Am I being a snob, or is this actually dangerous

[Inteificio]

On a distribution board last week in a farm house, I saw 2 core 4mm SWA with the sheath terminated by having a couple of strands in a terminal block.

A photo would save a thousand words, but I found out on that day that my camera phone is not waterproof =-(

The other sparky on site said it is fine if the Zs is in, which I accepted at the time.

Then I got thinking, the Zs will make sure the fuse trips, but how can you guarantee conductor safety while the fuse is tripping?
We had a similar issue in our factory where a spark proved that a distribution circuit would blow in 4s, within the limit. However I pointed out the wires would be melting the insulation after 1s.

I can do the calcs to prove how hot that conductor will get, but that is not sparky level maths and I know the guy who installed it won't be able to do that.

So my question is:

When is it ever safe to terminate only a couple of strands of the armouring on SWA when it is being used as the CPC.

This is quite important as I am going to be politely confronting the guy, and I don't want to risk causing offence if I am wrong. I will be the first to admit domestic is not my speciality.

 

[Inteificio]

Just out of curiosity,how come he ended up on the job of wiring your parents house?

Think either the architect or main contractor put him there.

 

[Sparky_Ben]

basically, if this so called electrician was working on any of my families houses i personally wouldnt allow him to enter back on site, he is a total cow boy and should have the book thrown at him

 

[GLENNSPARK]

would be interesting as to how he managed to blag his way into the job in the first place..lol....

 

[Inteificio]

would be interesting as to how he managed to blag his way into the job in the first place..lol....

I have no idea what he has done, or what still needs doing, so if I threw him off now I would not know where to start.

When he has finished the board will be labelled and the test certs will be there (or I will take his head).

 

[Sparky_Ben]

i would rather have the headache of finding out what has been done and what hasnt than let this man touch another cable

 

[Des 56]

I am saying the mathematics required to precisely calculate the increase of temperature for those two strands is not covered under any electrical course that I am aware of.
do not take this as a slight on electricians, I just meant it is not covered in any of the electrical courses I have taken.
Does not mean that any individual sparky cannot work this out!

The only individual sparky I was referring to was the protagonist of our tale.
If he cannot calculate the current usage of a lighting transformer, it seems a safe assumption that he could not do this far more complicated process.

Was that what you were asking?

Thanks for your response,it seems we do,as electricians, take these factors into account
eg Thermal overload

Thermal overload protection calculates the temperature of the conductor based on specific conductor data and the current present in the circuit,
and is used to protect conductors from damage due to extended overloads.

 

[Engineer54]

I am also not sure on what it is protected by. There is confusion on one of the two row boards. The main incomer feeds an RCD protecting the bottom row, but seems to be no RCD on the top.

I am under the impression that as on TT everything, without exception, needs to be RCD, I am really not sure on that though, so if someone can confirm that would be appreciated.

So this is either protected by a 30ma RCD or B MCB on TT.

Seems that your getting a front end RCD protected CU, which ain't the most sensible thing to do on a TT system. Fine if it's an S type 100mA and the rest of the CU is made up of 30mA RCBO's, but somehow with this particular sparks, that is just going to be ''Wishful Thinking''!! lol!! Remember, your parents will be relying on any RCD protection afforded to this installation for earth fault protection, as it's extremely unlikely that your TT system will be up to the job!!!

What i can't make out, you keep talking about waiting till he's finished?? Surely that means destroying other trades finished work?? Then you even say that you will go in and fix this and that!!!! I can see No point whatsoever in waiting until it's finished, ....get these and any other snags that you have found sorted now, with the minimum disturbance to finishes etc...

 

[GLENNSPARK]

Seems that your getting a front end RCD protected CU, which ain't the most sensible thing to do on a TT system. Fine if it's an S type 100mA and the rest of the CU is made up of 30mA RCBO's, but somehow with this particular sparks, that is just going to be ''Wishful Thinking''!! lol!! Remember, your parents will be relying on any RCD protection afforded to this installation for earth fault protection, as it's extremely unlikely that your TT system will be up to the job!!!

What i can't make out, you keep talking about waiting till he's finished?? Surely that means destroying other trades finished work?? Then you even say that you will go in and fix this and that!!!! I can see No point whatsoever in waiting until it's finished, ....get these and any other snags that you have found sorted now, with the minimum disturbance to finishes etc...

aye and get this turnip head out the door n all....

 

[baldsparkies]

Tell the guy where to go and why.
Then sort it out. If thats the way you want to go, then go that way.
In the time it takes to enter multiple replies to this thread. You can have the job sorted.
And your calcs will hold true within the practicalities of the installation, helping you to sleep content at night.

 

[Knobhead]

I’m sorry Inteificio but this thread has got totally out of hand.
Three days and you haven’t done anything to rectify what is obviously a dangerous situation. What have you done exactly? Other than spend time on the net.

 

[Inteificio]

I’m sorry Inteificio but this thread has got totally out of hand.
Three days and you haven’t done anything to rectify what is obviously a dangerous situation. What have you done exactly? Other than spend time on the net.

Gone mountain biking.

I can't get back there for weeks, so have given a long explanation to dad to make sure the dangerous point get fixed asap.

 

[Inteificio]

Thanks for your response,it seems we do,as electricians, take these factors into account
eg Thermal overload

Thermal overload protection calculates the temperature of the conductor based on specific conductor data and the current present in the circuit,
and is used to protect conductors from damage due to extended overloads.

I was under the impression the formula in the red book only cover continuous conductor size, the effective conductor size drops for a few cm at the point where only two wires are part of the circuit.
The calcs of this two cm section of wire are more difficult. Not horrendously more difficult, but I would put money on the fact that if I set this problem to my team not everyone would be able to do it.

 

[Paul.M]

Here's 3 regs you can throw at him:- 522.8.5, 526.1 & 526.6 or just tell him to read section 526 lol. I'm not going to get into the debate about regs being none statutory but these are the regs that would be used to prosecute in a court of law.

 

[Engineer54]

Gone mountain biking.

I can't get back there for weeks, so have given a long explanation to dad to make sure the dangerous point get fixed asap.

There's something about this guy that just doesn't ring true, or indeed add up!!!

 

[Knobhead]

There's something about this guy that just doesn't ring true, or indeed add up!!!

Precisely why I asked the question.