Mains

[APE37]

Just wondering if any can advise. I am looking for time / current graph for bs1362 typeII 60a as I have a 10mm main earth and wish to use adiabatic as is a TNS to ensure the 10mm is sufficient with 16mm tails 10mm main earth and 10mm main bond. Also a Henley block is installed supplying a small Wylex 3036 board with 10mm tails with a 4-6 mm main earth. Can I note on cert or will I need to update. This will not be touched . I intend to install a light in under stairs cupboard for my sister, as she has seen one I have installed and wants one. But not sure on the tails in the consumer unit that I will be looking to extend the circuit in and not came across a 3036 board with 10mm tails and 4-6 mm main earth, as my work is new domestic, and just making sure all is ok.
I believe a 1362 type II 60a has been replaced by bs 88-3 but in the graphs in byb it is a 63 a fuse and not 60a so just looking for clarification as I use normally table 54.7. Ie 25 mm tails, 16mm main earth and 10mm bonds.
cheers

APE

 

[Lucien Nunes]

bs1362 typeII 60a

BS1361 perhaps?

 

[APE37]

Doh!! Thanks for that. 1361 type II 60a. Was trying to type as quick as poss as I only seem to have a certain amount of time to post what I type, and I type really really really slow.
Cheers L N.

 

[Richard Burns]

View attachment BS1361 time current curve Cooper Bussman LR85.pdf
The Time current characteristics would be specific to the manufacturer of the fuse although they are all within the appropriate standard limits..
however to give some indication of likely values this is one for cooper bussman LR85 fuses to BS1361:1971

 

[APE37]

Another quick q the meter and consumer units are installed in a meter cupboard that you find on an external wall, but this is in the hallway. What the previous electrician done to get the consumer unit that I will need to access to fit is used what I can only describe as a skeleton consumer unit, but they have installed it up the top in the meter cupboard and have cut the top and sides and slotted the bottom to accommodate the tails and main earth and main bond conductor. And the top is out to allow cables to enter. The front is big enough to cover so no fingers or hands can enter so using the meter cupboard I feel that IP ratings are ok but what I feel a bit unsure about is that it is so high up tight to the top of the cupboard it is difficult to remove the lid without bending it to remove and to gain access to the conductors and there also is not a lot of room to allow me to disconnect and test, I have managed to remove cover and put back on, and also pulled conductors out and put back in to do preliminary tests, but it is difficult and tight and I need to bend the front cover. I feel that this would be in breach of access regs I.e 132.12. But as I can just get the cover off and get to terminations to test, can I still consider to install the equipment as I did not install the consumer unit and I cannot move it. I suppose I am asking what would you guys do? Unfortunately not seen anything like this before and see to all new stuff so before I commit to do works I just thought I would get some opinions.

chees
APE

 

[APE37]

Thanks R B that's a big help . Cheers

APE

 

[Richard Burns]

The set up sound like a typical metal encased supply once common in some houses, they are a nuisance if an upgrade is required and it sounds as if the previous electrician has done the best he could in limited space. The original consumer units were a good fit but hopeless to improve/expand.
Get used to having limited space, the access regulations often do not seem to have been addressed in many cases!
If there are options for removing more of the surround to make removing the cover easier this might be a good thing so long as you are not exposing the wiring and live parts.

Remember you are responsible for what you install only, the existing installation must just be safe for you to connect to and the earthing and bonding should be adequate for the protection required.

 

[APE37]

Hi RB,
thanks for the advice. Yes you are right, it is something I will have to get used to. it is just I am a bit ham fisted I suppose.Just wondering regarding the little 3036 consumer unit, the earth seems small to me but if I don't touch can I just note on cert? It seems as though if I have done my adiabatic correct it may just be the correct size. But as I have not seen what that unit does and I am not touching if I go over my calcs again and find that may be insufficient, can I still note on the ticket. It just seems as though a light is wanted and I have come in and gone oh this don't look right and that don't look right and the job may explode and I don't want to do unnecessary work and people think oh I only wanted a light , and now I need X,y,and z. Sorry I may be being silly but I may be using this as a minor work for yearly assessment as it is within 15 mins form me and the assessor usually is adamant the jobs need to be as close as poss from my place, and don't want to get pulled on it what I have done.
Cheers for all the help.

APE

 

[Richard Burns]

Generally in a modern installation you would see the larger sizes of tails and earth, but not in older installations.
However since you are checking if things are OK this is good as you will be able to justify your choices with the assessor.
If you can say you have considered the access arrangements and have made a comment on the certificate that access is tight but possible, then they should be happy with that as it is impractical to entirely relocate a consumer unit to add a light.
Your earthing does need to be suitable for the installation and so long as your prospective earth fault current is above 400A then the 4mm² main earth on TNS should be OK.
If it is straightforward to replace the main earth with at least a 10mm² cable then this would look like you have planned for the future in case the supply is converted to PME.
Overall it is going to be a fiddly job with lots of inconvenient little annoyances, as with almost all retrofits, but can be done fairly straightforwardly and within the regulations.

 

[APE37]

Hi R B, thanks for the help.
sorry not got back sooner, but I have been in hospital for most of today with my mum as she is not well at the moment. I don't have the figures in front of me as they are in my tester case but the Ze was 0.20 ohms and PEFC was 1.26 or 1.28Ka off the top of my head, so is well above 400A. May deem that satisfactory ( once I go over calcs) for the moment for the little board that I am not touching, as at the moment I think I will need to approach this job as an if it ain't broke don't fix it situation at the moment, as I have a lot of stuff going on with my mum and dad as he is unwell as well with a suspected brain tumour, and my sister don't want to spend the money, so as long as it is deemed ok and I am able to use for assessment, I am happy to commit to carrying out the said works.
once again thanks for all the help and advice, especially to Richard Burns.
Regards
APE