2 spurs from a Junction Box....worried?

[MFS Electrical]

Yeah, but that's also what makes it somewhat scary

Yup it would be much better if it was all black and white but it’s grey so the people that wrote it can weasel out throw you under the bus and say thats not how we meant it if you follow it and end up burning down a house killing a family of 5 sheep and destroying a museum.

 

[SparkyChick]

Yup it would be much better if it was all black and white but it’s grey so the people that wrote it can weasel out and say thats not how we meant it if you follow it and end up burning down a house killing a family of 5 sheep and destroying a museum.

As @Murdoch said earlier, I wish they'd focus on clarity instead of climbing into bed with the manufacturers to push their fancy (read expensive) new safety devices.

 

[MFS Electrical]

As @Murdoch said earlier, I wish they'd focus on clarity instead of climbing into bed with the manufacturers to push their fancy (read expensive) new safety devices.

That would be epic but there is a probably another hidden agenda as well they know exactly what they want to say but it will take another 24 editions and multiple amendments for it to be clear - the IET is a very profitable business indeed

 

[SparkyChick]

That would be epic but there is a probably another hidden agenda as well they know exactly what they want to say but it will take another 24 editions and multiple amendments for it to be clear - the IET is a very profitable business indeed

So maybe the end of next year then we might get some clarity? Either that or we'll all be broke and out of business

 

[Deuce]

It's still on my mind too and I'm in bed now!!

I'm resolved though, it IS two spurs, it just is. Certainly in every way that matters, it is 2 spurs.

The regs don't cover this. They go far enough to limit overloading of a single spur, they don't cover the possibility of putting 2 in one box because you just don't need specific regulation for that.

As for is it right or wrong to do it this way... If it's not dangerous and doesn't explicitly break regs then it's not wrong. All we have here is something a little unusual. But hey, saved on a second jb and shortened the install time too.

Just a shame an mf box wasn't used for the sake of compliance, but that's a different topic really. And a topic I have some divisive views on so maybe another thread for that tomorrow night

 

[Octopus]

It's still on my mind too and I'm in bed now!!

I'm resolved though, it IS two spurs, it just is. Certainly in every way that matters, it is 2 spurs.

The regs don't cover this. They go far enough to limit overloading of a single spur, they don't cover the possibility of putting 2 in one box because you just don't need specific regulation for that.

As for is it right or wrong to do it this way... If it's not dangerous and doesn't explicitly break regs then it's not wrong. All we have here is something a little unusual. But hey, saved on a second jb and shortened the install time too.

Just a shame an mf box wasn't used for the sake of compliance, but that's a different topic really. And a topic I have some divisive views on so maybe another thread for that tomorrow night

and it uses a screw type JB in an inaccessible location .....

 

[telectrix]

all depends on how you define "inaccessible".if a screw type JB is installed under a screwed down floorboard trap, it's accessible by the use of a screwdriver: same as the screw terminals in a CU are accessible by the use of a screwdriver. now where's my tin hat?

 

[Deuce]

and it uses a screw type JB in an inaccessible location .....

It's a nonsense imo. Make it as accessible as you want and no one will inspect/maintain it until there is a fault someday. And does a correctly torqued screw terminal work free over time? In theory it can... But in reality I find it not to be the case.

We have a number or mobile machines here with 63a 3ph plugs on a trailing lead. As such, at least once a year as part of testing the plugs are opened and the terminals checked - and they're never loose! Not even fractionally. Sure, it helps that they use screw clamp terminals but on the other hand a plug on a trailing lead is in theory an item most exposed to movement of the cable entering it.

I also see others using a drop of threadlock on the terminal screws to prevent and future movement.

The OPs installation doesn't qualify as 'accesible' I know. But it emphatically is accessible by anyone with the ability and tools to open the JB to inspect it, as the only barrier to access is a floorboard fixed with 2 screws - it's as accessible as the JB cover is removable.

The regs say mf under floorboards etc as it's easier to have a blanket rule for all of course. Doesn't do much to encourage common sense thinking though. I personally think the whole MF thing is unnecessary in many such cases and that a good installer can achieve the same long term performance with a screw terminal in anycase.

