Plastic switch in external meter box

It is raining nuisance callers now and my contacts on the phone are nearly up to T**tAvoidtimewaster567, though way behind notanotherconsultant2394567.

 

So isn't a swithfuse just one example of a 1-way distribution board? They might (or might not) comply with different standards - but BS 7671 doesn't define things in terms of which standards they are constructed to meet, but in terms of their fundamental components and functionality. If it's "an assembly containing switching or protective devices ... associated with one or more outgoing circuits fed from one or more incoming circuits ... " BS 7671 seems to consider it a distribution board.

No. I stand by FUSED SWITCH [ or switch fuse] like a KMF, not being like a DB. There is one neutral connection in, and one neutral connection out. Same for the earth conductor. There is no option for other neutrals or CPCs unless you are particularly rough.


You left out a fundamental part of the BS7671 definition of what is a DB.
"......together with terminals for the neutral  and circuit protective conductors"

Consumer Units and the Distribution Boards that are similar switchgear to Consumer Units have neutral and CPC bars. The genuine old style one way distribution boards like wylex/ MEM had a rewirable or HRC fuse or plug in retro MCB, but also had an earth bar and a neutral bar.

 

Now there I've got to differ - Consumer Unit got their name back in the day when rewireable fuses were still king - 'trip switches' (MCBs etc) are just the current fashion. We may well be returning to the situation were consumers may have to pull out and replace bits of their CUs to keep their installation in a serviceable condition if the current fad for SPDs (with replaceable cartridges) continues too.

Perhaps the point was not clear. Consumer Units are a particular  DB for use in Domestics. A KMF  has a HRC fuse that is not that consumer friendly to remove unless you are familiar with them. There is no indication that they have blown; same for BS3036, but of course, you can pull this rewireable out and see if the wire is healthy or not. I may also add that a SPD does have an indicator on healthyness. All fairly consumer friendly, but not necessarily very helpful as nothing will ever be done about it.


 

BS 7671's requirement for a main switch (or main circuit breaker) is that it is as near as practical to the origin of the installation (462.1.201) - which is just what you want if you cut off power to the entire premises for whatever reason - so I still say (unless one is provided by the DNO) the the switch on a switchfuse should be used in preference to one on a downstream CU - especially by ordinary persons who are less likely to understand the distinction and/or be aware exactly where the submain cable runs for example.

We will start to run into a bit of difficulty with that in a block of Flats with metering all in a communal location, especially if there are off-peak distribution also where we are then in "fifty fifty or phone a friend " territory as all the labels are missing.

Even when the KMF is used as an isolator, that does not qualify it as a DB.


This thread topic is loaded with proverbial cul de sac's where something is always parked in the maneuvering space; see earlier replies about SFCUs for example. Careful what you wish for when what are product standard issues are levered into BS7671. [edited]


Yes, KMFs fit in small places where your genuine one way distribution board will not, some of the time.

A KMF for a submain in a box, outside, no problem. Inside, I would fit a one way distribution board?


As a direct replacement for a faulty one [KMF], depends if space allows, but as you know, space is not likely to allow that in an existing as the small space was why the KMF was put there in the first place.

It is raining nuisance callers now and my contacts on the phone are nearly up to T**tAvoidtimewaster567, though way behind notanotherconsultant2394567.

 

So isn't a swithfuse just one example of a 1-way distribution board? They might (or might not) comply with different standards - but BS 7671 doesn't define things in terms of which standards they are constructed to meet, but in terms of their fundamental components and functionality. If it's "an assembly containing switching or protective devices ... associated with one or more outgoing circuits fed from one or more incoming circuits ... " BS 7671 seems to consider it a distribution board.

No. I stand by FUSED SWITCH [ or switch fuse] like a KMF, not being like a DB. There is one neutral connection in, and one neutral connection out. Same for the earth conductor. There is no option for other neutrals or CPCs unless you are particularly rough.


You left out a fundamental part of the BS7671 definition of what is a DB.
"......together with terminals for the neutral  and circuit protective conductors"

Consumer Units and the Distribution Boards that are similar switchgear to Consumer Units have neutral and CPC bars. The genuine old style one way distribution boards like wylex/ MEM had a rewirable or HRC fuse or plug in retro MCB, but also had an earth bar and a neutral bar.

 

Now there I've got to differ - Consumer Unit got their name back in the day when rewireable fuses were still king - 'trip switches' (MCBs etc) are just the current fashion. We may well be returning to the situation were consumers may have to pull out and replace bits of their CUs to keep their installation in a serviceable condition if the current fad for SPDs (with replaceable cartridges) continues too.

Perhaps the point was not clear. Consumer Units are a particular  DB for use in Domestics. A KMF  has a HRC fuse that is not that consumer friendly to remove unless you are familiar with them. There is no indication that they have blown; same for BS3036, but of course, you can pull this rewireable out and see if the wire is healthy or not. I may also add that a SPD does have an indicator on healthyness. All fairly consumer friendly, but not necessarily very helpful as nothing will ever be done about it.


 

BS 7671's requirement for a main switch (or main circuit breaker) is that it is as near as practical to the origin of the installation (462.1.201) - which is just what you want if you cut off power to the entire premises for whatever reason - so I still say (unless one is provided by the DNO) the the switch on a switchfuse should be used in preference to one on a downstream CU - especially by ordinary persons who are less likely to understand the distinction and/or be aware exactly where the submain cable runs for example.

We will start to run into a bit of difficulty with that in a block of Flats with metering all in a communal location, especially if there are off-peak distribution also where we are then in "fifty fifty or phone a friend " territory as all the labels are missing.

Even when the KMF is used as an isolator, that does not qualify it as a DB.


This thread topic is loaded with proverbial cul de sac's where something is always parked in the maneuvering space; see earlier replies about SFCUs for example. Careful what you wish for when what are product standard issues are levered into BS7671. [edited]


Yes, KMFs fit in small places where your genuine one way distribution board will not, some of the time.

A KMF for a submain in a box, outside, no problem. Inside, I would fit a one way distribution board?


As a direct replacement for a faulty one [KMF], depends if space allows, but as you know, space is not likely to allow that in an existing as the small space was why the KMF was put there in the first place.