3rd RCCB Fault??

[1valiant]

Am I missing something here or is it just plain bad luck? I've recently tested a fuseboard and the RCD failed (MEM A100HE 100AMP 30Ma RCD). Sent off for a new one and it failed got another failed again.
Checked multi-tester on another board, tester works fine. It's on a TN-S system, there's a 16mm earth clamped onto the incoming leading straight to the fusebord, the earth clamp is tight. all bonding is good. Am i missing something or have I just come across a batch of dodgy RCCB's.

Cheers.
Darren.

 

[jks]

Have you checked the insulation resistence,first as it may be leaky

 

[sbelec]

I have a similar problem an rccb A100HE with trip times of 98ms and 40ms, obviously not suitable for current regs and I put it down to age. Have been looking for a replacement and found the following literature:
http://www.neweysonline.co.uk/neweys/pdf/Eaton_Memora_Protective_Devices_&_Accessories_Technical.pdf
Within this booklet from Eaton it lists the A100HE as being 30ma and 40ms but on further reading found this paragraph

30mA​

​

​

​

​

providing a high degree of protection against electric shockdue to direct contact. The device must be able to trip within 40milliseconds when a fault current of 150mA is detected.​

The result is that I believe mine is in its design criteria but that the characteristics of the design criteria and my problem is that the design criteria are not fit for current usage and it is simply not reflected in the simple terminology of the 30ma 40ms that we use today. According to the Eaton website a new unit is available as EAM1002H which is the new designation - interchangeable no idea and will be trying eaton uk later.

 

[sbelec]

Ignore my stupidity, at 1x limit is 200ms and at 5x 40ms as per current on site guide and 415.1.1 in the BGB gives 40ms for 5x but NO time against 1x. But I have never seen one this high, installed a wylex last week and had times of 40ms and 19ms and my house this morning is 37ms and 23ms.
Think the watchword is be aware that current kit is very sensitive whereas older kit wasn't but may still be compliant even if we are not used to seeing the numbers!!! So easy to get led by normal and requirements.

 

[HandySparks]

Welcome to the board sbelec.

Your first post had me worried there. I was just double-checking the numbers in the regs to do a detailed reply when you posted your correction. We all get brain failure from time to time!