Blowing sockets and popping RCD

[Josh555]

A client asked me to add two sockets in their bedroom

I took power from two sockets in the lounge which is behind the bedroom wall.

I ran a cable out of each socket for the new socket

The problem is it now is tripping the RCD and blowing the old Existing sockets and light switches

But the new sockets I added still work fine

The old existing sockets and switche are blown and unusable

When I try to reset the RCD It pops and Sparks down

Any idea to why this is happending

 

[Lucien Nunes]

The problem was a debris in the terminals of the old sockets. a lot of plaster dust from the plasterer as they were doing the place up

That's surprising and I think there might be more to it than plaster dust itself. Dry / dusty plaster is a reasonable insulator. Wet plaster is conductive but one would have to form a bridge of wet plaster from the line terminal to the earth to get enough leakage to trip an RCD.

What were the IR readings before / after corrective action?

 

[Josh555]

That's surprising and I think there might be more to it than plaster dust itself. Dry / dusty plaster is a reasonable insulator. Wet plaster is conductive but one would have to form a bridge of wet plaster from the line terminal to the earth to get enough leakage to trip an RCD.

What were the IR readings before / after corrective action?

Results were the same before and after
L-N >999
N-E >999
L-E >999

 

[timhoward]

Fare enough just not used to testing before carrying out work. Will think about this moving forward

It's good to hear you say that. If you start making this a habit then it will definitely save you a heap of hassle one day. As well as being required by regs (as @Lister1987 explained) checking things are fine while you still have the walk-away option is a fundamental self-preservation tactic!

By the way, I'm sure several of us could think back to our first post on here and shudder slightly! It's worth sticking around. There's lot's of great people lurking around willing to help.

 

[Josh555]

It's good to hear you say that. If you start making this a habit then it will definitely save you a heap of hassle one day. As well as being required by regs (as @Lister1987 explained) checking things are fine while you still have the walk-away option is a fundamental self-preservation tactic!

By the way, I'm sure several of us could think back to our first post on here and shudder slightly! It's worth sticking around. There's lot's of great people lurking around willing to help.

Definitely

 

[James]

By the way, I'm sure several of us could think back to our first post on here and shudder slightly! It's worth sticking around. There's lot's of great people lurking around willing to help.

I am sure if we are being honest, most of us will have a little shudder thinking back on some of the first jobs we did on site.

 

[ipf]

I am sure if we are being honest, most of us will have a little shudder thinking back on some of the first jobs we did on site.

I remember an under manager at our first wholesalers causing great amusement by taking me apart as an apprentice with a list of materials to pick up. I let it rest for a few years before ripping him apart on numerous occasions when materials I wanted weren't immediately at hand, faulty or just crap.
Standing joke, for a good while, how he used to make himself scarce before I got to his office.
Give him his due, though, he was always one of the first to offer me drinks when we went on various free do's.
He ended up very high up the supply chain and a very useful contact in the trade. They don't seem make 'em like that, these days.

 

[Pegasus]

It's good to hear you say that. If you start making this a habit then it will definitely save you a heap of hassle one day. As well as being required by regs (as @Lister1987 explained) checking things are fine while you still have the walk-away option is a fundamental self-preservation tactic!

By the way, I'm sure several of us could think back to our first post on here and shudder slightly! It's worth sticking around. There's lot's of great people lurking around willing to help.

I just started out in the electrical field and this thread has definitely taught me a lot.. never considered that testing had to be done before making alterations but it makes sense. Becoming good at testing will definitely prove useful in the long run.

 

[mainline]

No they were not reversed I checked my connections like I said. I also used my socket tester before I left which shows if all cables are in the correct terminals

I doubt your socket tester will see N - E reversal.

It could also in the right circumstances account for a light when switched on to trip a rcd.

 

[Josh555]

.

 

[mainline]

Damn this is getting interesting, I'm waiting for his continuity, IR, Zs and RCD readings using the new x1 AC test now amendment 2 has been published. I also can't wait to find out if the 'client' gets his minor works cert. More importantly, did it get fixed and what the problem was

I didn't know that there is a new x1 AC RCD test ? How does that work compared to the old one ?.

 

[timhoward]

I didn't know that there is a new x1 AC RCD test ? How does that work compared to the old one ?.

In short, just omit the x5 tests.
I still test at x 1/2 for both waveforms as I want to know it’s not overly sensitive and then the required x1 on both waveforms.

Now Auto mode is less useful i tend to test all of them at 1/2 and then all of them at x1 to avoid fiddling with the tester too much.

 

[goasis]

In short, just omit the x5 tests.
I still test at x 1/2 for both waveforms as I want to know it’s not overly sensitive and then the required x1 on both waveforms.

Now Auto mode is less useful i tend to test all of them at 1/2 and then all of them at x1 to avoid fiddling with the tester too much.

I think it's still a requirement to ensure they dont trip at 50%

 

[Lister1987]

In short, just omit the x5 tests.
I still test at x 1/2 for both waveforms as I want to know it’s not overly sensitive and then the required x1 on both waveforms.

Now Auto mode is less useful i tend to test all of them at 1/2 and then all of them at x1 to avoid fiddling with the tester too much.

Worth remembering that 7671 is a minimum, if you want to carry on using auto and doing 0.5x 1x 5x and Ramp then there is nothing stopping you.

The cynic will say that the 'new' testing regime may be "better" but then we remember that OEMs are on JPEL64 and would favour the reduced testing as it would result in fewer returns

 

[timhoward]

Worth remembering that 7671 is a minimum, if you want to carry on using auto and doing 0.5x 1x 5x and Ramp then there is nothing stopping you.

Agreed, and circumstances dictate what's worth doing.
Ramp tests are certainly useful for lots of situations.
But even under the old regime if a modern RCBO tripped at under 40ms on the x1 test then increasing the current for a x5 test is never going to slow it down and IMHO it was a pretty pointless test in a lot of cases.