HMO wiring advice

[codamol]

Hi all,

Recently looked at an HMO (basic 1 or 2 room flats), currently run as 60A main switch to 16mm T+E for each flat.I have noticed that the basement lighting and sockets is taken straight from the main for flat 3, told landlord that is very "^

 

[steptoe]

is this TT ?

or why the need for 100mA td RCD?

are the submains surface or buried?

etc etc etc.

much more info required please.

itfr

 

[codamol]

It is TNS, not TT.

Submains are to each flat, not to each floor.Definitely not surface mounted, could be going through anything, havent investigated further, so buried.

Earth bonding all over the place in basement , ive not had anything apart yet to do any tests.Visual check that earth is in fact connected to main incoming cable, but nothing further.

5flats in total, plus the basement which is the landlord's.

Only 3 or 4 circuits to a flat(shower and/or cooker,ring final and lights), apart from Flat 1 which has 6 i think, back of cupboard and duff torch so might be 7.

Might be my mistake on the Time delay RCD, i can get my self confused, i thought i read that there should be protection on the cable from incomer to flat in event of earth fault if the cable wasnt SWA.Ill recheck on that, i was trying to read while wife and kiddy were distracting me.

**EDIT** the TD RCD was for discrimination if i read correctly and to provide protection for the submain to the flat. ...but i could be wrong

Landlord has told me the meter is being changed next thurs.

Not really sure of anything else i can tell you that would help.

itfr? unsure, checked acronyms but there are lots.

Off to double check my reading comprehension, ask away and ill try to answer.Back soon ish

 

[batty]

If 16mm cable is buried it will require 30mA RCD protection but if you do that you will not have discrimination in flat. Swa is a better option as that will not need RCD protection as its TNS as long as loop is low enough for 60 amp fuse.

 

[steptoe]

If 16mm cable is buried it will require 30mA RCD protection but if you do that you will not have discrimination in flat. Swa is a better option as that will not need RCD protection as its TNS as long as loop is low enough for 60 amp fuse.

+1

 

[Lurch]

16mm 6242Y surface mounted may be a better option than SWA depending on the routes, easier to get a bunch round a corner easier and if they are in trunking they'd be more pleasing on the eye if there are more than 1 or 2 in a run together.

 

[codamol]

Couldnt find what i think iread but

Swa is a better option as that will not need RCD protection

i might have read something similar to what batty wrote here and maybe then convinced myself that nonSWA needed rcd protection then added the discrimination on top.Not really sure what i was thinking to be fair.

I personally prefer the surface/trunking mounted idea which i think would be cheaper materials wise.I shall have to see if landlord is ok with that route as the other is not to the regs.

Disturbed sleep from 3year old really takes it outta you for brains.

Thank yous all round.

Quick question tho, would i need a switch fuse or get an MCB? Thinking if it was to blow then easier for landlord/tenants to flick switch to reset circuit.

 

[Lurch]

It would be unlikely for a 60A fuse to blow on a submain to a flat with not a lot of loading. The MCB would be more likely to trip when you didn;t want it to TBH so I'd stick with HRC's to protect the distribution circuit.

 

[batty]

Totally agree with Lurchio on this had and incident today were I was working.

Kennel maid which mashes the dogs poop up was smelling a bit and it was not poo anyway it tripped the c16 breaker but left the 13amp fuse in the spur untouched. Cartridge fuses are best option on submains.

 

[codamol]

So would you recommend i leave say a couple of spare fuses, just in case? or tell landlord/tenants to call me if it did blow out.I trust your judgement on it not blowing, but things happen.

I personally wouldnt trust the tenants with a butter knife let alone have them try fitting fuse, 3 of the 5 flats were drunk before lunch when i was there last.

And thanks again.

 

[batty]

So would you recommend i leave say a couple of spare fuses, just in case? or tell landlord/tenants to call me if it did blow out.I trust your judgement on it not blowing, but things happen.I personally wouldnt trust the tenants with a butter knife let alone have them try fitting fuse, 3 of the 5 flats were drunk before lunch when i was there last.

And thanks again.

My house has a 60 amp main fuse been like that for 60 years and has never blown. It takes a lot to blow a 60 amp cartridge fuse but just keep a few spares.

 

[codamol]

Will do, thanks again everyone.

...anyone wanna buy some time delayed RCDs... just kidding

 

[Lurch]

I wouldn;t leave fuses there for anyone to start playing about having a bash at changing them, especially as it doesn;t sound like there's anyone there competent enough. If there's a fault and the fuse blows there's likely to be a reason that will need looking at first.