Sanity check on plan for CU replacement (MCB to RCBO AFDD)

[j0hnnn]

I'm planning a replacement for my existing domestic CU and would like to have it sanity checked before I get an electrician involved. The main reason for replacing the whole CU is that I would like to have an additional circuit to the attic which would be isolated from the existing one. Long story short, I've got a server rack up there which is increasing in power consumption and had a trip when a computer on the same circuit got powered on. Second reason is that the current CU is using MCBs and also there is no more space left. Instead of planning for another smaller CU, I want to get this done properly and modernised.

Existing Setup

The existing CU is 14-way (all used up). The main fuse from the supplier is 60A.

• CPN IS2100 Isolater Switch (100A) - 100A, 2 Pole. | CPN Cudis - https://cudis.co.uk/product/100a-2-pole/
• 3x CPN MC110B MCB (10A) - 10A - B Curve | CPN Cudis - https://cudis.co.uk/product/10a-b-curve/
• 3x CPN MC116B MCB (16A) - 16A - B Curve | CPN Cudis - https://cudis.co.uk/product/16a-b-curve/
• 4x CPN MC132B MCB (32A) - 32A - B Curve | CPN Cudis - https://cudis.co.uk/product/32a-b-curve/
• 1x CPN RC263/030 RCD (63A) - 63A 30mA Type B | CPN Cudis - https://cudis.co.uk/product/63a-30ma-type-b/

Upgrade Plan

I have spent the last few weeks researching everything electrical related to CUs and tried to incorporate as much of the recommendations I have read online. Since I'm not an electrician, the following is likely to not make sense, completely wrong or "overkill", hence me seeking advice. I fully understand that this plan may require rewiring and won't be cheap so money isn't going to be the significant deciding factor here.

Having looked into the different brands, I'm have made the decision to go with Hager. As mentioned previously, my immediate requirement is to have a new circuit to the attic but would be looking to have an EV charging point installed in the future. So my thought is to get the main supplier fuse upgraded. If I'm reading correctly, going form 60A to 80A could be simple but going to 100A would require a service head replacement. Also, if the cabling into the home isn't adequate, there will be extra work involved. Ideally, I get the main supplier fuse upgraded from 60A to 100A giving me more flexibility for the future. I want to get an isolation switch installed at the same time as there currently isn't one between meter and the CU. I guess I just need to get in touch with my DNO to see what they can do and whether the tails need upgrading too.

For the new CU, I'm considering the following:

• Hager VM120K CU Enclosure (20-way) - VM120K | Hager UK - https://hager.com/uk/products/h/vm120k-conunitd3020w100asw-discknockouts
• Hager VME02SPD SPD Type 2 - VME02SPD | Hager UK - https://hager.com/uk/products/h/vme02spd-cu-surge-protection-kit-type-2
• Various RCBO AFDDs:
  • Hager ARR910U (10A) - ARR910U | Hager UK - https://hager.com/uk/products/h/arr910u-rcbo-with-arc-detect1m-10a-b-6ka-a-30ma
  • Hager ARR916U (16A) - ARR916U | Hager UK - https://hager.com/uk/products/h/arr916u-rcbo-with-arc-detect1m-16a-b-6ka-a-30ma
  • Hager ARR932U (32A) - ARR932U | Hager UK - https://hager.com/uk/products/h/arr932u-rcbo-with-arc-detect1m-32a-b-6ka-a-30ma

With this in place, I'm hoping to have a second circuit installed in the attic purely for the server rack. Currently it's powered using a single socket to a 13A PDU. Maybe I can separate the load here across two PDUs plugged into two different 13A fused sockets from the new circuit, at least I should have more options. I've looked into commando sockets but like I said, unlikely I'll have a load that would warrant it.

So, how does this all sound?

 

[MJPD29]

The price of this to buy without labour is going to be eye watering. There is currently no requirement to have afdd protection for circuits in your house, it is only a recommendation for socket circuits, but not mandatory.

 

[nicebutdim]

There's nothing obvious that stands out as being problematic in your plan, but it might be best to put it to an electrician who would be able to advise on your plan in relation to specifics of the installation.

I'm sure you have good reasons for choice of circuit protection, but they aren't obvious to me and, again, something which should be discussed with whoever will carry out the work.

 

[SJD]

Re the enclosure, Hager units typically come with the option of round or rectangular knockouts top & bottom, check which would be more convenient, the part numbers are slightly different (e.g. K vs RK) to select which option.

Typically you'd buy the enclosure with the SPD already fitted, which would be cheaper than buying them separately. Again, gets specified in the part number (e.g. with an SPD suffix).

I installed a consumer unit with a selection of Hager AFDDs recently (care home). The AFDDs were quite expensive, circa £100 each. As just mentioned, it is only a recommendation (assuming you are not a care home), and unless money really is no object, I'd consider if you really need them all. The Hager AFDDs can be connected to from a phone/laptop etc via Bluetooth, and you can download the last 16 (I think) trips, with data like what type of trip, how long the circuit was up. But I found the software a bit clunky and immature to use and did not work quite as described, though I did manage to connect and see this data. You can upload new firmware to the AFDDs if needed.

