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RCD TRIPPING after hoover gets plugged in
- Thread starter Yanni
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I've done global IR tests loads of times.
Put N and L together and test against E.
Sometimes I bob round a pull out plugs and switch off stuff like immersions, boilers, showers UFH etc...
You will get a lower reading, but as long as it's acceptable, it's sweet.
Put N and L together and test against E.
Sometimes I bob round a pull out plugs and switch off stuff like immersions, boilers, showers UFH etc...
You will get a lower reading, but as long as it's acceptable, it's sweet.
You‘re quite right, if two RCDs are connected in series, it‘s impossible to predict which one will trip.
However, in this case the RCDs are in parallel, presumably with the live of one circuit connected to RCD 1 and the neutral to RCD 2. In that case both RCDs should trip. The only likely explanations if only one trips are
1) One RCD is faulty
2) The neutral is connected to a non-RCD bus bar
However, in this case the RCDs are in parallel, presumably with the live of one circuit connected to RCD 1 and the neutral to RCD 2. In that case both RCDs should trip. The only likely explanations if only one trips are
1) One RCD is faulty
2) The neutral is connected to a non-RCD bus bar
It remains a race, even in 'parallel'. The first to respond, removes the reason to trip, the fractionally slower unit remains engaged/untripped. No two electro-mechanical items, will ever behave exactly the same, respond in precisely the same way.
The video proves nothing. The OP is there at the CU, resetting a single ,tripped RCD. Try unpluging the vac, reset both RCD's, then plug the vac in.
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But both rcds trip in the video
No, they are in series, in the sense that current flows from the supply, through the live side of one RCD, through the load, through the neutral side of the other RCD, and back to the supply.
I see what you mean but I am not sure that one wire in the wrong place with all the other wires correct means the RCDs are in series.
This is definitely in parallel:
This is definitely in parallel:
True, but the load is in series with both RCD's, until one of the RCD's trips.
Y - e - s - - - - but the RCDs are not in series. Is there a more accurate term for that.
That sounds logical but are there any numbers for the situation.
If both RCDs have experienced the same fault but one has not tripped does that not mean it is unsatisfactory.
Are there time factors for the duration of a fault which should cause an RCD to trip - or does it just need to recognise a residual current for a very short time and then continue with its tripping process?
According to the OP's test certificate one of the RCDs trips in 22.3ms and the other in 33.5ms so what happens in the 11.2ms after the fault has been cleared that still causes the second RCD to trip?
I'm sure you are already aware of the answer to that question.
Of course not, it simply implies that one, is marginally quicker to react than the other - the test figures confirm that, if they are accurate, and repeatable.
No, what are they?
If I were, I would not need to ask, would I?
But both RCDs tripped in this example despite one tripping 11.2ms after the other had presumably cleared the fault.
Its tripping or to be more precise its in to process of tripping once that process starts ie is over the 30mA required then its not stopping, the variation is down to the manufacturing tolerance of the RCD trigger, ie the solenoid and components, after all its near instant disconnection not instant.
If we were doing this in a clean environment, good annealed copper, ie no electronics then a wave front would travel @ 60 Hz @ more or less 3.2 m/s and as 11.2ms is a small number, in good copper that time equates to 3.52cm distance so the wave front will reach the second RCD slighty behind the first ...so regardless if even both rcd's took exactly the same duration to trip one would always lag behind the other, because by the time the first RCD had tripped the wave would be passed the first RCD on on its way to the second.
Its a fairly common problem in physics, we state something and then the qualifications to that rule are forgotten, ie the speed of light.. people always miss in a vacuum bit or water boils at 100c... at 1 atmosphere of pressure.
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