400amp 3 phase 4 wire cable sizing help.

[Fred Faulkner]

Hi guys if you could help me out with this would be much appreciated,

its for a shop within a shopping centre and the client ( Decathlon! ) require a huge
supply which i have contested but they seem to think they need this size feed.

From a ryefield board to a 400amp switch fuse within the switch room using tri rated singles
in metal trunking approximentlt 5 metres away.

Sizing of tri rated singles ?

then from the switchfuse to a 400amp MEM isolator which is 30 metres away , containment
will be ladder rack.

sizing of the 4 core armoured ?

Cheers not my strong point so help would be great.

If there is anything which you need left off il do my best to respond with it.

 

[telectrix]

somewhere between 120mm and 150mm at a guesstimate. just look up the ccc's and VD's in the osg and do the calcs. from there.

 

[Simlec]

Do Decathlon know they have a contractor with little experience?
what are your cable calc's?

 

[Fred Faulkner]

Do Decathlon know they have a contractor with little experience?
what are your cable calc's?

Nothing wrong with abit of advise this is what the forum is about,

They have paid UKPN 3grand to fit 400amp fuses and provide a bigger ct chamber
for the new 250kva supply, the shop is not very big and will have lights and say 10 a/c units
so i have asked why this size of supply is nessesary but ive been told thats what they
require etc etc

a cable which can potentially handle 360amps would be a 185mm but im asking advice to
see if i can use smaller..

Could you be of help?

 

[shanky887614]

Nothing wrong with abit of advise this is what the forum is about,

They have paid UKPN 3grand to fit 400amp fuses and provide a bigger ct chamber
for the new 250kva supply, the shop is not very big and will have lights and say 10 a/c units
so i have asked why this size of supply is nessesary but ive been told thats what they
require etc etc

a cable which can potentially handle 360amps would be a 185mm but im asking advice to
see if i can use smaller..

Could you be of help?

install ladder racking/tray and you can get away with 150mm singles or it will be a 240mm for 3phase 400amp in free air/tray


table 4d3a and 4d4a for calcs


i bet it will be cheaper to get 3X 150mm and earth than 1 x 240 multicore

 

[Sintra]

install ladder racking/tray and you can get away with 150mm singles or it will be a 240mm for 3phase 400amp in free air/tray


table 4d3a and 4d4a for calcs


i bet it will be cheaper to get 3X 150mm and earth than 1 x 240 multicore

Then you have the added implication of non ferrous gland plates and the laying arrangements of them on the ladder.

 

[shanky887614]

Then you have the added implication of non ferrous gland plates and the laying arrangements of them on the ladder.

true but the op said its only going to be 5m or so, not a problem to put in trefoil cleats etc for that distance and with that size cable im sure the op would do a proper job

 

[Darkwood]

The upstream fusing and cable size may be to meet full disrimination with the fusing within their distribution system and not the calculated load, arguing this point may make you look like a rookie if this has been designed, these are commercial premises and a fault say on a large A/C unit does not want to take all the power out because of poor design and ruin trade.

On here we appreciate it if you show us your calcs, that way we know you are trying to help yourself and not after others to do all the work for you, I'm getting the impression this is beyond your field of experience and on that note you should think hard about trying to do this work without experience, a small error can be very costly.

 

[telectrix]

ref method E ( perforated tray/ladder?etc.) gives you 330A with 150mm SWA . it's up to you to decide. too small and you'll have to rip it out. too large and you've caused your client unnecessary expense.

 

[Fred Faulkner]

So for the 30m run on ladder rack from the 400 amp switchfuse the 400amp isolator which has to be mutlicore aomoured i was calculating 185mm .

i believe i will have trouble terminating this into those outlets.. Might need to use those special crimp packs which turn and reduce to get the cores in.

 

[shanky887614]

ref method E ( perforated tray/ladder?etc.) gives you 330A with 150mm SWA . it's up to you to decide. too small and you'll have to rip it out. too large and you've caused your client unnecessary expense.

ref f with single swa gives 150mm.
ref e with 3/4c swa gives 240mm

for 400a ish

 

[telectrix]

yes, but is the design load 400A or considerably less? it might just be that a 250A supply is insufficient and they've gone for the next standard size up.

 

[Sintra]

true but the op said its only going to be 5m or so, not a problem to put in trefoil cleats etc for that distance and with that size cable im sure the op would do a proper job

30M mate

 

[Fred Faulkner]

The upstream fusing and cable size may be to meet full disrimination with the fusing within their distribution system and not the calculated load, arguing this point may make you look like a rookie if this has been designed, these are commercial premises and a fault say on a large A/C unit does not want to take all the power out because of poor design and ruin trade.

On here we appreciate it if you show us your calcs, that way we know you are trying to help yourself and not after others to do all the work for you, I'm getting the impression this is beyond your field of experience and on that note you should think hard about trying to do this work without experience, a small error can be very costly.

I understand where your coming from but im sure im more than capable in installing this work to a good standard im just asking maybe the more experienced in cable calculation to help me keep this size as small as possible as the size of cable is hard to handle and terminate as im sure youve done before.

 

[Leesparkykent]

[h=3]Multicore 90°C Armoured Thermosetting Insulated Cables[/h]Tables Apply to: H6942XL, H6943XL, H6944XL, H6945XL, Tuff Sheath,
Voltage:400V
Load:221.7kW / 400A
Length:30m
Method of Installation:In free air or on a perforated cable tray
Cable Size:150mm²