New bathroom fan. Isolator required?

[ebee]

"Yes.
House is extended sideways. The 16A is the old part of the house and outside lights.
Newer 'wing' is on a 6A."

a 5A or 6A circuit for Lighting would not bother me if no 3A fuse for fan, 10A circuits for lighting are not very common but do exist, I think I would be now wanting to fuse down the fan a bit. 16A for lighting is OTT and needs addressing by the sound of it - unless it`s actually fused down somewhere else. and we really should be thinking about RCDs being needed for almost everything these days too - OK there`s still lots of houses with No RCDs and of those with a lot are only on certain circuits and then again the majority by far will be type AC anyway not type A and having said that I am sure some of my old rewires with rewireable fuses and no RCDs are still in operation but none the less I think some updating might be required

 

[mcprinter]

Have you checked them?

Definitely no RCD within those photos

We have been here 20+ years. No idea when the CU went in.
I must have done a basic check on what does what at some point.
I add notes to the paper when I find things like sockets in the kitchen on different circuits.
This MCB has tripped over the years when incandescent light bulbs have popped.
99% sure it is just a lighting circuit on the 16A. Not aware of any other fusing on it.

Should the 16A MCB be replaced with a 6A?

 

[mcprinter]

Fair enough. As has been said, it's entirely your decision, given that there is no regulatory requirement.

Do I take it that the room has no window (i.e. 'natural light', during the hours of daylight)?

Kind Regards, John

Reasonable natural light.
Just makes sense to be able to isolate it separately for replacement/cleaning.

 

[JohnW2]

Reasonable natural light. Just makes sense to be able to isolate it separately for replacement/cleaning.

Fair enough - as I said, your choice/decision.

As I'm sure you will understand, my point was that if there is reasonable natural light,you could presumably do the maintenance/cleaning during daylight hours without the need for an isolator.

 

[plugwash]

16A for lighting is OTT and needs addressing by the sound of it

IIRC BS7671 used to specify a max of 6A for SES/SBC lampholders and a max of 16A for ES/BC lampholders, but it was changed at some point (maybe the 17th edition) to a max of 16A for all of the aforementioned lampholder types.

 

[JohnD]

IIRC BS7671 used to specify a max of 6A for SES/SBC lampholders and a max of 16A for ES/BC lampholders, but it was changed at some point (maybe the 17th edition) to a max of 16A for all of the aforementioned lampholder types.

But lightswitches are usually rated at 10A

 

[JohnW2]

But lightswitches are usually rated at 10A

Yes, but that relates to the current that may flow through it for a significant time, and no light would ever draw anything remotely like 10A in normal operation, and incredibly unlikely as an 'overload' current (if the light could create an overload).

'Fault currents' are obviously a different issue, and it has to be accepted (just as it is with cables and all accessories) during fault conditions a switch may carry (very briefly, before an OPD operates) a current dozens of times greater than its 'rating'

 

[JohnW2]

IIRC BS7671 used to specify a max of 6A for SES/SBC lampholders and a max of 16A for ES/BC lampholders, but it was changed at some point (maybe the 17th edition) to a max of 16A for all of the aforementioned lampholder types.

I would think that the current situation makes most sense, since a person designing and installing a lighting circuit (including its OPD) cannot know what sort of lamp holders (or other light fittings, or other loads) may come to be supplied by that circuit.

 

[ebee]

I don`t suppose it does not count as helpful that some manufacturers/importers label the fan connection terminals or the instruction manuals differently and that can cause confusion. I`ve also come across a few cases where the initial installer appears to have changed connections because they thought that, as supplied, they were wrong (Oh yes, some folk love to meddle! I have even come across a case where an "Electrician" stripped down and attempted to alter the DP Mainswitch on a Wylex Consumer unit , "Red Rocker" range because orientation of consumer unit switch changed, apparently he thought that there had been a mistake at the factory. I know it baffled a few but one of them attempted to rectify this "mistake". The mind boggles LOL).

The L, N, T is usually Line (permanent) Neutral and Trigger, usually, but I have seen them with L and T transposed too. Whether by design or subsequent meddling I am not convinced either way.
Then Some are L, N and S/L or SL or LS or L/S and some present L as PL or P/L , (P as in Permanent) .
I suppose that seeing an interpretation of L being a switched Line and T being to run the Timer module was the way of thinking.
Anyway I would read the instruction manual wiring diagram to see what the manufacturer actually intended (OK it might have actually been the importer who actually created the instruction wiring diagrams I suppose).

There must be a moral there to the story but I haven`t a clue what it is!

 

[ebee]

PS - I have a tale to tell that I`ve told before - the very first add your own car alarm and immobiliser unit, gave me a problem.

 

[mcprinter]

IIRC BS7671 used to specify a max of 6A for SES/SBC lampholders and a max of 16A for ES/BC lampholders, but it was changed at some point (maybe the 17th edition) to a max of 16A for all of the aforementioned lampholder types.

Does this mean my 16A MCB is actually OK?

 

[Murdochcat]

Does this mean my 16A MCB is actually OK?

Debateable ((I would say not acceptable) BUT you should get your CU / installation looked at and as you are adapting your fixed wiring you are required to add RCD protection to the circuit you are changing

 

[mcprinter]

Debateable ((I would say not acceptable) BUT you should get your CU / installation looked at and as you are adapting your fixed wiring you are required to add RCD protection to the circuit you are changing

I got the same advice when working on my neighbours kitchen and he wanted an extra socket.
He still has rewireable fuses.
I followed the advice and did not fit an extra socket.
I did move the cooker outlet (surface mounted no cable change). Even this I believe is classed as a 'change'?

Is a RCBO in place of the MCB acceptable?

 

[Murdochcat]

Is a RCBO in place of the MCB acceptable?

Yes. Needs to be the same make as the CU if it is lights only then do use a 6A

Looking at the age of your installation you should also check your earthing and bonding are up to regs too

 

[ebee]

Looking at the age of your installation you should also check your earthing and bonding are up to regs too

Why ?