Workshop RCD, Radial circuit

[JohnW2]

I wonder what, in his mind, makes him think he is anywhere near competent to be installing CUs?

That is a good question.

Kind Regards, John

 

[brunoo]

I seriously doubt that such is what he was attempting to refer to - it would make little sense in terms of the rest of what we've been told (particularly in the OP).

Brunoo - what is it you've looked at, which you think is an RCD, and have seen an earth connection to it?

I frankly doubt that he was 'looking at' anything. I suspect that he has limited understanding of how these things work and thought that a circuit somehow gets an earth connection through its RCD (or MCB) - or, perhaps more likely, he was meaning that the earth connection was coming from 'the RCD unit' (which is how he's decribing the secondary CU).

And why...

The shower is on a 40A RCD in the main CU with 6MM T&E direct to the shower, I will be disconnecting this and using a 2-way 100A junction box, Then continuing with 6mm T&E to the workshop RCD unit.

Why have 2 RCDs in series?

If you read the OP, you'll see that he has used 'RCD' to refer to what almost ceratinly are MCBs. He speaks of a "40A RCD" (ex shower cct) in the main CU supplying "6A and 32A RCDs" in the 'Garage CU' he's using for the workshop, All we do know for sure (from the Screwfix link) is that this 'Garage CU' does, indeed, contain an RCD. Although the 'main CU' may be RCD protected, I don't think we've been told anything to confirm that (since I believe his reference to a 40A RCD supplying the old shower circuit in fact relates to an MCB).

Kind Regards, John

Yeah thats hit the nail on the head, Cheers John.

There is no/very minimal water in the Workshop, No taps/baths etc.

This is my main CU;

From the 40A shower breaker it goes upto the shower in 10-12mm T&E in 50x25 trunking for 10m, Then under the floor to the shower, Then into a 60A 3way terminal junction box, Then onto Garage MCB (linked above) using 6mm T&E. Then a 10M long radial circuit with the same 6mm T&E with 2 double MK sockets on.

It's all installed, tested and works fine.

Cheers for the help guys, That's NOT including 'ban_all_sheds' Troll-Off

 

[ban-all-sheds]

It's all installed, tested and works fine.

Care to scan and post your schedule of test results?

Cheers for the help guys, That's NOT including 'ban_all_sheds' Troll-Off

Well excuse me for thinking that if you're going to go around installing CUs you ought to actually know what you're doing.

Dismiss me as a troll if you like - that will be just one more example of your inability to understand what's going on.

 

[brunoo]

It's all installed, tested and works fine.

Care to scan and post your schedule of test results?

Cheers for the help guys, That's NOT including 'ban_all_sheds' Troll-Off

Well excuse me for thinking that if you're going to go around installing CUs you ought to actually know what you're doing.

Dismiss me as a troll if you like - that will be just one more example of your inability to understand what's going on.

I do apologies, I came across harsh.

Having read through a huge amount of threads on here, 99% of your posts seem to be negative towards anyone who hasn't the same knowledge as yourself.

Now, Correct me if I'm wrong, But this is a DIY forum is it not?

 

[Aragorn84]

Now, Correct me if I'm wrong, But this is a DIY forum is it not?

Perhaps, but dont you accept that some tasks are beyond the DIYer (or perhaps more correctly, SOME DIYers) to do competently?

For instance, many people will accept that Gas work should only be touched by someone registered with Gas Safe etc? If someone came on a DIY forum asking how to DIY his gas supply to a boiler, wouldnt you expect that knowledgable members would quickly ascertain that the person shouldnt be touching Gas, and will tell them so?

Similarly if someone doesnt know how to mix some cement, or lay a brick, but was determined to do all the structural calculations for his 2 story home extension and then proceed to build it himself simply by asking many questions on a DIY forum, the forum members would probably be telling him to get a builder in?

What you also forget, is regulars on here, like BAS and others, see on a daily basis, folk asking similar questions, with similar levels of competency (ie nil), and who essentially view electrical work as stringing along some cable and putting red into the red hole and black into the black hole, and think that they can take this naive view of electrical work and translate it into being able to rewire their whole house with half a clue what they're doing and without any test equipment in sight.

 

[brunoo]

Now, Correct me if I'm wrong, But this is a DIY forum is it not?

Perhaps, but dont you accept that some tasks are beyond the DIYer (or perhaps more correctly, SOME DIYers) to do competently?

For instance, many people will accept that Gas work should only be touched by someone registered with Gas Safe etc? If someone came on a DIY forum asking how to DIY his gas supply to a boiler, wouldnt you expect that knowledgable members would quickly ascertain that the person shouldnt be touching Gas, and will tell them so?

Similarly if someone doesnt know how to mix some cement, or lay a brick, but was determined to do all the structural calculations for his 2 story home extension and then proceed to build it himself simply by asking many questions on a DIY forum, the forum members would probably be telling him to get a builder in?

What you also forget, is regulars on here, like BAS and others, see on a daily basis, folk asking similar questions, with similar levels of competency (ie nil), and who essentially view electrical work as stringing along some cable and putting red into the red hole and black into the black hole, and think that they can take this naive view of electrical work and translate it into being able to rewire their whole house with half a clue what they're doing and without any test equipment in sight.

Yeah I can respect this, Particularly the Gas part.

I found this quote which sums things up in my mind..

