"disconnected" old immersion heater point gives a reading on fluke tester

[jonboy2015]

A relative has asked me to install an electric shower. He suggested i use an old electrical point that used to be used for an immersion heater, but has now been plated off with a blank plate and the live and neutral wire inside have been taped off with red insulation tape.

I used my fluke clamp meter to check if the old wires of this old immersion heater point are still live and i get a 0.1 V ac readings when the clamp is used around the wires. To check things further i checked his consumer unit which is a wylex unit with his properties circuits split into 2 x socket RCD's on one side and a lighting RCD and a Cooker RCD on the other side.

Now, i'm trying to distinguish where this old immersion heater wiring is being supplied from and would it even be sufficient for the new 8.5 Kw Mira shower. I knocked off each RCD individually while testing the reading of the old wiring and each time it still shows 0.1 V ac regardless but when i knocked off the main 100A isolator the reading shows a 0.0 V ac reading. Can anyone help as to where this wiring could be possibly getting its supply from and is it sufficient wiring anyway? or should i simply run a new 10mm from a 45 A RCD at the consumer unit to supply his new Mira shower instead? Any help would be greatly appreciated folks!

 

[Marvo]

Are you a sparky?

The 0.1v is a meaningless reading. Did the circuit test at 230v when all the circuits were energised?

 

[TJ Anderson]

A relative has asked me to install an electric shower. He suggested i use an old electrical point that used to be used for an immersion heater, but has now been plated off with a blank plate and the live and neutral wire inside have been taped off with red insulation tape.

I used my fluke clamp meter to check if the old wires of this old immersion heater point are still live and i get a 0.1 V ac readings when the clamp is used around the wires. To check things further i checked his consumer unit which is a wylex unit with his properties circuits split into 2 x socket RCD's on one side and a lighting RCD and a Cooker RCD on the other side.

Now, i'm trying to distinguish where this old immersion heater wiring is being supplied from and would it even be sufficient for the new 8.5 Kw Mira shower. I knocked off each RCD individually while testing the reading of the old wiring and each time it still shows 0.1 V ac regardless but when i knocked off the main 100A isolator the reading shows a 0.0 V ac reading. Can anyone help as to where this wiring could be possibly getting its supply from and is it sufficient wiring anyway? or should i simply run a new 10mm from a 45 A RCD at the consumer unit to supply his new Mira shower instead? Any help would be greatly appreciated folks!

The 0.1V is induced from another circuit and negligible (disregard it). The Immersion will most likely be 2.5mm so not suitable for electric shower (unless you are having a hand wash as a shower )

 

[Octopus]

This should be in the DIY section, before the vultures swoop!

 

[Des 56]

Perhaps your uncle should think about a shower off the combi

 

[TJ Anderson]

Perhaps your uncle should think about a shower off the combi

I like it and also how you came to that conclusion on the combi. (I thought the same ). The Uncle..... you must have inside info lol

 

[snowhead]

It's Friday the 13th,, right?

 

[telectrix]

A relative has asked me to install an electric shower. He suggested i use an old electrical point that used to be used for an immersion heater, but has now been plated off with a blank plate and the live and neutral wire inside have been taped off with red insulation tape.

I used my fluke clamp meter to check if the old wires of this old immersion heater point are still live and i get a 0.1 V ac readings when the clamp is used around the wires. To check things further i checked his consumer unit which is a wylex unit with his properties circuits split into 2 x socket RCD's on one side and a lighting RCD and a Cooker RCD on the other side.

Now, i'm trying to distinguish where this old immersion heater wiring is being supplied from and would it even be sufficient for the new 8.5 Kw Mira shower. I knocked off each RCD individually while testing the reading of the old wiring and each time it still shows 0.1 V ac regardless but when i knocked off the main 100A isolator the reading shows a 0.0 V ac reading. Can anyone help as to where this wiring could be possibly getting its supply from and is it sufficient wiring anyway? or should i simply run a new 10mm from a 45 A RCD at the consumer unit to supply his new Mira shower instead? Any help would be greatly appreciated folks!

if you think an old immersion heater feed is adequate for a 8.5kW shower, then i'm afraid you're out of your comfort zone here. thew shower will require a 6mm dedicated radial. if you can't work it out, give me a call.

 

[cotty]

It's Friday the 13th,, right?

 

[telectrix]

like the self portait, cotty.

 

[cotty]

like the self portait, cotty.

I must admit, it's one of my best!

 

[jonboy2015]

if you think an old immersion heater feed is adequate for a 8.5kW shower, then i'm afraid you're out of your comfort zone here. thew shower will require a 6mm dedicated radial. if you can't work it out, give me a call.

Many thanks mate, and folks ...including psychic Des56 , for your info and replies, i have wired showers before as a trainee electrician and have used 6mm and when looking at the wiring of this old immersion heater the wiring looked much thicker than the normal 2.5mm t&e and more like that of 6mm so i thought if this was still usable then it may save me running new cable. So it looks like i need to run 6mm from the consumer unit. Just another couple of questions, can i run from CU to a wall mounted switch in a nearby cupboard rather than a pull cord? as i'm dealing with concrete ceilings here. Also i guess a 40A mcb is sufficient with using the 6mm run? Cheers folks

 

[Marvo]

This is turning into requesting step by step instructions which means I'm going to close this thread.

Cable size required depends on the load, the length of cable and the installation method. Every installation is different, you need to refer to the tables in the regs books to work this out. Switch location is also governed by the bathroom zones so agani you'll need to refer to the regs book.