Protective device

peek a boo stoo · Jan 22, 2014

Hi all need some help,
I was called to a job to do some rectification work after a so called sparkey half wired a house.
He decided to run a 10mm T+E from a Henley block located in a cellar to a second C/U three floors up, I'm going to have to change the 10mm to 16mm.
My question is what do I use as a protective device once I have started remedial work. I was going to use a 63A switch fuse however the cable runs through stud walls so could do with it being rcd protected too.
Been racking my brains but I think I have over complicated it for myself.

Guest55 · Jan 22, 2014

whats the expected load of this 3rd floor ?

what diversity are you applying ?

looking in my OSG shows that 10mm t&e ref C carries............

wait for it..........

64A !
amazing lol !

and even if you have to de-rate the cable , would 50A not do the job so you can keep the cable and keep costs down for the customer ?

telectrix · Jan 22, 2014

another point is the bonding. if required, might need a separate bonding conductor.

peek a boo stoo · Jan 22, 2014

The customer has plans to add more circuit at a later date but isn't sure when he wants to do it hence the 16mm rather do it now rather than later. However you're right about the 64A that was never in doubt.
However my question still remains unanswered as to what to use to protect the cable running up.
If it was in a commercial or industrial set up I'd use a switch fuse.
However I'm uncertain in this case.

telectrix · Jan 22, 2014

only needs RCD if buried in wall/s <50mm etc.

Plonker 3 · Jan 22, 2014

Why not run a SWA if it needs to be run in walls and would require RCD protection if run in T&E

telectrix · Jan 22, 2014

if you're going to uprate to 16mm, then go with dilb and SWA. then you get a decent cpc.

Octopus · Jan 23, 2014

RCD in cellar, whole 3rd floor trips - whoops down you go. That said, it would be a good way to get fit and loose a few pounds when nuisance tripping starts!

MDJ · Jan 23, 2014

My question would be why did the first spark only do half a Job? the customer may be a bad payer, I would find out who the first guy was and have a chat to him just in case. There is a bad spout of customers mentioned on here lately who do not like paying their bills, otherwise it does pain me to agree with what Biff said in post 2 lol

Hawkmoon · Jan 23, 2014

peek a boo stoo said:
Hi all need some help,
I was called to a job to do some rectification work after a so called sparkey half wired a house.
He decided to run a 10mm T+E from a Henley block located in a cellar to a second C/U three floors up, I'm going to have to change the 10mm to 16mm.
My question is what do I use as a protective device once I have started remedial work. I was going to use a 63A switch fuse however the cable runs through stud walls so could do with it being rcd protected too.
Been racking my brains but I think I have over complicated it for myself.

I am always wary going to a job 'half done' by a previous electrician - you only have the customer's word on what happened (spark may not have received a stage payment or something).

The 10mm may prove to be ok - obviously no switchfuse but that may have been a later intention (had the previous guy finished the job).

Edit: MDJ - Got in before me! Damn my slow typing!!!