3phase dis inb domestic setup

[J.C.E]

looked at a rewire of a 4storey property today (lower,ground,1st,2nd)
they is a 100a 3ph head on lower floor- and there is 2x seperate SP c/u (think there use to be 2x flats)

but is now going to be one house

best option?... to install something like a 8way 3ph amd3 dis board by the head on lower floor and have all my circuits off rcbo's off that (balancing the load evening across the phases)

probaly do circuit wise:

lower floor lighting 6a 1.5
ground lighting 6a 1.5
1st+2nd floor lighting 6a 1.5
lower ground power 32a 4mm radial
ground power 32a 4mm radial
1st floor power 32a 4mm radial(with 2x 3m2 UHF kits)
2nd floor power 32a 4mm radial (with 1x 3m2 UHF kits)
kitchen ring 32a ring/radial
Indcution Hob 32a 6mm
Oven 20a 2.5mm
MW 20a 2.5mm
I.H 16a 2.5mm
Boiler 16a 2.5mm
Alarm 6a 1.5mm
Smokes 6a 1.5mm

no 'building' work is being undertaken as in extensions etc- so no building inspector- would I need a system grade A fire system as a large house or will I be fine will LD3 (smokes in 4x halls and heat in kitchen- all interlinked)

 

[bigspark17]

Why 1.5mm on lighting?

 

[Strima]

You'll struggle to balance 3Ph with all those 1Ph circuits.

Have you done your max demand calculation?

Could you get away with 100 amp 1Ph supply?

 

[Spoon]

How come you are putting the smoke detectors on their own circuit?
It's it best to put them on a lighting circuit, then you will know if the RBCO has tripped?

 

[Deleted member 105166]

I would separate 1st & 2nd floor lighting onto separate circuits, otherwise when the RCBO trips, it will be completely dark when coming down from the 2nd floor!

 

[J.C.E]

Why 1.5mm on lighting?

just 2nd nature i guess- could drop down to 1.0mm....

 

[J.C.E]

You'll struggle to balance 3Ph with all those 1Ph circuits.

Have you done your max demand calculation?

Could you get away with 100 amp 1Ph supply?

as best as possible
split power radials, lights have a cooking appliance on each phase- should be even enough on a domestic enviroment no?

 

[J.C.E]

How come you are putting the smoke detectors on their own circuit?
It's it best to put them on a lighting circuit, then you will know if the RBCO has tripped?

also lose your smokes if you lose your lights.....swing and roundabouts I guess

 

[Octopus]

also lose your smokes if you lose your lights.....swing and roundabouts I guess

Smokes have batteries, so you don't lose them- I never put smokes on their own circuit.

Why 16A for the boiler?

 

[J.C.E]

Smokes have batteries, so you don't lose them- I never put smokes on their own circuit.

Why 16A for the boiler?

not sure which system/setup there are having as yet- guy doing boiler is covering control wiring etc

 

[Deleted member 105166]

Just noticed, No showers?

As your client already has a 3 phase supply, I recommend keeping it, certainly for a 4 storey house, where future demand may increase.
They'll probably want a couple of meaty car charging points in 3-5 year's time.

 

[J.C.E]

Just noticed, No showers?

As your client already has a 3 phase supply, I recommend keeping it, certainly for a 4 storey house, where future demand may increase.
They'll probably want a couple of meaty car charging points in 3-5 year's time.

not electric showers no

i was thinking the high cost of needed rcbos, and not quite 100% even balance across phases outweights- possibly blowing the 100a single phase and having to add new single phase boards in at a later date

 

[Octopus]

not sure which system/setup there are having as yet- guy doing boiler is covering control wiring etc

Never seen a gas boiler which needs a 16A supply!

 

[J.C.E]

any advise on what fire grading is needed for a large 4storey house?
exisiting building just having a rewire- no structual alterations

 

[Octopus]

This house is never going to get anywhere near 100A

 

[J.C.E]

Never seen a gas boiler which needs a 16A supply!

likely 6a mate- just poss allow for a 16a radial for another spur or 2 for the plumber.....

 

[davesparks]

Smokes have batteries, so you don't lose them- I never put smokes on their own circuit.

Why 16A for the boiler?

Because a 16A radial is the smallest standard power circuit and it is the most common circuit to be installed to feed a single small load appliance.

 

[Richard Burns]

any advise on what fire grading is needed for a large 4storey house?
exisiting building just having a rewire- no structual alterations

You need a fire risk assessment to properly decide on what grade of FDAS you should install.
If the house is old and not being renovated then the risk may be greater and consequentially need a more robust system. If the house is of conventional high quality build then a grade D LD3 should be acceptable, unless the plan is to use the house for multiple occupancy.

 

[willy fixit]

Because a 16A radial is the smallest standard power circuit and it is the most common circuit to be installed to feed a single small load appliance.

Could use the unused 1.5mm you bought for the lighting as long as it's ref B, C, 100 or 102.

 

[Gavin John Hyde]

with a property like that (over 2 stories)the people who mortgage/insure it and maybe even local council may insist on certain types of fire alarm, sound out the local fire brigade, they all have somebody driving round to offer advice and it is less aggro than the council and free aswell.
Having done quite a bit of work on multi storey town houses, most of them listed then we have had to ensure the cabling was all fire protected, fire blocks between floors, interconnected smokes/heats as a minimum and if more than 4 floors install emergency lights in the event of power failure, as if you are on 4th or 5th floor its a bit of a trek in the dark to get to basement to reset things. Always had another firm install the fancy fire alarm system when required as the firm I sub contracted for had lots of people on call.
Also you might want to check with the local building control as changing 2 flats back into 1 dwelling can come under a lot of different areas, regardless of what it is now, you are in effect creating a new dwelling as far as council are concerned. without the certificates from building control showing its up to standard and complies the property could be non-mortgageable and find insurance firms wont touch it.