Circuit Metering

[LED Lighting]

Hi All

I have been asked to install a New DB to serve 40 offices, with the facility to meter each office individually.
I was thinking of installing a 18way TP&N DB, running 10mm to each office where a smaller SP CU is installed branching off to 3 circuits. Lights, Sockets and electric heater. A Din Rail Energy Monitor would be installed in this CU.

Whole install is in Dado and plastic trunking on the surface so RCD is in the office CU and not the 3P&N DB.


Any thoughts on this or any other way of doing it.

 

[telectrix]

what's the earthing arrangement?

 

[LED Lighting]

what's the earthing arrangement?

pme/tnc-s

 

[Pete999]

What's the demand like?

 

[davesparks]

What type of protection were you thinking of using for the sub-mains?
You can get SP boards with meter packs these days which also have communications options so these meters could all be remotely monitored

 

[LED Lighting]

What type of protection were you thinking of using for the sub-mains?
You can get SP boards with meter packs these days which also have communications options so these meters could all be remotely monitored

Any links would be greatly appreciated.

I was thinking just MCB protection in DB and RCD in Sub SP Board.
Thinking no requirement for RCD between DB and SP Board as the supply is in trunking

 

[LED Lighting]

What's the demand like?

3KW approx per room.
Total of 30-40 offices on this DB.

Offices will have 5 double sockets (PC use), 1 x 1KW Heater and LED Lighting

 

[davesparks]

Any links would be greatly appreciated.

I was thinking just MCB protection in DB and RCD in Sub SP Board.
Thinking no requirement for RCD between DB and SP Board as the supply is in trunking

Any non-domestic board should have various meter pack options these days

So you arent interested in providing any discrimination between ocpds then?

 

[Leesparkykent]

3KW approx per room.
Total of 30-40 offices on this DB.

Offices will have 5 double sockets (PC use), 1 x 1KW Heater and LED Lighting

Edit: link didn't work

might be better to use something like these for the distribution circuits.

 

[LED Lighting]

Any non-domestic board should have various meter pack options these days

So you arent interested in providing any discrimination between ocpds then?

OCPDS?????

Sorry I not that quick with abbreviations

 

[Simonslimline]

over current protective device

 

[LED Lighting]

http://www.hager.co.uk/product-catalogue/energy-distribution/protection-devices/fuse-carriers/hrc-fuse-carriers-bs88/ls201/47120.htm

might be better to use something like these for the distribution circuits.

Whats the benefit of using these?
I was thinking MCBs are readily available and anything else the client wants to add later on they can.

 

[davesparks]

Whats the benefit of using these?
I was thinking MCBs are readily available and anything else the client wants to add later on they can.

The benefit is that you will actually be able to comply with the regulations concerning discrimination, which you won't be able to do with MCBs.

 

[LED Lighting]

Any non-domestic board should have various meter pack options these days

So you arent interested in providing any discrimination between ocpds then?

What do you mean about discrimination of over current protective devices?
There will be a 50A MCB in the DB, and in the CU there will be 32A - Sockets, 16A - Heater and 6A Lighting.
They wont even get anywhere near this.

The offices are single occupancy offices so they should not even use 20A day to day.

 

[Leesparkykent]

Whats the benefit of using these?
I was thinking MCBs are readily available and anything else the client wants to add later on they can.

would provide better discrimination. you will struggle to achieve discrimination between MCB's. For example a fault on the lighting circuit in the office could just as easily trip the MCB feeding the distribution circuit taking out the computers.

 

[LED Lighting]

The benefit is that you will actually be able to comply with the regulations concerning discrimination, which you won't be able to do with MCBs.

Can you point me to the regulation about this please. As I have not come across this one yet.

 

[LED Lighting]

would provide better discrimination. you will struggle to achieve discrimination between MCB's. For example a fault on the lighting circuit in the office could just as easily trip the MCB feeding the distribution circuit taking out the computers.

So am I right in saying, 1361 feeding DB, 1361 in DB feeding CU, and MCB/RCBO in CU??

 

[davesparks]

What do you mean about discrimination of over current protective devices?
There will be a 50A MCB in the DB, and in the CU there will be 32A - Sockets, 16A - Heater and 6A Lighting.
They wont even get anywhere near this.

The offices are single occupancy offices so they should not even use 20A day to day.

With respect, are you sure you are qualified to design an electrical installation of you don't understand the principal of discrimination of ocpds?

Look at the manufacturers data including tripping curves and times for the MCBs to see how they will discriminate

 

[Leesparkykent]

So am I right in saying, 1361 feeding DB, 1361 in DB feeding CU, and MCB/RCBO in CU??

yes or bs88.

 

[davesparks]

So am I right in saying, 1361 feeding DB, 1361 in DB feeding CU, and MCB/RCBO in CU??

BS88 fuses or correctly set MCCBs are what you need, bs1361 has been replaced/merged into bs88 now

 

[Simonslimline]

Have a gander at this. Guide to discrimination | edmundson-electrical.co.uk

 

[Leesparkykent]

536.1 page 151 BYB

 

[LED Lighting]

Edit: link didn't work

might be better to use something like these for the distribution circuits.

You suggested this one, but I am struggling to find anything bigger than a 32A.

I have found a 50A Single pole in India Hager Site but nothing on the UK Hager site.

 

[Leesparkykent]

You suggested this one, but I am struggling to find anything bigger than a 32A.

I have found a 50A Single pole in India Hager Site but nothing on the UK Hager site.

