Cable entry into Consumer unit

[Taylortwocities]

I’ve seen some garage CU’s that only have an RCD (and some MCB’s). There’s no main switch.
In that situation, the RCD is ostensibly the main switch?

If it disconnects the line and neutral of the incoming supply then it is the main switch for the garage circuits.

 

[JohnW2]

but it's not an RCBO.

True - but to clarify (for Jupiter and others), although RCCBs and RCBOs are both "Residual Current Devices", and presumably because the former were around for many years before the latter appeared, 'common (almost universal) usage' of the terminology refers to RCCBs as "RCDs" (since for many years they were the only type of RCDs around), and refers to RCBOs as "RCBOs".

Hence, unless they were deliberately trying to confuse, I don't think anyone would usually refer to an RCBO as an "RCD", even though that is strictly correct (since RCBOs are "Residual Current Devices")

Kind Regards, John

 

[Jupiter01]

If it disconnects the line and neutral of the incoming supply then it is the main switch for the garage circuits.

Can I check if that's what Garage CU do? I thought they did...
Here's an example of the sort of thing I was thinking of:

MK Sentry 4-Module 2-Way Populated Garage Consumer Unit

Order online at Screwfix.com. Fully populated metal enclosure that complies with a top hinged door to ensure the door is closed when the unit is not in use. Pre-fitted with all of the necessary devices. FREE next day delivery available, free collection in 5 minutes.

www.screwfix.com

 

[JohnW2]

If it disconnects the line and neutral of the incoming supply then it is the main switch for the garage circuits.

It is - and, for that reason, I think that all RCDs (RCCBs!) are designed to have adequate contact separation when open (etc.) fair them to qualify as devices acceptable for isolation, per BS7671.

Kind Regards, John

 

[JohnW2]

Can I check if that's what Garage CU do? I thought they did...

As TTC said, yes. Some people call the device at the upstream end of a CU the "Incomer", whether it is just a 'Main Switch' or an RCD (RCCB, incorporating DP switching).

Kind Regards, John

 

[EFLImpudence]

True - but to clarify (for Jupiter and others), although RCCBs and RCBOs are both "Residual Current Devices", and presumably because the former were around for many years before the latter appeared, 'common (almost universal) usage' of the terminology refers to RCCBs as "RCDs" (since for many years they were the only type of RCDs around), and refers to RCBOs as "RCBOs".

Hence, unless they were deliberately trying to confuse, I don't think anyone would usually refer to an RCBO as an "RCD", even though that is strictly correct (since RCBOs are "Residual Current Devices")

That don't alter the facts.

Bugger - I made a mistake.


Also - RFC only stands for Ring Final Circuit and not Radial Final Circuit even though it does.

It's just as daft as Winston's "transformer" being only one specific type of transformer and not all things that transform - voltage or anything else.

 

[JohnW2]

That don't alter the facts.

Of course it doesn't - but for those like Jupiter, what they need to know/learn is what is usually (in this case, almost always) meant by the terminology which is "usually used".

It's just as daft as Winston's "transformer" being only one specific type of transformer and not all things that transform - voltage or anything else.

I think that really is an over-simplified generalisation. The vast majority of things which 'transform' (something into something else), of which there are innumerable, are usually referred to by specific names/terms, in order to clarify meaning - rather than just calling them all 'transformers'. If that weren't the case, clear communication would be essentially impossible.

Some of the things that winston doesn't like being called transformers contain transformer(s) which transform AC into DC, other transformer(s) that transform one AC voltage into another AC voltage, some transformer(s) that transform DC with a lot of superimposed AC ripple into DC with less ripple etc. etc.

Kind Regards, John

 

[winston1]

I think that really is an over-simplified generalisation. The vast majority of things which 'transform' (something into something else), of which there are innumerable, are usually referred to by specific names/terms, in order to clarify meaning - rather than just calling them all 'transformers'. If that weren't the case, clear communication would be essentially impossible.

Some of the things that winston doesn't like being called transformers contain transformer(s) which transform AC into DC, other transformer(s) that transform one AC voltage into another AC voltage, some transformer(s) that transform DC with a lot of superimposed AC ripple into DC with less ripple etc. etc.

Kind Regards, John

A transformer in electrical terms is a device that transforms voltage or current by electromagnetic induction.

Transformers never transform AC into DC. That is called a rectifier.

 

[JohnW2]

A transformer in electrical terms is a device that transforms voltage or current by electromagnetic induction. Transformers never transform AC into DC. That is called a rectifier.

Why are you telling me that - don't you understand that, in what I wrote to EFLI, I was essentially agreeing with you?

 

[EFLImpudence]

Transformers never transform AC into DC.

Never what? AC into DC?

That is called a rectifier.

Why is that?

 

[EFLImpudence]

A transformer in electrical terms is a device that transforms voltage or current by electromagnetic induction.

You mean an electromagnetic induction transformer is a device that transforms voltage or current by electromagnetic induction and other transformers transform other things by other methods.

 

[plugwash]

I’ve seen some garage CU’s that only have an RCD (and some MCB’s). There’s no main switch.
In that situation, the RCD is ostensibly the main switch?

Not just garage CUs, when RCDs first came in there were full-sized CUs that had RCD main switches. My granny had one.

 

[winston1]

You mean an electromagnetic induction transformer is a device that transforms voltage or current by electromagnetic induction and other transformers transform other things by other methods.

No. There are no other transformers in electrical terms.

 

[winston1]

Why is that?

I don't know why a rectifier is called a rectifier. What would you call it?

 

[JohnW2]

I don't know why a rectifier is called a rectifier.

I think you will find that one of meanings of the origins of the word "rectify", ultimately from Latin, is "to make straight" - so I suspect it might be a (not very accurate!) reference to what it does to waveforms?