the electrician also installed a new isolating switch, you can see the (original) wires going to the fuse board. I get a OD of 4.6/4.75MM when I measure these wires with a vernier calipers which might indicate only 6mm2 wiring??, I dont know if these wires are single or multi strand. The fuse holder is marked 60A/80A, I think it has a 60A fuse, so assume I have a 12KVA supply. Is this normal?, cable size, etc.

Another query, what is the purpose of the three tie wraps on the wires?

Isolator.jpg

kirk.

The tie wraps are cable identifiers for line and neutral .Smart meter installers fit them

The wiring looks odd but hard to tell from that picture

kirk.

Doesn't seem right L N N on the smart meter ? , maybe I'm missing something obvious

John.G

Underneath, you have L1 and IN, presume the third wire is the earth and isn't switched, Is the isolator a DP and switches out the live and the Neutral?.

Its the wiring size that seems quite small? at ~ 4.7mm diameter.

Isolator from Afar.jpg

Isolator Underneath.jpg

4.7mm.

kirk.

That's an isolator not a smart meter , my bad

Cable colors are odd looks like a brown neutral and yellow earth , seem to be about 6 sq

A basic supply is 12 kva but thats mostly dependent on the supply quality , lines, service cable and transformers

Size of cabling at cabinet isn't that important if everything else is in order

kirk.

Last time I checked my isolator was single pole

The isolator at the cabinet isn't a consumer device .It's just an interface and a means for REC to switch off

DP isolation is at the distribution boards. Switches both live conducters for domestic work

Lenar3556

The wiring does look small John - likely 6mm2. To put that in perspective 16mm2 would be the minimum standard for that size supply in a new installation.

I don’t know what kind of loads you have in your house, but the practical issues are that is could be be overloaded at certain times depending on what you have switched on.

It is also not very well protected in terms of overcurrent. The ESB service fuse is possibly 60A and that 6mm2 cable will limit the prospective short circuit current required to blow the fuse in a timely manner.

The isolator is single pole (breaks live only). The neutral provides the primary low impedance fault path in most installations so you wouldn’t want to interrupt it at this point.

kirk.

Put up a picture of the cabinet and metering to see is there any reverse polarity

Hard to tell much from those pictures

Just noticed the MPC (main earth ) has a blue tag , wtf is that about

Looks like a brown with a blue tag also at isolator

kirk.

https://www.boards.ie/discussion/comment/120720597#Comment_120720597

Main protective conductor connects to fused cutout so you're not breaking the fault path at the isolator by switching neutral

John.G

Photo 1.jpg

Photo 2.jpg

Here you are.

kirk.

Polarity is ok

Dunno what that blue marking on earth is about

Conducters are undersized but hard to know what's going on there

John.G

My biggest load is a 9kw shower with ~ 10m (20M to and from) of 6mm2 from the RCBO to the shower, the shower is used in the morning so little or no other continuous loads, shower only on for a max of 10 minutes and mostly < 5 minutes. I measured the temperature rise in the L&N from the isolator and it went from 27C to 29C after 5 minutes, 29C to 33C after another 5 minutes and 29C to 36C after another 5 minutes (15 minutes in all). By my calculations, the power lost in the 20M of wiring is ~ 92W or 4.6W/meter so maybe 9.2W/meter emitted with the wires side by side in the cable?.

kirk.

You'd need more photos main board and cabinet if there's a concern