350ma test for type A rcds

[7029 dave]

You set your tester to 30mA and test it.

Thats what I do lol, good to see you back and on form Dave.

 

[davesparks]

Thats what I do lol, good to see you back and on form Dave.

Well it seemed like the obvious answer

 

[Markyd]

It's only 1x on any form of testing, EICR or initial I believe. The 5x are additional optional tests according to GN3, for troubleshooting or diagnosis purposes only, not for routine testing and specifically not for compliance with BS7671.

Correct....just checked and my certs have not been upgraded to amendment 2

 

[pc1966]

Yes, note 6.

Since RCDs are only rated for a finite number of operations, carrying out frequent​

optional tests can shorten the product’s life. For example, in carrying out all of the above tests, including optional tests, for a 30 mA Type B RCD, would require the RCD to trip 12 times.​

I would be very surprised if MFT testing had any real impact on RCD life.

I can see they probably are only going to last a dozen or so high-current disconnections so repeatedly closing them on to a fault situation and hoping it stays on is not a good idea!

 

[sinewove]

You are confusing units I think?

Sorry thought they were tested at 350ma?

You set your tester to 30mA and test it.

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

 

[nicebutdim]

Sorry thought they were tested at 350ma?

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

Why would age be a factor? 30mA is 30mA, just as it was 100 years ago.

Are they 30mA or 300mA RCDs?

What is their part number?

What trip current is indicated on the front? Perhaps 0.3A

 

[timhoward]

Sorry thought they were tested at 350ma?

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

This could easily get confusing....

Before amendment 2 they were tested at X 1/2, X1 and X5
So a 30ma RCD would be tested at 15ma, 30ma and 150ma.
They were also tested on a rising and falling wave pattern (0 degrees and 180 degrees)
The pass results were no trip at 1/2, 300ms at x1 and 40ms at x5

(I had assumed you were talking about 350ms, hence my units comment, but let's forget that.)

Since amendment 2 the minimum testing is reduced to testing at x1, so just 30ma.

Now your 2nd comment about brand new Hager Type A's not tripping until you give them 300ma is interesting.
It would be exceptional for 9 to all fail by such a margin, so I can only conclude the tester is setup wrong, the tester is faulty, there is something strange with the installation or (respectfully) you are making a mistake somehow.

A barrage of questions follow.....!
Is the main earth at the CU connected?
What exact tester are you using?
What does the RCBO say on it for I delta N, post a photo if you have one.
Are you setting it to type AC?
Have you tried testing at the output terminals with no load?
Have you already done IR testing and did you do it with the RCBO's in situ?

You can nearly detect 300ms without a tester; when you press the test button do you get an instant snappy trip or a trip after about 1/3 second.

I'll stop now....and hope someone can figure this one out!

 

[pc1966]

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?

Any 2nd opinion with someone else's MFT to rule out a test fault?

 

[Electro-tech]

This video may be useful or relevant if you prefer to do all tests. The Megger MFT feature, not sure of other testers.

 

[davesparks]

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

So they failed the test? What did you do next?

I would have been double checking everything to make sure I hadn't made a mistake at that point.