CU feed

[coolcatkelso]

I apologize, it was meant to be 6mm not 16mm

 

[ban-all-sheds]

Ah - OK.

 

[coolcatkelso]

So I can install with 6mm to the new cu. Is the working of the load fair? Watts / volts = amp? So the pc is 800w / 230v is 3.47amps?

So if the office in total is 31.6 and the breaker is 32amp, should I up that to 40 to allow anything else to be plugged in, ie Hoover?

 

[ban-all-sheds]

Hopefully this will illustrate the "unknown unknowns" problem you have.

Many other sizes of cable are available.

As for the size and type required:

1. what is the total load for this new consumer unit
2. how long is the cable from the supply to the consumer unit
3. how / where will the cable be installed
4. what type of earthing is provided at the supply
5. what will the cable be connected to at the supply end
6. are there any extraneous conductive parts at the office/garage?

You sort of answered some of those.

You said nothing about #4 or #6. Is that because you don't know anything about supply earthing types, don't know that there are different ones, and don't know why it might matter? Do you know what an extraneous-conductive-part is? Do you know why it might matter if there are any?

If flameport hadn't mentioned them, would you have had any idea that you needed to consider these factors when designing this installation? Would you have thought to ask about them?


This is the problem you face in trying to do work like this on the basis of asking questions about the things you think you need to know - it all falls apart when you have unknown unknowns, because you won't ask about things you don't know if you have no idea that you don't know them and no idea they even exist.

 

[coolcatkelso]

1 - answered
2 - answered
3 - answered
4 - earth at the supply, I have no idea as there's earth's everywhere supplies by Scottish power
5 - the cable at the supply end is currently connected to a 32amb MCB (installed last year by housing)
6 - the cu is metal, all cabling which is visible is installed in plastic conduit (surface mounted) sockets are all plastic secured surface mounts on breeze block.

Not sure how to answer the earth one to be honest

 

[ban-all-sheds]

There are none so blind...

#4 - So before you started designing this installation you did not know what type of supply you had and you did not know that it might matter. You never thought to ask about it because you had absolutely no idea that the issue existed. This is why you cannot carry out work like this by asking questions about what you think you don't know.

#6 - none of those are anything to do with extraneous-conductive-parts. You do not know what those are. You have never heard of them. You do not know that they might matter, or why. You never thought to ask about them because you had absolutely no idea that the issue existed. This is why you cannot carry out work like this by asking questions about what you think you don't know.

I've focussed on those two related facets because they were already raised, they went right over your head, and they illustrate very well why you cannot do electrical work of this magnitude.

There may well be other things which you don't know you don't know and therefore won't ask about.

Nobody is born knowing these things - there is no shame in being ignorant of them but that's why I keep saying what I do about you thinking that asking what occurs to you is enough.

It's why I said "installing new CUs, outside supplies, submains etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does."

It's why TTC said "You really have no idea, do you."

Please get an electrician.

 

[coolcatkelso]

I get your point, but in my view, what's already there has been there for X number of years and inspected and passed testing annually, however there are only 3 sockets in the garage and 2 Double sockets in the office as radials.

I've installed a ring to the garage with a few more sockets and a new ring in the office with more sockets to eliminate the need of four ways connects to four ways.

The supply from the house is earth via the earth bar at the top of the cu and that follow through to the first socket in the garage. I'm just simply going to disconnect those sockets, and put the wires in the appropriate places , live to live, neutral to neutral and the earth from the supply to the earth bar. Following the same route as the existing sockets etc.

My understanding is clearly wrong in terms of conductive parts, I assumed it was something that could become live if a fault is present hence why I said, cables are covered with conduit, metal cu will be earthed.

I do understand that an electrician is required, and one will be here next week, but I would rather do as much as I can myself to lower costs.

I won't be connecting anything to the house cu but I don't mind playing with the dead wires ready for the guy who will or I should expect anyway him to inspect and test what I have done.

 

[coolcatkelso]

I'm certainly not asking what I need Sonu can switch it on myself.

It's true what they say little knowledge is dangerous, but I do enjoy learning new things and always set the challenge, bugbid thought I'd ask a few simple questions in here to help me along the way.

 

[ban-all-sheds]

I've installed a ring to the garage with a few more sockets and a new ring in the office with more sockets to eliminate the need of four ways connects to four ways.

When you did that did you have good cause to believe that the fault loop impedance would be OK? "what's already there has been there for X number of years and inspected and passed testing annually" is irrelevant - you were responsible for the new stuff.

The supply from the house is earth via the earth bar at the top of the cu and that follow through to the first socket in the garage.

Not an answer to the question you've been asked. You still have no idea what it meant, you still have no idea why it matters. You still do not understand the problem of unknown unknowns.

My understanding is clearly wrong in terms of conductive parts, I assumed it was something that could become live if a fault is present hence why I said, cables are covered with conduit, metal cu will be earthed.

You've already shown that you have some dodgy misconceptions - what if you get something wrong because you have no idea your knowledge is wrong? What if you miss something because you simply have no idea it even exists, and just don't realise you don't know it?

I do understand that an electrician is required, and one will be here next week, but I would rather do as much as I can myself to lower costs.

Have him instruct and supervise you as he sees fit - it will be his name on the paperwork.

I get your point,

 

[oldbutnotdead]

One critical point that no-one has mentioned- you say the place is owned by a housing association which implies that you are a tenant. So, why are you wasting money making improvements/alterations to someone else's house and have you sought the property owners' permission to make these alterations (and if so have you complied completely with the conditions they will have attached to any such permission).

In case you think this is a technicality, think on- you could be charged with causing criminal damage (which is a proper crime rather than a civil offence), you could be evicted for breaching the terms of your tenancy AND find yourself ineligible for assistance from your local council (due to intentionally making yourself homeless by breaching the terms of your lease). Add that to your guess and go approach and suddenly b-a-s's suggestion of getting someone with accredited qualifications to do the job sounds like the best way to achieve your objectives

 

[John D v2.0]

In case you think this is a technicality, think on- you could be charged with causing criminal damage (which is a proper crime rather than a civil offence), you could be evicted for breaching the terms of your tenancy AND find yourself ineligible for assistance from your local council (due to intentionally making yourself homeless by breaching the terms of your lease)

?? According to who?

 

[scousespark]

I won't be testing it, I will be getting a electrician in to inspect and test but obviously want to save as much as possible

Good luck there mate.

Installing the consumer unit was easy, installing the ring circuit and sockets was easy, I'm simply asking a question as to which is best practice, 10mm or 16mm armoured.

You have totally missed the design phase and everything you have posted screams out that you are out of your depth.

 

[scousespark]

The 32amp in the house which currently feeds everything but o my if I plug in the circlular saw at 2600w and a 1200w Hoover, but I think it's because the socket they are plugged into runs of a plug plugged into another socket .

The trip isn't the issue tho once I've connected the new board up as I don't think it's caused by the 6mm cable

You have a feed to your garage, limited to 32amps. The breaker has tripped because the load in your garage is more than 32amps (I am ignoring the tripping curve on purpose). Changing the circuit will not change the load, so you will still see trips.

 

[coolcatkelso]

Right electrician has been out today and asked to see the permission letter from the association, he's happy with that, he's happy with the ring circuit I've done and the installation of the cu, he's said he will use 10mm swa and a new 63a MCB.

 

[Taylortwocities]

Ah. You don’t need us any more then?