location of switchfuse

TTbangbang · Oct 14, 2008

Good day sparkies,

If I have: [cutout -> meter -> isolator] -> 30mA RCD 5m away -> Henley block shortly after which splits the tails into CU no.1 0.1m away, and CU no.2 10m away. The DNO allows 5m of unprotected (as in switchfuse) meter tails.

Would this be bending the 5m rule by having the RCD at the end of the 5m allowed length rather than the CU? ]

Where should I locate the switchfuse to protect the tails? ?:|

Thank you for your time

p.s I noticed that people have been donating. What does this go towards?

Apache · Oct 14, 2008

The donation is for our silver trophies. No advertising so contributions to the upkeep of the village hall, so to speak.

If you are allowed 5m unprotected in your example above you only have 5m unprotected. What's the problem?

I'm not a spark mind.......

TTbangbang · Oct 14, 2008

The donation is for our silver trophies. No advertising so contributions to the upkeep of the village hall, so to speak.

When I click on your trophy I get a page not found ?? So where does the money go - to the administrators? I would very happily donate if the money was going to the helpful people in this forum (you know who you are :x :x:x)

If you are allowed 5m unprotected in your example above you only have 5m unprotected. What's the problem?

Are you saying that because there is a 30mA RCD at 5m, I don't need a switchfuse for the 15m of tails going to the second CU? ?:|

I'm not a spark mind.......

Nor am I, unless the-qualification-that-must-not-be-named is allowed

Apache · Oct 14, 2008

When I click on your trophy I get a page not found ?? So where does the money go - to the administrators? I would very happily donate if the money was going to the helpful people in this forum (you know who you are :x :x:x)Admin gets the money, as far as I know to keep the forum running. If you PM him I'm sure he'll explain. There are inevitable running costs, excluding the time element

Are you saying that because there is a 30mA RCD at 5m, I don't need a switchfuse for the 15m of tails going to the second CU? ?:|

Yea - why not?

Nor am I, unless the-qualification-that-must-not-be-named is allowed you too have the ladybird book - good

steptoe · Oct 14, 2008

IMHO it would be good practice to have anything over 2m in T&E, protected by switch fuse of course,

what is your earthing arrangement? makes a difference as to whether it would be SP or DP protection.

you deffo need protection of some kind for your CU2,

its really not a good design you have?

what sort of loading do you have and what size are your TAILS?

thanks, Albert.

ps, protecting everything with ONE 30mA RCD wouldnt IMHO comply with 17th, as regards nuisiance to other circuits.

TTbangbang · Oct 14, 2008

Thanks for your thoughts Steptoe.

IMHO it would be good practice to have anything over 2m in T&E, protected by switch fuse of course, what is your earthing arrangement? makes a difference as to whether it would be SP or DP protection.

It's TT, hence the RCD at the front. New RCBOs replacing the MCBs will be single pole.

you deffo need protection of some kind for your CU2,

Thanks for the confirmation. Where should a switchfuse be best placed? As close to the isolator as possible or at the 5m DNO limit?

its really not a good design you have?

It's a very big sprawling house. By having a CU 10m away, I would reduce the number of circuits (8) coming from the first one (which has 9 circuits), hence reducing the cabling cost and voltage drop. Would welcome any alternative ideas, there's beer in it for you

Guiness Drink

what sort of loading do you have and what size are your TAILS?

Tails are wee wee at 16mmsq, BS1361 fuse is 60A. Asked for an upgrade to 100A and they've offered to change supply to PME as well (not sure about that, would have to change my name :^O ).