3 phase advise

[m4fiaafg]

basically i am starting a job on a large domestic property, which has a three phase supply in the basement. i am planning to put individual consumer units in each floors by taking an individual phase to each floor. please, can anyone give me some more ideas. please if you can in as much detail

cheers

 

[Darkwood]

The main aim with 3ph is to achieve a balanced load so if this is still achievable with a phase per floor the it ok, but not knowing the installation its hard to comment too much if its possible a floor may be unused on regular occasions then the balance would be way out, lets say the kitchen and utility room are down stairs, most of the day this floor could be subject to heavy loading with floors 1 and 2 barely been used in this case it would be poorly designed and cost more to the customer to use the same amount of electric as they would a balanced load.

 

[johnstantine]

Hi
I would think an important factor would be that the the main neutral is sufficient to handle the largest possible out-of balance current, as there is no way to guarantee keeping all phases balanced.

 

[Darkwood]

Hi
I would think an important factor would be that the the main neutral is sufficient to handle the largest possible out-of balance current, as there is no way to guarantee keeping all phases balanced.

The neutral is usually equivalent in load handling than any given phase conductor so if you were to load one phase up to max and no load on the other phases this would be the max current the neutral would have to handle as adding load to any other phase would bring down the neutral current all the way down to o amps if perfect balance (although unlikely) was ever achieved on all three phases. ( The zero current would be on the incomming neutral and not the individual submain neutrals if they were single phase)

So as long as the incomming neutral is equivalent to csa of any phase conductor then this wouln't be an issue

 

[peteludman]

i would do what you are doing (1 phase per floor).
This way you will avoid any possable chance of a 415v fault if you have a phase per floor then it would only be 240v per floor.
but the stairs you will have to be careful that you only have 240V in the light switches

this would be safer

 

[Pete/2472]

basically i am starting a job on a large domestic property, which has a three phase supply in the basement. i am planning to put individual consumer units in each floors by taking an individual phase to each floor. please, can anyone give me some more ideas. please if you can in as much detail

cheers

Hi install a lot of three phase boards but have never needed to split into three boards over three floors!
if you were to put a cu on the upper floor this would have no demand during the daytime!
I just work out the total demand for the property and split the lot across a three phase board to balance the load?saves ££ alround..

 

[m4fiaafg]

Hi install a lot of three phase boards but have never needed to split into three boards over three floors!
if you were to put a cu on the upper floor this would have no demand during the daytime!
I just work out the total demand for the property and split the lot across a three phase board to balance the load?saves ££ alround..

cheers mate for the reply, i m just trying to keep my final circuits to a minimum run you see, that way ii will have to take every circuit down to the celler, which is a very big task.

 

[peteludman]

so you could you could have 415 v in the bathroom if lights ar on L1 and shower on L2
come on look for a safe installation mate

Hi install a lot of three phase boards but have never needed to split into three boards over three floors!
if you were to put a cu on the upper floor this would have no demand during the daytime!
I just work out the total demand for the property and split the lot across a three phase board to balance the load?saves ££ alround..

so you could you could have 415 v in the bathroom if lights ar on L1 and shower on L2
come on look for a safe installation mate

 

[ian.settle1]

cheers mate for the reply, i m just trying to keep my final circuits to a minimum run you see, that way ii will have to take every circuit down to the celler, which is a very big task.

What he is saying is fit a 3 phase board on each floor and balance circuits that way not run every thing back to the celler like you are thinking.

 

[Darkwood]

so you could you could have 415 v in the bathroom if lights ar on L1 and shower on L2
come on look for a safe installation mate





so you could you could have 415 v in the bathroom if lights ar on L1 and shower on L2
come on look for a safe installation mate

A 3 phase per floor isnt an issue you seem to be creating your own arguments here as a well designed installation you would put said bedroom and on-suite on one of the phases and another bedroom and on-suite on another phase and as the bathroom goes it dont matter if the lighting is on one phase and the shower on another etc 230v kills 400v kills if its designed to the regs its considered safe, its only when sockets over diff' phases are within reach of each other or light switches have multiple phases in them that a requirement to mark up 400v presents is needed, nothing more, its common practice on larger installations its just domestic dont usually have 3ph 400v.

 

[peteludman]

just going on what the niceic man wa saying to me

 

[Darkwood]

just going on what the niceic man wa saying to me

Depends from what angle he was approaching as if you have single phase items on different phases but they were within reach of each other then their is an additional risk associated with this especially in bathrooms and should be avoided in the design and has i mentioned before if designed properly you can balance the floor over 3 phase by having a phase per area so 2 phases dont exist within the same rooms. If you get pulled up by the niceic bloke for whatever reason just ask him to ref' the exact regulation ive found this helps me understand where hes coming from when ive missed something as they tend to spool things out and its easy to agree without knowing why.
Commercial offices usually have multiple phases in switches for large offices and again with sockets so to achieve good load balance but as long as theeir is marking where needed their isnt any problem in doing so.

 

[peteludman]

230v can kill and 415 is more than likely going to, there is twice as much voltage.

i work mainly with large 3 phase circuits and the inbalance of phases in a house if each floor is on its own circuit is going to be so small.

so even if you think it dont matter if you have 2 phases in same room i do.

but ok bed 1 on L1 bed 2 on L2 office on L3 bathroom on L1 kitchen on L2 living, dinning room on L3, i think this is ok if you put a 3 phase board on each floor. but dont have 2 phases in same room.

im sure you will aggree.

 

[Sintra]

230v can kill and 415 is more than likely going to, there is twice as much voltage.

It's not the voltage that kills you, it's the current.

 

[sparks1234]

It's not the voltage that kills you, it's the current.

I think you will find 400 volt stings abit and makes your eyes water