That said, the reason I chose Hager over my usual brand (Fusebox) is the expectation that Hager would more likely to still be around in 10 or 20 years for spares.

 

[j0hnnn]

The price of this to buy without labour is going to be eye watering. There is currently no requirement to have afdd protection for circuits in your house, it is only a recommendation for socket circuits, but not mandatory.

Yea, it's not going to be cheap. If I do all the breakers (11) as the AFDD type, it comes to around £1100 just for those. As an alternative, I could just do the lights circuits on their standard RCBOs (ADA310G | Hager UK - https://hager.com/uk/products/h/ada310g-rcbo-1p-6ka-b-10a-30ma-type-a-1m) and rest AFDD variant.

I'm sure you have good reasons for choice of circuit protection, but they aren't obvious to me

Just thinking that if money wasn't a significant factor, am I better off just following recommendations albeit not being mandatory - yet?

Re the enclosure, Hager units typically come with the option of round or rectangular knockouts top & bottom, check which would be more convenient, the part numbers are slightly different (e.g. K vs RK) to select which option.

Thanks, I was actually trying to figure out the difference between VM120 and VM120K, this cleared it up (hopefully the electrician would know about this).

Typically you'd buy the enclosure with the SPD already fitted, which would be cheaper than buying them separately. Again, gets specified in the part number (e.g. with an SPD suffix).

I saw a few with SPD options but wasn't sure if the SPD provided is the same type or lower quality. I initially looked at Type 1 + 2 SPD but this wasn't available in the SPD suffixed part numbers so ended up with Type 2. I should probably consider the ones with SPD fitted if it's the same one they are selling individually.

As just mentioned, it is only a recommendation (assuming you are not a care home), and unless money really is no object, I'd consider if you really need them all. The Hager AFDDs can be connected to from a phone/laptop etc via Bluetooth

I most likely don't need them all to be AFDD, considering now as per pervious message just to do sockets and anything high current to use them instead. I saw the Bluetooth connectivity and the app and did read about some hoops you have to jump through during FW upgrades but alas, it's a nice to have and wouldn't have much bearing on the decision making.

 

[nicebutdim]

Yea, it's not going to be cheap. If I do all the breakers (11) as the AFDD type, it comes to around £1100 just for those. As an alternative, I could just do the lights circuits on their standard RCBOs (ADA310G | Hager UK - https://hager.com/uk/products/h/ada310g-rcbo-1p-6ka-b-10a-30ma-type-a-1m) and rest AFDD variant.


Just thinking that if money wasn't a significant factor, am I better off just following recommendations albeit not being mandatory - yet?

There's no reason not to fit AFDDs, but is there any benefit in doing so? Is the property used for commercial purposes?

I saw a few with SPD options but wasn't sure if the SPD provided is the same type or lower quality. I initially looked at Type 1 + 2 SPD but this wasn't available in the SPD suffixed part numbers so ended up with Type 2. I should probably consider the ones with SPD fitted if it's the same one they are selling individually.

What is the earthing arrangement at the property? Buying what you think is best might be an ultimately pointless exercise. This ties in with my suggestion to engage the services of an electrician, rather than compile a shopping list on the basis of information gathered from various parts of the internet. Regardless of how good a source might be, they won't reimburse you for items bought that don't meet the requirements of your installation.

 

[davesparks]

It is good that you have read up on this and familiarised yourself with the options, but I'd suggest you don't fix on a particular manufacturer or specific arrangement until you've spoken to the electricians who will be quoting the job.

We all work slightly differently and have our preferred manufacturers so get a few quotes from a few electricians and see what they say.

As far as AFDDs go you have obviously researched them and have decided you'd like to add this type of protection, so if the price is not an issue for you then go ahead with it.
Just be aware that they are a relatively new technology and any tripping problems will take a bit longer to diagnose as we just don't have the years of experience we have about other faults and tripping problems.

 

[pc1966]

I would add that if you have reason to want the AFDD added arc-fult protection then Hager are a good choice as they support bluetooth diagnostics and the ability to update firmware. I'm not sure anyone else does that.

As @davesparks says many sparkys have favourite brands so might want to offer others, but if you are looking for high quality then Hager and Schneider are your best bets if affordable.

 

[nicebutdim]

I would add that if you have reason to want the AFDD added arc-fult protection then Hager are a good choice as they support bluetooth diagnostics and the ability to update firmware. I'm not sure anyone else does that.

As @davesparks says many sparkys have favourite brands so might want to offer others, but if you are looking for high quality then Hager and Schneider are your best bets if affordable.

If this premises is domestic I'd add Crabtree starbreaker to the list, for ease of future additions. Although no Bluetooth connectivity would be possible.

 

[pc1966]

If this premises is domestic I'd add Crabtree starbreaker to the list, for ease of future additions. Although no Bluetooth connectivity would be possible.

The Crabtree Starbreaker are nice, innards same as Wylex, and one of the original single-module AFDD. As for the RCBO they have the nice feature of neutral-switching.