RCD Test button wont trip

[themoosdad]

I have just changed an old Wylex consumer unit for a new Excel 6 way with an already installed RCD in it.

When i press the Test button the RCD wont trip out.

I have disconnected all circuits and it still doesnt work.
I have reconnected just one circuit (water cylinder immersion) turned the immersion on and it still doesent work.
I disconnected the Immersion circuit and connected just the shower circuit, turned the shower on and it still doesnt trip out.
I have also swapped out the RCD for another (seperate consumer unit for economy 7 storage heating) and repeated the above steps and got the same results.

Should the test button trip out the RCD with no circuits connected?
I would assume that a 9.5Kw Shower would be a sufficient load if current needed to run through the RCD for it to trip?
Any ideas would be greatly appreciaated.

Im not an electrician but am fairly competant. I dont have any sophisticated test equipment other than a multimeter.

Many thanks.

 

[Spark123]

An RCD should trip with no load on it when the test button is pressed.
It should also be tested using proper test gear to ensure it is within spec.
I take it you know about part p.

 

[Scoby_Beasley]

An RCD should trip with no load on it when the test button is pressed.

But it does need power. Is the main switch on?

 

[themoosdad]

Yes the main switch is on.

 

[Spark123]

If it has 230v across the two poles on it then it is duff, so is the other one.
Not sure on Excel as a make, possible re-badged Chint??

 

[themoosdad]

Yes i have got 240v across it.

Is it usual that 2 new RCDs could both be deffective?

Any way of testing them with a multimeter or only with an RCD tester?

 

[Spark123]

It is possible that they are both defective yes.
There is no way to check an RCD properly with a normal multimeter, even if the RCD is working correctly. You need to use a proper RCD tester.

 

[Chri5]

Go on send us a picture of the cu so we can see where the rcd tails and in side main incoming side are wired.

 

[JohnW2]

There is no way to check an RCD properly with a normal multimeter, even if the RCD is working correctly. You need to use a proper RCD tester.

True, but if the OP is sure that power is getting to it's input terminals, then, if it doesn't respond to the test button, it does not need proper testing - since we would already know that it's duff!

Kind Regards, John

 

[themoosdad]

Not at site at the moment to take a photo.

RCD was pre installed and wired into CU when purchased.

Incoming tails are fitted correctly.

 

[ricicle]

I suggest you stop fitting consumer units until you can understand how RCDs work and how the test button operates !

 

[themoosdad]

Have read plenty of info on how an RCD works and the test button operates. I asked if it could be tested with a multimeter. You dont have to be qualified in a certain field to understand things.
I would suggest you dont try to talk down to people

 

[HERTS P&D]

No one is talking down to you.

IT'S FOR YOUR OWN SAFETY!!! and the home owner.

Andy

 

[JohnW2]

Have read plenty of info on how an RCD works and the test button operates. I asked if it could be tested with a multimeter. You dont have to be qualified in a certain field to understand things.

Very true (I'm not a qualified electrician). However, as I said above, if one understands RCDs, one knows that if they are properly powered and the test button does not result in them tripping, then they need replacing - there's no point in trying to 'test' them any further, either with a multimeter (which can't be done) or with more sophisticated equipment.

I would suggest you dont try to talk down to people

I agree that it was a rather abrupt comment, but I am afraid that, IMO, the spirit is correct. Although whether or not one has 'qualifications' is, per se, neither here nor there, replacing a CU is a major job which requires appreciable understanding (and test equipment) if it is to be done properly/safely (which is one of the reasons why one has to notify such work, if 'DIYed', to the Local Authority). The fact that you are asking these questions, and admit that you don't have the necessary test equipment, suggests that it is probably not really something you should have been doing. However, since you clearly have done it, I personally am inclined to take the pragmatic view that we ought to try to help you 'sort it' (some would tell you to just get an electrician to sort it out for you) - even if that approach usually gets me a lot of criticism and flak from some of those here!

Back to the issue - it does seem pretty unlucky that you should have two faulty RCDs but, if you are absolutely sure that power is getting to the input terminals of the RCD, then failure to respond to the test button means that they are defective and need replacing.

Kind Regards, John

 

[themoosdad]

I am the home owner and safety is paramount otherwise i would have left the old CU in place.

The installation will be inspected and tested by a certified person once completed.

Thanks to those that have given useful advice