I don't think you will find a 1 module carrier over 32A. realistically do you think you need to provide 50A to each office?
you will find it easier with regards to metering with 32A distribution circuits IMO as that's what most 1module din rail mounted KWH meters are rated to. just my opinion...

 

[davesparks]

Try these
http://www.neweysonline.co.uk/mem-d...way-tpn/1050071940/ProductInformation.raction

https://www.sparksdirect.co.uk/24-w...-fuse-units-24-way-tpn-fuseboard#.VoA0ISOnxDs

 

[LED Lighting]

I don't think you will find a 1 module carrier over 32A. realistically do you think you need to provide 50A to each office?
you will find it easier with regards to metering with 32A distribution circuits IMO as that's what most 1module din rail mounted KWH meters are rated to. just my opinion...

Only concern I have is they will be running 5 Double sockets, 1 Heater (1.5KW) and a 40W LED Lamp.
I dont think the load will exceed 32A but it might get close if they have a kettle & heater on at the same time.

 

[Leesparkykent]

If you go down the route of fuse carriers like Davesparks has posted links to, also have a look at lucyelectric.

 

[LED Lighting]

Try these
Buy MEM Distribution Fuseboard, Exel, 63A, 8 Way, TPN - 608XTNC

https://www.sparksdirect.co.uk/24-w...-fuse-units-24-way-tpn-fuseboard#.VoA0ISOnxDs

Thanks but neither will be big enough, theres 40 offices, so needs to be 16 or 18 way TP&N

I was looking at the Hager or Havells 18Way DB, just need to find a suitable fuse carrier.

Does anyone have any concern about a 32A BS88 not being big enough for the demand? The calculations say it should be fine.

 

[Leesparkykent]

Only concern I have is they will be running 5 Double sockets, 1 Heater (1.5KW) and a 40W LED Lamp.
I dont think the load will exceed 32A but it might get close if they have a kettle & heater on at the same time.

how many computers per office?

 

[LED Lighting]

how many computers per office?

Theres 2 types of office.
Office 1: 1 Computer, 1 Heater (1KW) and lights. Total of 5 D Sockets
Size: 3m x 2.5m

Office 2: 2 Computers, 1 Heater (1.5KW) and lights. Total of 8 D Sockets
Size: 3m x 5m

 

[davesparks]

Thanks but neither will be big enough, theres 40 offices, so needs to be 16 or 18 way TP&N

I was looking at the Hager or Havells 18Way DB, just need to find a suitable fuse carrier.

Does anyone have any concern about a 32A BS88 not being big enough for the demand? The calculations say it should be fine.

Not big enough? The second link is a 24way TPN, that gives 72SP ways!
They were only examples of what is available out there, its up to you to specify the exact product you need.

I have many concerns about this, least of all the rating of the fuse

 

[davesparks]

Only concern I have is they will be running 5 Double sockets, 1 Heater (1.5KW) and a 40W LED Lamp.
I dont think the load will exceed 32A but it might get close if they have a kettle & heater on at the same time.

So calculate the design load of the submain and take it from there,

 

[LED Lighting]

Not big enough? The second link is a 24way TPN, that gives 72SP ways!
They were only examples of what is available out there, its up to you to specify the exact product you need.

I didnt want to go down the route of a Reyley Board because this DB will also supply lighting and Sockets to the hallways and the toilets.

 

[davesparks]

I didnt want to go down the route of a Reyley Board because this DB will also supply lighting and Sockets to the hallways and the toilets.

You are very unlikely to get a single board capable of fulfilling all your requirements here, much better to have a board for the distribution circuits and another for the final circuits.
I thought this kind of basic design was still taught as part of an apprenticeship?

 

[LED Lighting]

So calculate the design load of the submain and take it from there,

I have: 5.5KW max. but Im only unsure as I have no control of what the office users bring into the offices.
Total demand of 5.5KW is 24A.

 

[LED Lighting]

You are very unlikely to get a single board capable of fulfilling all your requirements here, much better to have a board for the distribution circuits and another for the final circuits.
I thought this kind of basic design was still taught as part of an apprenticeship?

The other problem I have is the budget. It wont facilitate a £1,000 DB Board!

 

[Leesparkykent]

Theres 2 types of office.
Office 1: 1 Computer, 1 Heater (1KW) and lights. Total of 5 D Sockets
Size: 3m x 2.5m

Office 2: 2 Computers, 1 Heater (1.5KW) and lights. Total of 8 D Sockets
Size: 3m x 5m

2x computers/monitors 600W, heater 1500W, lights led lighting 200W-300W max. Around 10.5A max... leaves plenty of room on a 32A.

 

[davesparks]

The other problem I have is the budget. It wont facilitate a £1,000 DB Board!

You're buggered then of the pricing of the job is being done backwards, you wont be able to deliver a safe amd compliant installation.
Design should be done first, then quotes submitted based on the approved design. Not the price set and then the design bodged to fit it.

 

[LED Lighting]

You're buggered then of the pricing of the job is being done backwards, you wont be able to deliver a safe amd compliant installation.
Design should be done first, then quotes submitted based on the approved design. Not the price set and then the design bodged to fit it.

No Quote has been submitted or Design.

Thanks for all your help, I agree that a 32A should be more than big enough for this project.
I was just a bit over concerned as the sockets are running off a 32A.

 

[Leesparkykent]

The other problem I have is the budget. It wont facilitate a £1,000 DB Board!

I totally agree with Dave sparks here....just think of the total connected load here with 40 individual occupied offices pulling between 2-5KW.