Blimey. I'll concede that. They have devloped since my time...BUT if you look at the circuit diagram later in that video, you will see than no earth is involved. The only possible thing it *might* do is nothing to do with RCD detection per se, but it MIGHT detect voltage on the neutral with respect to earth.
Not something that bothers me at all.
Imagine what AFDDs are going to be like, a DSP to discriminate between harmless sparks and fiery sparks?
Yes, the reference circuit for the chip shows it has a "substrate ground"
but no PE or FE earth connection, makes you wonder if MK have added something extra on the PCB for lost-neutral detection?
makes sense, and the IC uses a SCR to "crowbar" live to neutral if it detects an imbalance fault, it won't draw current for very long over the thin white wire ...
Probably worth highlighting the reason for Adam's indignation regarding over sleeving. While the correct colour sleeving for a protective conductor is the normal green/yellow, the correct colour for a functional earth is actually cream.
Although the printing on that RCBO actually says 'PE' instead of 'FE' for the white flylead.
and the text within the little box connected to the current transformer and the earth flylead says "1?" instead of the expected "I?"
Original image URL (will be zoomable unless you have a portrait monitor).
Note that MK Sentry range is now licenced for CircPro to manufacture/sell rather than being a Honeywell brand.
Its not.
No, and it does not need to either.
Not true of a functional earth - you are thinking of a protective earth.
When you make the earth connection between your turntable and amp, is that for safety?
Its not a protective earth, so won't ever pass a significant current even under fault conditions.
You can if you have a functional earth, that is one of the reasons for having it[1].
Even in even in the event of a PEN conductor disconnection on a TN-C-S supply, that functional earth should still have *some* fortuitous earthing via the main equipotential bonds etc. That will allow adequate current to be drawn by the electronics in the RCBO to detect the fault, and trip.
[1] One might argue the benefits, since the loss of neutral is rare, and adding an extra connection makes the job of wiring more time consuming and also makes testing more complicated since the FE will likely need to be disconnected for IR and earth loop testing. However others would cite that reports of loss of neutral still occur about once a day somewhere in the UK.
There is no actual requirement for a RCBO to have a FE connection (and indeed many brands don't), however if its present, then the standards do have things to say about how it should work IIUC.
I couldn't see any mention of PE or FE in BS EN 61009-1, other than in deleted wording.
The 2004 version has a requirement to use label the terminal with the protective earth icon as per IEC 60417-5019a rather than the functional earth symbol as previously recommended!
Can't recall where I did see mention of it now.
Do RCBO's still consume power even when no user devices are using power ?. Assuming 6 in the consumer unit of a typical average house, how much leccy is used per year ?.
Yes
The chip used on the PCB says max 10mA consumption, so that's a couple of watts per RCBO, I doubt anything else on the PCB consumes much unless it's in the act of tripping, so one or two quid each per year?
Yup that have "always on" electronics - so will consume a very small amount same as any RCD.
(The MCB element will also dissipate a certain amount of heat when on high load since this is a function of how the thermal part of its trip mechanism works)
Finding data for the power consumption or the RCD elements themselves is actually quite tricky. ISTR Wylex publishing a figure of between 1.5 and
2.5W per RCBO depending on load.So if we said it was 10W total for your 6 circuit CU, that would be 1kWh every 100h operation, or ~87 kWh - could be £10 or so depending on your unit price.
MK pulled out of the CU market last year. It was posted on here. Probably just before we went to the Elex show.
But the MK sentry brand is now back ... licenced by Honeywell to CircPro, who apparently are the people who were making the sentry range all along!
I wonder who is making the SPDs?
strangely they seem to be black rather than pale grey.
these look quite similar, not identical though
Is this "functional earth" in the sense of reducing interference (like AV interference)?
Yes, basically any earth that is not just there to carry a fault current.
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