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Topic Title: 100mA RCD
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Created On: 18 March 2019 08:39 PM
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 18 March 2019 08:39 PM
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Joined: 19 January 2017

Hi, doing an inspection on a 15 year old property that has been fitted with a 100ma RCD main switch on a metal clad Consumer unit (MEM 404ELMNC) on a PME system. Is this is unsuitable and will need to be replaced for a 30mA?
 18 March 2019 09:39 PM
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Probably not needing replacement. Depends on the remit. What is dangerous? Are there any outside sockets?
 18 March 2019 09:59 PM
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Not necessarily - a 100mA as incomer is very sensible if there are many outgoing circuits - but the real question is how are the out bound circuits projected, and do they do anything risky - you can recommend adding 30mA protection to final circuits, but you also need to ask if it is really dangerous, or just not to current standards.

regards Mike
 19 March 2019 07:26 AM
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Assuming the 100mA is non time delayed it is better than no RCD at all.
You might or might not be able to change it to a 30mA RCD .
If you do then it will make it tend to be more compliant.

However it would add the possible problem of one earth fault taking out the whole installation.

Although that is a risk it is sometimes more theoretical than actual.

Example , mine is a front end 30mA RCD and has not given any problems for years, many others (including some on this forum) find likewise.

You you might like to consider keeping as is or time delaying the 100mA and adding 30mA RCDs (or RCBOs if possible) to at least some of the outgoing ways.

What you need to decide at the moment is what codes you are going to award the present set up.

Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

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