Just for info

Building control are not interested in what Brunoo does in his own home

if he kills himself thats his fault

if he kills a visitor from his electrics its his fault

lets not get confused here.... its different for a home owner doing his own electrics than if it was me or you doing it for him

lets all give him sound advice so he does a good safe job whether we agree to it or not


I took extreme care doing this, Using voltage drop calculators to calculate required cables/de-rating etc etc

I have RCD protection on the main CU and secondary CU, I have tested these with the Test button and they work as required.

Can anyone give me some more detailed tests I can do, I don't mind buying equipment.

Thanks again.

 

[JohnW2]

I took extreme care doing this, Using voltage drop calculators to calculate required cables/de-rating etc etc I have RCD proctection on the main CU and secondary CU, I have tested these with the Test button and they work as required. Can anyone give me some more detailed tests I can do, I don't mind buying equipment.

It wouldn't be worth your buying the necessary equipment to do full and 'proper' testing just for a 'one-off' exercise - it would be far cheaper to employ an electrician. You could hire the required equipment for a day or two, but you would then have to acquire the knowledge required to undertake and interpret the tests (and, ideally, also an understanding of why/how the testswere being undertaken).

Kind Regards, John

 

[EFLImpudence]

Can anyone give me some more detailed tests I can do, I don't mind buying equipment.

http://www.fault3.com/tests.html

http://www.test4less.co.uk/results.asp?CategoryID=15

 

[bernardgreen]

I use very high powered tools in excess of 4-5KW for a few hours at a time.~~~~~~~~~~Can anyone spot any possible issues?

I assume electric motors are involved, do they have soft start controls ? If they do not have soft start then the high starting currents are likely to cause voltage dips in your house and in other houses on the same network supply phase. If these voltage dips become a nuscience to the neighbours then the DNO may "ask" you to stop using the motors.

 

[ban-all-sheds]

Having read through a huge amount of threads on here, 99% of your posts seem to be negative towards anyone who hasn't the same knowledge as yourself.

Not so - what I disapprove of, very strongly, are people who do not see why ignorance should be a bar to them fiddling with their electrics. People who think that they can do it on the basis of following put-this-wire-in-that-hole type instructions without actually having a clue why. People who think it's OK to just try things until it works, and that if it works then that's all that matters. People who refuse to accept that only asking about things they think they should ask about risks them missing things which they have no clue even exist

Now, Correct me if I'm wrong, But this is a DIY forum is it not?

It is, but unlike almost every other field of DIY, where substandard results aren't a major issue, with electrical work you cannot afford to be less competent than a qualified electrician. That doesn't mean you have to know as much as he does, but it does mean that you have to know as much as he does about the particular job you've chosen to do.

It means, for example, that if you want to go installing CUs, you need to know that this:

I have RCD protection on the main CU and secondary CU, I have tested these with the Test button and they work as required.

does not do a proper test of the RCD, and that the proper test should be done before you put the circuit(s) into use.

Can anyone give me some more detailed tests I can do, I don't mind buying equipment.

http://www.tlc-direct.co.uk/Book/8.1.1.htm

 

[brunoo]

Thanks for the very informative posts.

I am prepared to learn about this and hire the equipment myself.

My hire list so far includes;

Megger MFT 1720
Seaward Solar PV 100 Ultimate

For both, For 2 days, It's around the £40 mark which seems reasonable to me..

I'm confident in using the MFT, Though I don't fully understand all of the tests required yet.

I understand this tool tests the loop resistance, phase to phase loop test, Performs a high-current test and a polarity test*

*I dont quite understand the Polarity test, Is this simply to test neutral/earth connections are made/secure to all circuits?

I've not read much on the PV testing kit yet, Though I understand it tests the continual earth measurement down to 10ohms. Still a lot of reading yet to do on this.


I realise learning the complete testing procedure is going to be a huge learning curve, The is a non-issue and I feel fairly confident.

Or should I just get a sparky in to check my work and tell me everything's fine ( or not ).

 

[riveralt]

I'm confident in using the MFT, Though I don't fully understand all of the tests required yet.

*I dont quite understand the Polarity test, Is this simply to test neutral/earth connections are made/secure to all circuits?

I did two years at College - full time and part time to get the electrotechnical and practical knowledge to gain the ability to design, install and test installations - I then spent a further 14 weeks studying for C&G 2391 (Inspection and Testing) - which involved a 2.30hr closed book examination together with a 5 hour practical examination.
So I'm not sure you ever will gain the necessary understanding and more importantly the ability to interpret your results.

Or should I just get a sparky in to check my work and tell me everything's fine ( or not ).

To be honest this is the most sensible thing you have said so far.

 

[brunoo]

I'm confident in using the MFT, Though I don't fully understand all of the tests required yet.

*I dont quite understand the Polarity test, Is this simply to test neutral/earth connections are made/secure to all circuits?

I did two years at College - full time and part time to get the electrotechnical and practical knowledge to gain the ability to design, install and test installations - I then spent a further 14 weeks studying for C&G 2391 (Inspection and Testing) - which involved a 2.30hr closed book examination together with a 5 hour practical examination.
So I'm not sure you ever will gain the necessary understanding and more importantly the ability to interpret your results.

Or should I just get a sparky in to check my work and tell me everything's fine ( or not ).

To be honest this is the most sensible thing you have said so far.

I will go with the latter route.

What's a reasonable price for a sparky to inspect the (ex)shower circuit/secondary CU and all that's associated with that MCB (Not a full inspection, I just want my work inspected.)

Hopefully he'll say its all fine and I've saved a nice wedge on installation costs, Could be wrong though and it's nice to sleep well of an evening

Cheers.