My last 'non Amd 3' CU Install.

[Dave OCD]

Put this in today, I hope it doesn't burst into flames.:tongue3: Didn't have the time to faff about and get the cabling 'perfect' as I had so much to do today but I think it's ok. With the BG boards I generally 're number' the earth bar as to me it's illogical having the CPCs running in the opposite order of the neutrals,I'll miss the insulated CUs. Sorry about the
poor photo.

 

[davesparks]

we are talking a sub 100amp single phase house supply here where the biggest supply will probably be a shower at 50amp.

with the new reg of all circuits on rcd's im not sure how many decades of leakage it would take to cause any issues on a small domestic property without tripping an rcd.

The regulations cater for all installations the same, not just little domestic installations.

As I said earlier it is the fault current which could flow which is of concern with the cpc, with a couple of thousand amps available at the point in the installation we are discussing there would be significant eddy currents.

The bottom line is, the regulations specifically require that it be done a certain way with good technical reasons, why would you want to dispute it?

 

[Dave OCD]

I notice that very few people share their board upgrades from properties that haven't been treated to a rewire beforehand. They're not always quite so easy to make them look good.

My first post was replacing the board with existing wiring , there was a 16th edition split load board there so no RCD protection on the lighting [including bathroom],oven/hob, immersion and boiler supply and the new owner wanted it updating, I agree you can never make the job look quite as good with cabling that's previously been stripped and connected but luckily whoever did the previous CU had left a decent length of tails.

 

[hasel5]

Think people are missing the point re Eddy Currents

Think we were taught only live condutors need to be in the same Knockout/hole when passing through metal so L1,L2,L3 and neutral

Tin Hat on

 

[davesparks]

Think people are missing the point re Eddy Currents

Think we were taught only live condutors need to be in the same Knockout/hole when passing through metal so L1,L2,L3 and neutral

Tin Hat on

Please do enlighten us as to what the point is?

Who taught you that? Have you read the regulation concerning this?

 

[hasel5]

Point is the CPC is not a live conductor so does not need To be through the same hole /grommet or KO

 

[happysteve]

Physics doesn't care if the cpc is a live conductor or not. In the event of a fault, current will flow through the CPC/earthing conductor. Eddy currents will flow. The metal will heat up.

 

[davesparks]

Point is the CPC is not a live conductor so does not need To be through the same hole /grommet or KO

Ok, but why are you saying it only needs to be live conductors when the regulations specifically require the cpc to be included? Do you work to different regulations to the rest of us?
What do you do about the massive temperature rise of the enclosure under fault conditions?

 

[Midwest]

What did I say, we had this argument before about same hole things! JW subjected this to test in a domestic situation.

https://www.youtube.com/watch?v=hg5eZkq2KgE

 

[hasel5]

Physics doesn't care if the cpc is a live conductor or not. In the event of a fault, current will flow through the CPC/earthing conductor. Eddy currents will flow. The metal will heat up.

Yes but for how long?

 

[happysteve]

Yes but for how long?

Trying to work out if this is a rhetorical question or not... but just in case it isn't: until the fault is cleared.

 

[bigspark17]

So how is running the earth conductor in same hole going to stop this rise in temp.? I was always under impresion eddy currents were concern in line and N conductors in >200amp installs. Please copy n paste the reg on here fir those of us who dont have a big book to hand

 

[davesparks]

Yes but for how long?

Up to 5seconds if you mean the duration of the fault

Many many years of you mean how long this regulation jas existed

 

[Dave OCD]

Right ,enough of going round in circles, let's criticise the most recent CU pictures.
Nothing too bad about any of the 3 pics posted IMO, better than a lot you see out there in fact.
But I wouldn't have put 3 lighting circuits into the one MCB, with a slightly bigger board these could have been split and also via seperate RCDs, not good practice that.

 

[davesparks]

But I wouldn't have put 3 lighting circuits into the one MCB,.

Don't start that circular nonsense debate again!

 

[Leesparkykent]

So how is running the earth conductor in same hole going to stop this rise in temp.? I was always under impresion eddy currents were concern in line and N conductors in >200amp installs. Please copy n paste the reg on here fir those of us who dont have a big book to hand

521.5.1...cant be arsed to type it out though lol