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hi all,

Looking for some advice on the main fuse for a property I’m developing. It’s going to have 6/7 studio rooms, all with microwaves and potentially a hob.
Set over 3 floors if I were to have a separate light circuit for each of the 7 rooms at 3amps per room, that’s 21amps at full capacity,
A 15 amp ring on each room that’s 105amps,
Add just those together and that’s 126 amps at full pelt, is the 100amp fuse not sufficient for this? If it isn’t can I get the electrical board to put a bigger fuse in say 150amps? Is there a calculation I can do to see what fuse I need?

Thanks!!
 
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TJ Anderson

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What electric hobs are you proposing?

What are you doing for heating and hot water in the building?

3A lighting per room? Are they having floodlights?

15A ring?
 
Last edited:

Andy78

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You should get electricians involved at this stage to help you design this project. But at the first glance a 100A single phase supply, if indeed that is what you have actually got, for 7 independent units with electric cooking facilities does not sound a great start.
 
  • Thread Starter Thread Starter
  • #4
What electric hobs are you proposing?

What are you doing for heating and hot water in the building?

3A lighting per room? Are they having floodlights?

15A ring?
Not definitely going electric may go gas or use the plug in ones that are freestanding. There will only be one centre light in the room, a couple of drop down lights, an en-suite shower room light & fan, plus maybe a spot light over the kitchen all LED, 3amps is really just an example although not sure if I’ll be ok with less. As for the ring main per room 15amps is abit of a rough guess right now, do you think I would need more/less? There will only be 5/6 double plugs per room no washing facilities, using an unvented cylinder tank system for water
 
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  • #5
You should get electricians involved at this stage to help you design this project. But at the first glance a 100A single phase supply, if indeed that is what you have actually got, for 7 independent units with electric cooking facilities does not sound a great start.
Thanks Andy, will certainly be taking advice from a fully qualified spark
 

Matthewd29

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Also I very much doubt they will put a 150a fuse in. 100 will probably be max for standard single phase supply if it is even 100a could be 80 or 60
 

TJ Anderson

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Not definitely going electric may go gas or use the plug in ones that are freestanding. There will only be one centre light in the room, a couple of drop down lights, an en-suite shower room light & fan, plus maybe a spot light over the kitchen all LED, 3amps is really just an example although not sure if I’ll be ok with less. As for the ring main per room 15amps is abit of a rough guess right now, do you think I would need more/less? There will only be 5/6 double plugs per room no washing facilities, using an unvented cylinder tank system for water
Most HMO's go gas central heating and indirect unvented cylinder. Put as much on gas as poss to reduce electrical load. From a design current point of view, a 6A lighting allowance would be more than adequate for whole building but would be spread over circuits to reduce the disruption from a single circuit fault.
Rings are standard circuit and 32A. They may well be utilised in your job. Central heating will make people plugging in heaters unlikely if you are not tight with programmer lol!. Without heaters and hobs your allowance per room would be more like 5A each realistically. MCB devices protect the cabling supplying these demands, the sum rating of the MCB'S does not equal your demand, if that makes sense :)

Get an experienced spark round and thrash out a plan, you can get a lot onto a single phase supply with a good design!!
 
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  • #8
Most HMO's go gas central heating and indirect unvented cylinder. Put as much on gas as poss to reduce electrical load. From a design current point of view, a 6A lighting allowance would be more than adequate for whole building but would be spread over circuits to reduce the disruption from a single circuit fault.
Rings are standard circuit and 32A. They may well be utilised in your job. Central heating will make people plugging in heaters unlikely if you are not tight with programmer lol!. Without heaters and hobs your allowance per room would be more like 5A each realistically. MCB devices protect the cabling supplying these demands, the sum rating of the MCB'S does not equal your demand, if that makes sense :)

Get an experienced spark round and thrash out a plan, you can get a lot onto a single phase supply with a good design!!
Thanks for the great reply :)
My plan though is to have each room on it’s own meter, there’s a EU legislation that actually says each tenant needs to be able to see their own usage individually. It’s not currently enforced although could be in the future (regardless of brexit), so I’m more inclined to wire each room individually. What would your take be on the best way of doing it that way?
 

GBDamo

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hi all,

Looking for some advice on the main fuse for a property I’m developing. It’s going to have 6/7 studio rooms, all with microwaves and potentially a hob.
Set over 3 floors if I were to have a separate light circuit for each of the 7 rooms at 3amps per room, that’s 21amps at full capacity,
A 15 amp ring on each room that’s 105amps,
Add just those together and that’s 126 amps at full pelt, is the 100amp fuse not sufficient for this? If it isn’t can I get the electrical board to put a bigger fuse in say 150amps? Is there a calculation I can do to see what fuse I need?

Thanks!!
One Person of colour for every ten employees.
One disabled person for every ten employees.
One gay Man for every ten employees.
One gay Man who self identifies as a woman for every ten employees.
One straight Man who self identifies as a woman for every ten employees.
One gay Woman for every ten employees.
One gay Man who self identifies as a woman for every ten employees.
One straight Woman who self identifies as a man for every ten employees.
One Person who is gender fluid for every ten employees.
One Religiously diverse person for every ten employees.
Eleven women for every ten employees.

Think that covers it.

Oh, nearly forgot, one bloke to do all the work.

Hope that clears it up.
 
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