Discuss 18th edition exam question.. in the UK Electrical Forum area at ElectriciansForums.net
Sounds about right to me.There's me thinking an RCBO protects against over-current and earth fault current?
I think it's a genuine exam question, one of perhaps a few which the 'experts' have wrong. I can remember a similar situation with the 17th exam, where I stated the obvious answer but it was 'wrong' apparently. Even the course tutor agreed. However, this time I've skipped the course and just booked the exam so I have no tutor to back me upSounds about right to me.
I think it’s just a poorly worded example question and for what it’s worth, I would’ve picked your answer too
From the BBB: "A residual current operated switching device designed to perform the functions of protection against overload and/or short circuit"It does, and IMHO it's a really bad question. I remember that one from my exam and I'm now fairly sure I got it wrong!
I don't have BBB here at home but in the definitions section at the beginning does it have "earth fault current" listed?
It might be that "earth fault current" is more associated with "prospective earth fault current" in the regs, and answer one isn't technically using correct terminology in the mind of whoever wrote the question, in which case answer 4 is the closest.
But it's a definitely a poor question!
From the BBB: "A residual current operated switching device designed to perform the functions of protection against overload and/or short circuit"
So it doesn't protect against earth fault currents??
(Tangent, but the question I got hung up on in exam related to:
463.1.2
"A single-pole switching device shall not be placed in the neutral conductor except for the connection of the control device for lighting circuits as shown in Fig 46.1"
The question was basically " when can you switch the neutral conductor in a lighting circuit" and I was sitting there thinking "never?!"
)
Basically a contactor/relay, because the switching circuit that energises the coil is not connected to the lighting itself, so switching the N of the coil doesn’t leave the lights live. Never used that fact since!I'd think the same. But I still can't work out what a 'single pole switching device' (switching neutral only) for control of lighting circuits actually is?
Reply to 18th edition exam question.. in the UK Electrical Forum area at ElectriciansForums.net
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