Let the debate rage

 

[SparkyChick]

I can't speak for @Murdoch but I believe our views on this are pretty similar... it's less about how easy it is to access (at the moment it's easy because there are no fitted carpets), it's more about knowing it's there.

My mantra on the subject is if you can't see it easily when the job is done, make it maintenance free. It saves all the arguments, all the potential issues around subsequent inspection.

That's my personal view, it complies with the regs and no one is likely to change my mind on that

 

[Octopus]

The OPs installation doesn't qualify as 'accessible' I know.

But it emphatically is accessible by anyone with the ability and tools to open the JB to inspect it, as the only barrier to access is a floorboard fixed with 2 screws - it's as accessible as the JB cover is removable.

which renders it inaccessible - are you suggesting that we need to be prepared to lift ALL floorboards to inspect whats hidden - no

There is a reg that says something about items being accessible and under floor boards ISN'T

 

[Deuce]

I can't speak for @Murdoch but I believe our views on this are pretty similar... it's less about how easy it is to access (at the moment it's easy because there are no fitted carpets), it's more about knowing it's there.

My mantra on the subject is if you can't see it easily when the job is done, make it maintenance free. It saves all the arguments, all the potential issues around subsequent inspection.

That's my personal view, it complies with the regs and no one is likely to change my mind on that

which renders it inaccessible - are you suggesting that we need to be prepared to lift ALL floorboards to inspect whats hidden - no

There is a reg that says something about items being accessible and under floor boards ISN'T

Yes, renders it technically inaccessible as defined by the regs.

But my point is that we also wouldn't know if an MF box was in the same place. So why is MF better? Because in theory an MF connection will last at least as long as the realistic lifespan of the circuit it's on. Providing the connection is made correctly...

I love wago connectors, I use them to allow for quick reconfiguration when I'm switching different control components, but it IS possible to make an partially locked connection which will pass testing - until the cable is given a little tug down the line. I see it happen.

Wouldn't happen to anyone who cares enough to give the wires a good tug after snapping the connectors down to make sure - but the same type of conscientious person probably never struggled to make a traditional screw terminal connection that would sit happily for decades and remain sound.

 

[johnduffell]

The OPs installation doesn't qualify as 'accesible' I know. But it emphatically is accessible by anyone with the ability and tools to open the JB to inspect it, as the only barrier to access is a floorboard fixed with 2 screws - it's as accessible as the JB cover is removable.

I agree, and be7671 doesn't define accessible. this kind of thing is much more common in the design of non domestic installations, however as sparky chick says it's all about the ability to find. Attach a permanent label to the floor and provide layouts at the DB and you're only limited by whether you can use a screw driver. However shove a joint under a random floorboard and no one would think to look under every possible board, also laminate floor fitters aren't going to think twice about sticking 6mm ply down and adding a floor finish.
This is not so much about the regs but about good professional judgment granted to the designer to use by the regs themselves. Use it wisely! Maybe a new informative appendix could be written to cover that

 

[Baddegg]

So in conclusion OP your house may or may not burn down.......your welcome

 

[Octopus]

Yes, renders it technically inaccessible as defined by the regs.

But my point is that we also wouldn't know if an MF box was in the same place. So why is MF better? Because in theory an MF connection will last at least as long as the realistic lifespan of the circuit it's on. Providing the connection is made correctly...

I love wago connectors, I use them to allow for quick reconfiguration when I'm switching different control components, but it IS possible to make an partially locked connection which will pass testing - until the cable is given a little tug down the line. I see it happen.

Wouldn't happen to anyone who cares enough to give the wires a good tug after snapping the connectors down to make sure - but the same type of conscientious person probably never struggled to make a traditional screw terminal connection that would sit happily for decades and remain sound.

Wago's are only MF in certain applications ....... I use the Hager units

 

[Octopus]

I agree, and be7671 doesn't define accessible. this kind of thing is much more common in the design of non domestic installations, however as sparky chick says it's all about the ability to find. Attach a permanent label to the floor and provide layouts at the DB and you're only limited by whether you can use a screw driver. However shove a joint under a random floorboard and no one would think to look under every possible board, also laminate floor fitters aren't going to think twice about sticking 6mm ply down and adding a floor finish.

