When to use your own earth rods

[cojmh]

16mm2 earth conductor is sufficiently robust that it didn’t need mechanical protection so can be direct buried, clipped etc

Thank you

[Stinsy]

• You should have the RCDs in your house tested, they're probably fine though, the same ones are used for TN and TT systems. Worths swapping any "split" boards for all-RCBO while you're messing about though. However important point is that you'll need an additional "type s" RCD. You can swap out the main switch on your CU(s) for one of these. (Hope this makes sense)

So I have been doing quite a bit of digging on this and I am beginning to understand what I might need .... but a couple of things are still confusing me.

1. There are various types of RCBO and I think it is type B that I want as more and more devices use inverter drives etc. and this is why type A is not necessarily the best fit for the job (according to a youtube video from what seemed like a knowledgeable person). However I keep finding Type B RCBO's that then say they are Type A RCBOs with a type B curve and I have to admit this has somewhat confused the matter for me. Can you have a type A RCBO with a type B curve and is this different from a type B RCBO?

2. I don't understand the "type S" RCD .... I can only seem to find info on Type AC, A, F, B and B+ ..... so could you explain a little more what the type S is as I might be looking for the wrong thing? I also am not sure why this is necessary as my (rather basic) understanding is that each RCBO effectively has and RCD in it .... so why is an additional one needed?

Thanks for any help and I apologise if I am completely missing the point.

1. The naming conventions are really dumb! There are “types”. Up until very recently type AC were the most common, however they have a whole load of weaknesses. Primarily “dc blinding”. If you have a large DC load such as a SMPS in LED bulbs, laptop chargers, TVs, etc., the RCD won’t work. This is especially problematic with “split” boards where one RCD covers several circuits. So a granny cable charging an EV will prevent the RCD from detecting a fault on your washing machine and the Mrs gets killed. For this reason type-AC RCDs have been banned for maybe years in some European countries, but we’ve only very recently been installing better RCDs. Type A is now the standard and you’ll find it very easy to find type A RCDs and RCBOs. Type B and Type F RCDs provide additional levels of protection, but they’re quite new and you might struggle to find RCBOs thus rated and have to use RCCBs together with MCBs instead.

Then you have “curves”. This isn’t to do with the RCD protection, it is about overcurrent protection. These come in B, C, D, K, and Z. I could go on about these in detail, but the only relevant part is that you’ll need a B curve. Just be sure not to confuse b curve with type b (marketing folk and the people writing listings on e-commerce websites do you no favours by getting this wrong themselves).

2. TT installations are required to have a type S 100mA time-delay RCD in addition. This is a backup in case the other RCD fails. Usually you have one covering the whole installation. The idea is to provide “selectivity” so that the type S only trips if the main RCD has failed.

[AGT]

You only need an earth rod if your system operates in island mode ie during. Power failure

[AGT]

[chris_n]

The reasons this is not a good idea has already been discussed in this thread.
https://camelot-forum.co.uk/phpBB3/view ... =20#p51212

[AGT]

Well that’s the IET EESS Code of Practice that’s the photos came from….
If it all went Pete Tong, I will be following that

[cojmh]

Well that’s the IET EESS Code of Practice that’s the photos came from….
If it all went Pete Tong, I will be following that

Thanks for the info.

I think the reason for switching to fully TT was that I wanted to run power from the house to an outbuilding and from what was discussed previously in this thread ... that was (and possibly still is) a no no.

There was also the valid point that you would have to have some trust in the switch over contactor working properly. I personally don't have any experience of this but those that have more experience/knowledge than me have highlighted the issue for consideration.

Given all of this and the relative ease with which I can install two, hopefully, quite deep earth rods means that I am seriously considering just going to a TT connection and then I don't have to worry about anything unless a cable is cut somewhere! Plus I will just add regular checks on the earth rods to things that need to be done on the house.

Hopefully this makes logical sense.

I am currently trying to figure out what needs to be done at the consumer unit end as I think it is wise to switch over to RCBOs .... whilst I am doing all this work.

