Can anyone explain the purpose of this separate switchfuse and RCD? (Ed.)

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From the pic, I have labelled them 1 and 2

They appear to be isolators and the wires travel to my garage

Could I get confirmation on what they are and why I need two?
 

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The lower one has been added after the wylex fuseboard was installed, presumably because rcd protection was needed for a circuit, but it was felt cheaper to add it on rather than upgrade the whole sub board
 
RCD and main switch fuse for the garage.....

When you turn it off does it turn off lights etc in the garage?
 
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Quite possible both units were installed at the same time - both have a early 90s vibe to them.

Are those two units out in the open, or is there a roof or something protecting them?
 
Since neither enclosure is weatherproof, I presume (hope) that they are indoors?
 
Quite possible both units were installed at the same time - both have a early 90s vibe to them.
I doubt they were both installed at the same time, looking at the shape of the SWA run I'd assume the fusebox was lower down, roughly where the RCD is and the original shape of the SWA was much neater.
Are those two units out in the open, or is there a roof or something protecting them?
Judging by the cobwebs I've estimated this is under cover
 
Not that long ago - well OK maybe long ago to some but during my working life though, RCDs started to become common and were often fitted as a stand alone unit as an addition. So a fuse or a breaker might be proceeded by an RCD in its own housing or the other way around, a fused circuit leaving a swithfuse/consumer unit then enjoyed a RCD on its way to the circuit proper. Eventually it became more common for RCDs to be incorporated as the main switch in a consumer unit.

Before that there were Earth Leakage Circuits Breakers and there was a choice of two main types - voltage operated or current operated, the current operated types were what we now call RCDs and the voltage operated types relied on a connection to "true earth" so could easily become corrupted
 
Do you know what they supply 100%

Turn either off for confirmation
Electricity to my garage

Quite possible both units were installed at the same time - both have a early 90s vibe to them.

Are those two units out in the open, or is there a roof or something protecting them?
No mate.

They are covered and protected from the elements
 
It did used to be quite common to see a plethora of switch fuses/consumer units of all makes and ages in one installation and not a label or chart/diagram in sight.
Lots of guessing and verifying was always the order of the day
 
You don't really tend to see standalone "fuse units" in "customer side" work*. When you see a large** fuse on the "customer side" it's nearly always as part of a unit that also incorporates an isolator, either a single circuit "switch fuse" or a larger "fusebox"/"consumer unit". Even if said isolator is redundant with some other device that could be used for isolation.

Some of those switch-fuses are designed so you can't access the fuse without first turning off the switch. Others, like the wylex unit in your picture just have a warning label.

* The DNO and their predessors do use fuse units without isolators, but they have their own safety rules and supply chains.
** Unswitched FCUs are a thing, but the currents involved there are much lower, so presumablly the risks from someone removing the fuse under load are also correspondingly lower.
 
Hiya Plugawsh,
The term "Switchfuse" was often used to mean a "One Way Consumer Unit" type thingy to put any wylex fuse or breaker in - say adding a shower circuit (and connector block such as Henley or wylex) .
So a 1 way might be called a switchfuse then a 2 way probably called a two way consumer unit and a wylex 604 etc called the consumer unit, so in this example you`d have circuits controlled by 3 (1 + 2 +6) switches and probably loadsa other stuff from different decades too.
and some of those switches were up for OFF and some were down for OFF.
Ho the good old days ;) :cool::LOL:
 
The biggest issue wirh voltage operated ELCBs was that they relied on the CPC of the entire installation being perfectly isolated from earth.
 

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