Circuit Design - HMO refurb

[LukeL81]

Hi

Pretty new here, so not sure if this question goes into this thread

I am not an electrician; however, I plan to integrate IOT devices and smart energy meters into the electricals of a house of multiple occupancies.

The house will have six bedrooms, 2 on the ground floor and 4 on the first floor.

There will be three bathrooms on the ground floor, two en-suite and one shared

There will be two more bathrooms on the first floor, one en-suite and one shared

The ground floor will also have the kitchen/living area with all the usual appliances(2 x washing machines, 2 x electric cookers, 2 x fridges, 2 x extractors)

The idea is to install 1 circuit in the CU for each room, as the total energy consumption for each room will need to be calculated by being connected to a Smart 4-channel DIN rail relay switch that will save the data remotely for further calculation.

Also, the appliance circuits will need to be connected to the Smart 4-channel DIN rail relay switch for energy consumption.

The Smart 4-channel DIN rail relay switch has

• Over Power/Current Protection
• Over Voltage Protection

So I assume we will still need an RCBO to ensure short circuits protection.

Here is what I am planning to use

Shelly Pro 4PM | Shelly Store UK | Smart Home Automation

Purchase Shelly Pro 4PM from the only Shelly authorised reseller in the UK. Shop Wi-Fi smart home automation now!

shellystore.co.uk

Based on some investigation, I think that the RCBO would be the best in terms of future proof and scalability(independently of cost); however, based on the number of potential individual circuits(at least 15 in my calculations), should this be split into 2 CUs(ground and first floor) to make sure there is enough space to install all the RCBO, SPD, etc. and the Smart relay switch(need 5 of them and each of them is the equivalent of 2 RCBOs in horizontal size).

Again, whilst I am starting to be more interested in the subject of electrical installation, I am a total noob, and a certified professional will carry the above job; however, I would like to understand if, in principle, my thought process is "correct" or it's entirely off the track to identify if I am starting to understand the concept correctly and being able to better understand the certified electrician's "language" before the works begin.

If this is not the correct forum and I should post this somewhere else, let me know

I am sure there will be many other questions, so do not hesitate to ask.

Thank you in advance for your help

 

[timhoward]

I am not an electrician; however, I plan to integrate IOT devices and smart energy meters into the electricals of a house of multiple occupancies.

Based on some investigation, I think that the RCBO would be the best in terms of future proof and scalability(independently of cost); however, based on the number of potential individual circuits(at least 15 in my calculations), should this be split into 2 CUs(ground and first floor) to make sure there is enough space to install all the RCBO, SPD, etc. and the Smart relay switch(need 5 of them and each of them is the equivalent of 2 RCBOs in horizontal size).

A HMO will unfortunately need Arc Fault Detection Devices (AFDDs) to protect all socket circuits.
Splitting the install into one circuit per room therefore has not insignificant cost implications.

 

[LukeL81]

A HMO will unfortunately need Arc Fault Detection Devices (AFDDs) to protect all socket circuits.
Splitting the install into one circuit per room therefore has not insignificant cost implications.

Thanks for the reply Tim and for the very good advice, we will need to do this anyway as it will be a requirement for us moving forward so the cost will need to be absorbed,

The need for AFDD will leave even less space for RCBOs and Smart relays so do you think my idea of having one CU for each floor is feasible?

Thanks in advance

 

[davesparks]

Thanks for the reply Tim and for the very good advice, we will need to do this anyway as it will be a requirement for us moving forward so the cost will need to be absorbed,

The need for AFDD will leave even less space for RCBOs and Smart relays so do you think my idea of having one CU for each floor is feasible?

Thanks in advance

For consumer units AFDD protection is uslaly combined with the RCBO in a single module, so there is no additional space required.

It is up to your electrician how they approach this but personally I would probably use a double row CU enclosure. Use one row for the CU and use the other row for all this smart stuff.

What exactly are you hoping to achieve by adding smart relays to all of these circuits?
If you intend to use the electricity usage data for billing the tenants then you should be aware that legally any meter used for this must meet the MID standards for accuracy, those smart relays don't make any mention of this.

 

[pc1966]

As above, you get single-module AFDD that also provide RCBO functionally.

I was going to mention MID for billing but @davesparks beat me to it!

If it is simply for general management and "no one taking the pi55" sort of checks on energy use then the Shelly units are fine.

Otherwise look at the likes of the Rayleigh Instruments range of MID certified meters that have MODBUS interfaces to allow remote reading. That is a lot more effort to use as it needs suitable RS485 interfaces and obviously the issues of ensuring that remains safely isolated from any computer, etc, has to be considered.

 

[pc1966]

Just to add, if you want both aspects you could have a MID certified meter (or channel of a multi-channel meter) for each room's billing purposes, and "within the room" (feeds to related circuits) have a Shelly device so the occupant can see how that bill is divided between lights, sockets, and electric shower use, etc.

 

[pc1966]

For billing you might not need remote access, just taking a reading (photo, etc) when they come and go would do, and then the "smart" site can use the wifi or whatever means so you avoid electrical isolation issues. Note that CU for domestic use will be metal for fire risk reduction so you might need to consider how to get an acceptable wifi or similar connection.

 

[Rockingit]

TBH - given that the majority energy use in this scenario is completely outside the bedrooms that you're wanting to meter, I'm left wondering if it's even worth it for the few watts of a TV and phone charger.... standing rate of £1 /day sounds like you'd be comfortaby in profit without any additional hassles.

 

[LukeL81]

Hey @pc1966 @davesparks @Rockingit

Thank you for your responses; already some invaluable feedback there.

To respond to your query about the actual reason behind the smart relays for energy metering is mostly, as pc1966 is saying, to monitor any unusual energy consumption activity unofficially.

Let's say we already provide radiators for heating. Still, somebody decides to plug in an electric heater, which would show a significant spike in electricity usage(independent of whether the energy meter device is certified or not) and could automatically notify the property manager.

We would also use the data for carbon footprint calculations(non-official).

The data these smart devices provide can give us an understanding of where there might be opportunities for energy savings or large overutilization from a tenant perspective and act(by talking to the tenant or implementing some automation) accordingly.

@pc1966 based on the cost increase by using FADD devices per circuit, I am thinking of just taking the approach of installing the shelly PM pro devices in each of the room's sockets and light switch; that would give me a more granular consumption per room and more flexibility in terms of automation, of course, I would need to deal with the load on WIFI channel from all the IOT devices, but that is something I have done in the past and can sort out.

@Rockingit Thank you for the suggestions, it is not just a matter of cost, but also data acquisition for multiple other requirements, hence the cost of the installation(or the effort to maintain) is not the main problem here(of course, if it would be thousands of pounds difference would be another matter)

Thank you all for your responses again, and if you have any further suggestions or questions, let me know.

Best