Discuss Earth leakage circuit breaker in the UK Electrical Forum area at ElectriciansForums.net
Thanks!The VOELCB pre-dates plastic pipes by a long time!
For rural areas you might not have water mains supply, etc, anyway, it might be brought in by buckets, etc (I kid you not). Even if you did, it is not always going to be low enough to blow a 30A rewirable fuse for a cooker circuit!
I am sure there was, but probably before the 1940s or so.Thanks!
So was there ever an era when no up front device at all protected TT installations?
Or maybe (guessing) an era where earth electrode resistance had to be significantly lower that it needs to be today?
You may be surprised or maybe not, a lot of French properties are still using well water, but now days pumped up to a header tank, no bucket required.The VOELCB pre-dates plastic pipes by a long time!
For rural areas you might not have water mains supply, etc, anyway, it might be brought in by buckets, etc (I kid you not). Even if you did, it is not always going to be low enough to blow a 30A rewirable fuse for a cooker circuit!
They still are in many places!And RCDs used to be known as RCCBs
Right, I qualify for this bitWhile we are quizzing older
Not sure about this bit!and wiser people....
Correct. A TT system without sufficiently low RA to disconnect an OCPD requires an earth leakage device in order to function.Was there a link between ceasing to be able to rely on water pipes as earth electrodes for TT systems and the introduction of VOELCBs?
I was quizzed the other day by a retired physics teacher on the history of TT systems before up-front RCDs and wasn't totally sure of which parts related to which other parts.
Yes. That is correct. That's why I mentioned in brackets(without use of metallic services)I reckon a 1950s property with main earth wire connected to half a mile or so of buried copper water supply pipe, as many around here were, would have had a pretty low RA.
In practice the only countries that tend to use a low RA TT system are those with suitable soil conditions like the Netherlands. They can literally sink a copper wire vertically in to the ground without...This article has some useful info and some handy plots. E.g. the buried horizontal conductor in 100 Ohm.m soil is not reaching 0.7 ohm even at 1km length!
Measurements and Calculations Of Earth Electrode Systems (BS 7430) | EEP
System earthing involves the provision of a connection to the general mass of earth. This connection should have a resistance not greater than that required to operate safety mechanisms to isolate the electricity supply from a fault situation.electrical-engineering-portal.com
Sorry. Misunderstood your reply.I reckon a 1950s property with main earth wire connected to half a mile or so of buried copper water supply pipe, as many around here were, would have had a pretty low RA.
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