Whilst doing a maitenance check

[Rather be Fishing]

Good morning guys I hope your all well. Since I got the first part of my 2391 done I've been having a rest from the studying because it was at points a little bit intense doing mock after mock after mock.

Ill will soon be picking up where I left off and I will be indulging (at cost no doubt!) in some practical testing workshops to get my testing skills up and then I'll need to get back to the studying as I'll have a written exam to do along side it as well.

Currently though ive got and issue at work.

I don't think it's a particularly big job but this is where I will show my limited knowledge/experience with the question or questions that follow but I guess that's what this forum is for and why I was kindly let on.

So I was testing some Rcd's to make sure they function correctly and I had one that that didn't trip the mechanism when I pressed the test button so there for I'm going to need to replace it.

I've added some pictures to show you what it is I'm looking at and I will do another post to tell you what my plan is in regards to attacking it and getting it sorted out.

My main concern is not killing myself or blowing anything up

I'm just about to go and do a generator run but will post my plan of attack after that.

Cheers

?

 

[telectrix]

looks pretty simple. isolate and prove dead with the correct isolator above the trunking. once proven, lock off isolator. then replace RCD.

 

[snowhead]

Just to note, those Wylex RCDs have been obsolete for years, you'll have to get a new RCD and enclosure and change the lot.

 

[telectrix]

before going down that route, it could be that the RCD was just sticking from lack of testing/operation. try doing a "proper" test on it and if times are good, try the button again.

 

[Rather be Fishing]

looks pretty simple. isolate and prove dead with the correct isolator above the trunking. once proven, lock off isolator. then replace RCD.

Cheers te

looks pretty simple. isolate and prove dead with the correct isolator above the trunking. once proven, lock off isolator. then replace RCD.

Cheers @telectrix

I just went in to have a look at the RCD in question and I isolated it with the isolator above which was conveniently labelled up correctly for a change.

I proved it was dead by testing the supply side of the Rcd.

I will order a new one and look foward to replacing it. It is certainly a bigger ubit then the ones I've seen in domestic properties.

One thing that is weirding me out is

There is a random blue cable that has been taped off at the end of itinside the housing for the rcd.

I'm presuming it's a neutral as it's blue in colour but I cannot be sure of that and it might be actually something else.

It's hard to see from the pictures but where the red and black supply cables go in at the top of the Rcd .

Red goes to the terminal labelled 1 and black goes to the terminal labelled N.

There are 2 other terminals available that are not in use and although hard to see at the top of the rcd that are labelled 2 and 3.

Is this because it can be used as both a 3 phase rcd or as a single phase rcd as it is currently doing so.

 

[Rather be Fishing]

before going down that route, it could be that the RCD was just sticking from lack of testing/operation. try doing a "proper" test on it and if times are good, try the button again.

I haven't got a tester on me but I know that there is one at the company so I will try and get my hands on it and armed with my onsite guide and gn3 will have a go at testing the RCD as I'll need to look at that to double check I am doing it write.

I will deffo do this and test the rcd test button after but at the moment you press it and nothing happens it doesn't trip itself out.

 

[telectrix]

think it may be a 3 phase unit. see the 415/240V , top left.

 

[Rather be Fishing]

Just to note, those Wylex RCDs have been obsolete for years, you'll have to get a new RCD and enclosure and change the lot.

Cheers for the heads up @snowhead much appreciated mate.

At least I know that if I can't get the button to work after testing it properly I'll have to install a compleley different housing and Rcd which will still probably go ok but not a simple as hooking one out and slipping one back in.

 

[UNG]

There is a random blue cable that has been taped off at the end of itinside the housing for the rcd.

I'm presuming it's a neutral as it's blue in colour but I cannot be sure of that and it might be actually something else.

It's hard to see from the pictures but where the red and black supply cables go in at the top of the Rcd .

Red goes to the terminal labelled 1 and black goes to the terminal labelled N.

It looks like the outgoing cable is a 4 core SWA with the blue unused, the yellow core being used for the earth looks like it needs some green / yellow sleeving or tape on it alternatively if you have some green paint you could just paint a green line down the yellow core

 

[telectrix]

pity the thing is yellow and not green. we could get local council to stripe it in yellow. they've run out of road here fot their yellow lines and have a surfeit of yellow paint.

 

[westward10]

Those rcds for single phase use had linking bars across the two left and two right terminals. I am not 100% certain whether it affects operation if they are missing, probably not but it may be the reason the test button does not function.

 

[snowhead]

I remember now, As Westwood, the test button only works on 1 phase, so the Live needs to be in the correct terminal.
Live needs to be in termnal 3 next to Neutral, should be a drawing on the side.

 

[westward10]

There used to be two shaped and plated linking bars.

 

[Rather be Fishing]

Cheers for all the advice guys it's bloody amazing of you.

When I am next there I will put the live from terminal 1 into terminal 3 and see if that makes the test function in the rcd work.

Failing that I will try to properly test it like @telectrix suggested

And if all that fails I will put in a new housing and unit

 

[Rather be Fishing]

I remember now, As Westwood, the test button only works on 1 phase, so the Live needs to be in the correct terminal.
Live needs to be in termnal 3 next to Neutral, should be a drawing on the side.

@snowhead thank you for you help and suggestion.

I am a bit confused though.

How do you no that the supply live needs to come out of terminal 1 and be put into terminal 3.

Is it just experience and general knowledge on your part.

I will have a look on the side of the Rcd the next time I am there just to see if there is a diagram.

Silly question but why does the test button not function with the supply live in terminal 1but it might if it's in terminal 3.

Just trying to follow along with you guys