Really? I'm interested in your thinking? Do you fit the second rod because the first reading was too high or just your standard practice. I had considered doing this but depending on the Ze measurement alone. I'm going back to a couple of properties in the summer to test again - my measurements...
I believe we should consider a big difference between a lightning strike and over voltage, since they are not the same. An SPD is for over voltage and will not protect against a direct strike or one very close by. I recently attended a course for SPD’s and have an interest on TT (there are many...
Practitioner's Guide to Temporary Power Systems - IET Electrical - https://electrical-shop.------.org/books/electricians-guides/prac-guide-temp-power.cfm
The author James Eade has published a lot of articles one recently on Earthing
There's a niche market for temporary power supplies - if you fancy doing that sort of thing - festivals, TV, concerts, exhibitions etc. Most of the kit comes from contractors - pre-tested. Can send a link to an interesting podcast that NAPIT ran recently.
This whole thread made me chuckle - very funny toward the end. It is a tough subject and appears to be very experience oriented. I would advise the OP to get one, some conduit and play around.
The only time I've needed to fit a type C was for a welding machine, pretty inductive loads can look like a momentary short on start up and cause it to trip. This was dedicated 16A supply, be wary that the max Zs values change (almost a half lower) for the whole circuit - from 2.73 to 1.37 Ohms...
@spinlondon Agree absolutely. I just wanted a way to prove it - with a measurement. With more and more electronics being used on domestic circuits, I believe this will become important, since an AC or indeed A type RCD may not be protecting them but passing the tests. Don't get me wrong here...
This is my point of interest:
http://www.doepke.co.uk/download/Techpub-17
"Type A RCDs are not suitable for detecting smooth DC residual currents since they result in pre-magnetization of the summation current transformer and therefore significantly impair functionality. Based on the relevant...
Good answer - you understand exactly. There is no way of knowing and your 'playing safe' is my view too. It would be nice to be able to know and prove it. I'm not concerned that the DC would trip the AC type - I'm interested to see whether the DC leakage would flood the AC coil and prevent it...
Thanks @spinlondon Exactly - that’s where we are but the dc leakage will come from usage, so if during the test equipment is off, say people are out it’ll pass. Was thinking of a test extension lead with the earth looped out for the clamp and monitor DC leakage on equipment. I’m trying to verify...
I have a pack of the white ones - only used them to fix a stair bannister to a wall (the brackets were white) worked a treat but I do recall having the same issue.
I’m the in the same boat, I thought it did but haven’t read anything more - market appears to be for overtripping AC leakage but I’m interested in seeing whether the loads connected have DC leakage that could prevent the AC type operating. It may well pass the RCD testing but when the family is...
So, I already have a cheap clamp meter. The exam question here is how can I prove that a type AC RCD will be rendered useless by the DC leakage current - I could be reading AC leakage which is fine. How can I possibly recommend a A type if I cannot measure the 6mA DC threshold leakage current.
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