At the moment I think the following is what I will get getting done.


Main Consumer Unit

• PV - 32A

• Eddi - 16A

• Outbuilding - 40A

• Zappi Charger - 32A - This is a future install but I need to maintain the spot

• AC 1 - 16A - This is a next year install

• AC 2 - 16A - This is an install probably 2-3 years down the line

• Shower 1 - 40A - This will be removed next year and I am pretty sure the shower is about 5KW

• Shower 2 - 40A - This will be removed in a couple of years and I am pretty sure the shower is about 5KW

• Kitchen/Cooker - 40A

Switchable Consumer Unit

• Exterior lighting - 6A

• Ring Main Downstairs -32A

• Ring Main Upstairs -32A

• Ring Main Lofts - 32A

• Lighting Downstairs - 6A

• Lighting Upstairs - 6A

• Outbuilding- 16A - This is mainly to provide lights and CCTV in a power cut

• Solar Thermal - 6A - To be added next year

• Front External Plug 16A

I think I will switch all of the to RCBOs (Type A, Curve B) to ensure everything is the same and will also replace the main switch in the consumer unit to a Type S RCD

[AGT]

Not seen any 5kW electric showers?
Lots of power getting used, shower priority switch?
Any hybrid inverter in the future?

[AGT]

What’s the outbuilding constructed from?

[Stinsy]

Well that’s the IET EESS Code of Practice that’s the photos came from….
If it all went Pete Tong, I will be following that

Thanks for the info.

I think the reason for switching to fully TT was that I wanted to run power from the house to an outbuilding and from what was discussed previously in this thread ... that was (and possibly still is) a no no.

There was also the valid point that you would have to have some trust in the switch over contactor working properly. I personally don't have any experience of this but those that have more experience/knowledge than me have highlighted the issue for consideration.

Given all of this and the relative ease with which I can install two, hopefully, quite deep earth rods means that I am seriously considering just going to a TT connection and then I don't have to worry about anything unless a cable is cut somewhere! Plus I will just add regular checks on the earth rods to things that need to be done on the house.

Hopefully this makes logical sense.

I am currently trying to figure out what needs to be done at the consumer unit end as I think it is wise to switch over to RCBOs .... whilst I am doing all this work.

At the moment I think the following is what I will get getting done.


Main Consumer Unit

• PV - 32A

• Eddi - 16A

• Outbuilding - 40A

• Zappi Charger - 32A - This is a future install but I need to maintain the spot

• AC 1 - 16A - This is a next year install

• AC 2 - 16A - This is an install probably 2-3 years down the line

• Shower 1 - 40A - This will be removed next year and I am pretty sure the shower is about 5KW

• Shower 2 - 40A - This will be removed in a couple of years and I am pretty sure the shower is about 5KW

• Kitchen/Cooker - 40A

Switchable Consumer Unit

• Exterior lighting - 6A

• Ring Main Downstairs -32A

• Ring Main Upstairs -32A

• Ring Main Lofts - 32A

• Lighting Downstairs - 6A

• Lighting Upstairs - 6A

• Outbuilding- 16A - This is mainly to provide lights and CCTV in a power cut

• Solar Thermal - 6A - To be added next year

• Front External Plug 16A

I think I will switch all of the to RCBOs (Type A, Curve B) to ensure everything is the same and will also replace the main switch in the consumer unit to a Type S RCD

My comments:

• You need to do max-demand calculations! Very doubtful that you'd get away with 2x electric showers...

• THe circuits you're referring to are not "ring mains" they are "ring finals".

• IMO you've got way too much on the UPS/EPS CU. No need to have all your sockets powered in the event of an outage. Lights I agree with, and you'd want your wifi router, TV, and a few strategically-places sockets for phone/laptop charging, but think carefully before adding anything else.

• I wouldn't put the outbuilding on the EPS/UPS supply either. Just fit an emergency light with a self-contained battery, and use a UPS to power your CCTV via a PoE switch.

• Soalr thermal isn't worth it these days, just fit more PV.

• Convention states that you should list circuits from biggest to smallest.