Replacing 100A RCB on Heatwise System

[wormcharmer]

Replacing 100A RCB on Heatwise Switching System.
Hi everyone. I am new to the forum.

I have a 22 year old system which a relatively new economy 10 meter linked to a Heatwise switch / contactor which allows off peak electricity charging for hot water / electric boiler etc.

We get 10 hours of off peak supply which is switched via the meter and the Heatwise unit.
The Heatwise part of the system has a Hager 100A RCB rated 400V ~ 50 Hz.

When doing some minor work my electrician noticed some burn marks on the negative terminal of the RCB. The electrician was reluctant to offer a solution as the CU is the older plastic type and is over 20 years old and there maybe an issue with parts.

I have purchased an identical 100A Hager RCB ( new old stock) to replace the old one.
My initial plan today was to replace it myself, assuming the procedure was straightforward and safe.

The problem I have is that I cannot see how to isolate the supply to change the RCB. The normal top part of the consumer unit is obvious as there is an isolation switch but the section below which handles the higher load is unfamiliar to me.

I attach some pictures showing what I have.

Can anyone help with this please.

Regards

 

[Vortigern]

being an off peak supply it will be de-energised during the day presumably. However you would need to do proper testing to ensure it is dead of course before proceeding.

 

[loz2754]

There is a main switch below and to the right of the meter, cream coloured, which will isolate ALL supplies to the consumer unit. I would suggest you turn this off, rather than relying on the off peak being dead at the time.

 

[wormcharmer]

being an off peak supply it will be de-energised during the day presumably. However you would need to do proper testing to ensure it is dead of course before proceeding.

Thanks Vortigern for your suggestion. I would prefer to isolate is at all possible.

 

[wormcharmer]

There is a main switch below and to the right of the meter, cream coloured, which will isolate ALL supplies to the consumer unit. I would suggest you turn this off, rather than relying on the off peak being dead at the time.

Many thanks loz2754 I have taken the cover (1 screw) off the Heatwise box and see there is indeed a switch, see attached. OK ? I will try the switch tomorrow and check all power is off before proceeding. Many thanks for your help.

 

[Grant1987]

Many thanks loz2754 I have taken the cover (1 screw) off the Heatwise box and see there is indeed a switch, see attached. OK ? I will try the switch tomorrow and check all power is off before proceeding. Many thanks for your help.

Please don’t try changing this yourself call an electrician in do you have the testing equipment to check if it’s safely isolated? Just because one electrician wasn’t keen on touching it then doesn’t mean another more competent one won’t change it for you.

 

[Grant1987]

Please don’t try changing this yourself call an electrician in do you have the testing equipment to check if it’s safely isolated? Just because one electrician wasn’t keen on touching it then doesn’t mean another more competent one won’t change it for you.

I’ve just looked at photos this is a 3 phase supply do not touch it unless competent to do so.

 

[Grant1987]

I’ve just looked at photos this is a 3 phase supply do not touch it unless competent to do so.

Infact just looked again there is no isolation provided DO NOT TOUCH!!!

 

[pc1966]

Also is that a fuse on one of the neutrals to the right of the switch?

It might be an isolation link, but it looks an awful lot like a rewireable fuse to me!

 

[wormcharmer]

Please don’t try changing this yourself call an electrician in do you have the testing equipment to check if it’s safely isolated? Just because one electrician wasn’t keen on touching it then doesn’t mean another more competent one won’t change it for you.

Hi Grant1987, I should have perhaps mentioned that I do have the correct testing equipment to ensure the circuits are dead before proceeding plus tools, including a good screwdriver to ensure that the connections are tight.
After checking the circuits were live with multimeter (and meter worked) I isolated the supply as via the heatwise switch and the checked the consumer unit was completely dead before proceeding.
I replaced the switch, carefully tightened the connections and turned all circuits back on.
I will keep an eye on the switch but hopefully it should be good for a long time.

Thanks for everyone's help with this.

 

[wormcharmer]

Also is that a fuse on one of the neutrals to the right of the switch?

It might be an isolation link, but it looks an awful lot like a rewireable fuse to me!

Thanks for your reply. Yes it does. I haven't touched this in doing the work.