Still waiting for the photo but as far as I recall there are what looks to be two RCDs side by side in a modern housing.
From what you say I presume that there is some discrimination.
The whole thing was a relative rat's nest of wires, most of them looking remarkably new.
Cheers
Dave R
I figured, but it was a reasonable place to post something that might help someone ;-)
Alas not necessarily - not all RCBOs are double pole. Some of the older double width ones often were. The newer "slim'n'tall" single way ones are often single pole.
MK refer to their Starbreaker models as "solid neutral" designs. See the description on page 11:
A "modern" 17th edition CU would use two RCDs - then spread the circuits out between them. Posher installs may include a main switch operating a section of non RCD protected ways to allow some additional non RCD ways (or RCBO protected ways). It might be that they have replicated something logically similar with additional CUs. As you say, pictures will help.
Often they way when you need to alter extend something... you may not like the starting point, but its less disruption (and cost) than starting from scratch.
Got me confused there! Starbreaker turns out to be Crabtree, not MK. MK's is Sentry as in the link above. Both are RCD/MCB, although there's no mention of MCB in the Compact Starbreaker:
The single unit with switched Neutral looks good.
With RCBOs, or with RCDs, the requirement to protect all circuits means that the lighting circuits will trip quite easily - as they do at times with just an MCB. Is there any reasonable way to avoid a blowing filament or LED taking out the circuit and still comply with the Regs? Perhaps a delayed overcurrent trip with a 30mS earth-fault trip?
The only ways to do that are
- don't use filaments
- use 12/24v filaments
Why is anyone still using filament lighting? Even chandeliers there are now good LED replacements for.
NT
Yup sorry brain fart!
Yup, there are some about, but you have to read the specs carefully to find them...
Earth faults on lighting circuits are usually rare - so as long as its not sharing a RCD with something else then a RCD style trip is unlikely.
A trip on the MCB part is more likely on a filament lamp failure. You can mitigate that somewhat by fitting Type C curve devices since they permit higher transient surges without tripping.
You can't use a delayed action RCD since that will not offer shock protection. (delayed action RCDs are handy for equipment, infrastructure and fire protection - but not quick enough to prevent injury from shock)
I had cartridge fuses in my old house.
And a right PITA they were.
Instead of that roll of different fuse wires I inherited from my granddad, and hadn't used up, I had to go out and buy one whenever a light bulb popped the fuse.
Hard to find, and stupid prices in the shops too.
Andy
That was by the way of an example. I'm almost all LEDs and have been for a couple of years. Still a few old florries: shed and loft - not worth changing because they do only a few hours a year (the bench lights are LED). Filament: oven, microwave (not much option), fridge (15 years old and still going - not worth an LED).
Just that if I'm in the shed and a lamp goes - apparently LEDs can take out the RCD - I'd rather not be left in darkness because the LEDs go off.
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