T
tomomac33
Hi people.
My first post on this forum - many thanks in advance for the commitment to it, hopefully I may be able to contribute as well. For anyone who is interested, I was an Electrical Maintenance Engineer for 10 years at BAE Systems, doing anything and everything - then i chose a completely different career path, but I still try to remain as current and active in Electrical installations as feasibly possible.
I have just bought a 3 story house that is converted into 5 self-contained flats. Re-wired within the last decade as a guess, however, whoever did it forgot about the 100A Single phase cut out being upgraded. The set up isn't ideal to say the least - in Brief - A CU with 5x 45A type B breakers, 10mm T&E to each flat, local CU's and landlord meters, then all the other junk (landlord supply’s, fire alarms etc etc are fed from the remaining available ways). Some flats have Gas, allowing smaller supplies than 45A. Over time I want all electric, economy 7 heating, check meters in the basements, SWA to each flat and everything else you would expect. My initial design considerations lead me to wanting a 60A supply in each flat after all diversity considerations.
The DNO - I have no experience dealing with these chaps so I have some questions I would appreciate help for.
1. What supply do I ask for - (60A x 5 = 300A, x 230v = 69kva x 75% for diversity = 52kva?) would this be acceptable or am I way off? how do THEY calculate maximum demand based on what you tell them?
2. I don’t want to cut my own arm short asking for a supply that will end up limiting me - however the price seems to increase considerably over 60kva?
3. I have attached an image "plan" of the site - I have a few questions regarding the plan. my property is highlighted in RED (No 556). Adjacent Properties No.558 and No.2 have recently had supplies upgraded to suit what I require. However the DNO isnt able to tell me what they have been given (why they can’t do this I don’t know). BUT, on the drawing i can see they have installed a "1x150" and a "1x117" electrical ducts to encase the new supply cable which is "3C 95 SAC XC TP" Cable. I assume "3-core 95mm2 Solid Aluminum Conductor" - I don’t know what "XC TP" is referring to - maybe Capacitive reactance or twisted pairs - but this makes no sense to me?? you can also see the OLD supplies "3C 25 SAC PSC OOC" - which I currently have supplying the flats.
So:
4. What does "3C 95 SAC XC TP" equate too and what supply is this likely to be giving?
5. I assume the most the DNO will give me on my 3c 25 SAC will be a 100A cut out?
6. Ultimately - I think I am expecting to be asking for a 3 phase supply (100a x 400v x root3 / 1000 = 69kva) - but this still gives me issues balancing the phases if no further diversity is allowed - so then it would be a 120a (83kva) - and this sounds ridiculous!
Many thanks for your help in advance
Kind regards
Tom
![[ElectriciansForums.net] Experience with the DNO?](https://electricians.s3.eu-west-1.amazonaws.com/data/attachments/7/7907-e2036932baf33588714b3b47424d9c95.jpg "[ElectriciansForums.net] Experience with the DNO?")
My first post on this forum - many thanks in advance for the commitment to it, hopefully I may be able to contribute as well. For anyone who is interested, I was an Electrical Maintenance Engineer for 10 years at BAE Systems, doing anything and everything - then i chose a completely different career path, but I still try to remain as current and active in Electrical installations as feasibly possible.
I have just bought a 3 story house that is converted into 5 self-contained flats. Re-wired within the last decade as a guess, however, whoever did it forgot about the 100A Single phase cut out being upgraded. The set up isn't ideal to say the least - in Brief - A CU with 5x 45A type B breakers, 10mm T&E to each flat, local CU's and landlord meters, then all the other junk (landlord supply’s, fire alarms etc etc are fed from the remaining available ways). Some flats have Gas, allowing smaller supplies than 45A. Over time I want all electric, economy 7 heating, check meters in the basements, SWA to each flat and everything else you would expect. My initial design considerations lead me to wanting a 60A supply in each flat after all diversity considerations.
The DNO - I have no experience dealing with these chaps so I have some questions I would appreciate help for.
1. What supply do I ask for - (60A x 5 = 300A, x 230v = 69kva x 75% for diversity = 52kva?) would this be acceptable or am I way off? how do THEY calculate maximum demand based on what you tell them?
2. I don’t want to cut my own arm short asking for a supply that will end up limiting me - however the price seems to increase considerably over 60kva?
3. I have attached an image "plan" of the site - I have a few questions regarding the plan. my property is highlighted in RED (No 556). Adjacent Properties No.558 and No.2 have recently had supplies upgraded to suit what I require. However the DNO isnt able to tell me what they have been given (why they can’t do this I don’t know). BUT, on the drawing i can see they have installed a "1x150" and a "1x117" electrical ducts to encase the new supply cable which is "3C 95 SAC XC TP" Cable. I assume "3-core 95mm2 Solid Aluminum Conductor" - I don’t know what "XC TP" is referring to - maybe Capacitive reactance or twisted pairs - but this makes no sense to me?? you can also see the OLD supplies "3C 25 SAC PSC OOC" - which I currently have supplying the flats.
So:
4. What does "3C 95 SAC XC TP" equate too and what supply is this likely to be giving?
5. I assume the most the DNO will give me on my 3c 25 SAC will be a 100A cut out?
6. Ultimately - I think I am expecting to be asking for a 3 phase supply (100a x 400v x root3 / 1000 = 69kva) - but this still gives me issues balancing the phases if no further diversity is allowed - so then it would be a 120a (83kva) - and this sounds ridiculous!
Many thanks for your help in advance
Kind regards
Tom