That's just plain stupid ......

I've said on many occasions that BS 7671 should define accessible and lifting a carpet / lino/ tiles and floorboards ISN'T accessible - maps or notes provided.............

 

[johnduffell]

That's just plain stupid ......

I've said on many occasions that BS 7671 should define accessible and lifting a carpet / lino/ tiles and floorboards ISN'T accessible - maps or notes provided.............

Agree it's stupid but my point is there are several unworkable conditions needed to make it ok in my mindd. I understood it was simply a screwed down finished floorboard, but as stated any additional finish would just cover the labelling etc.

 

[johnduffell]

So in conclusion OP your house may or may not burn down.......your welcome

At least someone is thinking about the poor op. He's probably retrained to be an electrican and rewired his place by now!

 

[Octopus]

Agree it's stupid but my point is there are several unworkable conditions needed to make it ok in my mind. I understood it was simply a screwed down finished floorboard, but as stated any additional finish would just cover the labelling etc.

I absolutely disagree with you - NOTHING makes a non MF connection under a floorboard acceptable

 

[Baddegg]

At least someone is thinking about the poor op. He's probably retrained to be an electrican and rewired his place by now!

I heard he’s moved house.......all gas no electrics.......that’s what I heard anyway

 

[Pete999]

ACCESSIBLE | definition in the Cambridge English Dictionary - https://dictionary.cambridge.org/us/dictionary/english/accessible

 

[Deuce]

I agree, and be7671 doesn't define accessible. this kind of thing is much more common in the design of non domestic installations...

This is why I sometimes come at these debates from a different angle. In industrial design not much about placement is standard enough for regs to cover it. All houses have floorboards and walls where things can be hidden, so it's easy enough to define all such places as needing MF.

Beyond domestic, there is just too much variability though. In a factory process line something could be totally inaccessible without major effort for a variety of obscure reasons, so it really does all hinge on common sense. In the same way bathrooms and kitchens are zoned in respect of them being wet areas. In my world a space not at all zoned could represent similar risks and it's up to me to identify those risks and factor them in to whatever is being installed.

Different worlds I guess... But the risks are in the end, generally comparable.

 

[johnduffell]

Good idea @Deuce you have persuaded me that an informative appendix defining zones for accessibility would help a lot.
Interestingly part m defines accessibility for their purposes as between 450 and 1200 from ffl, so in New builds most screw connections would be within that range anyway. But I'm not suggesting that is a useful definition for our purposes

 

[DPG]

It's not useful as far as accessibility of connections no - it is purely aimed at ensuring accessibility of user operated switches /sockets etc. Nothing wrong with a jb being on top of a kitchen cupboard for example - it is still accessible.

 

[Octopus]

ACCESSIBLE | definition in the Cambridge English Dictionary - https://dictionary.cambridge.org/us/dictionary/english/accessible

Hum

Inaccessible?

 

[Pete999]

Hum

Inaccessible?

Yes I know Mate just before I hit the post button doooooh Funny how you know you have it wrong, but you still can't stop the finger that's hovering over the send button only to realise what you have done, and hope nobody notices your error. And I haven't any alcohol, yet.

 

[MDJ]

Yes I know Mate just before I hit the post button doooooh Funny how you know you have it wrong, but you still can't stop the finger that's hovering over the send button only to realise what you have done, and hope nobody notices your error. And I haven't any alcohol, yet.

P!SS head lol

 

[Pete999]

P!SS head lol

Not true how dare you, go and stand on the naughty step you bad Man

 

[Dangerous Brian]

For those who are worried about overloading terminations by taking two spurs, each to one twin sso from one 30A joint box connected to a ring final cct. Consider a spur from a twin sso on the ring to one twin sso. If these sockets are compared to the two spurs from one joint box you will see the point loading on the rfc is the same in both cases. The load in both cases comes from a single connection to the rfc.

 

[Pete999]

For those who are worried about overloading terminations by taking two spurs, each to one twin sso from one 30A joint box connected to a ring final cct. Consider a spur from a twin sso on the ring to one twin sso. If these sockets are compared to the two spurs from one joint box you will see the point loading on the rfc is the same in both cases. The load in both cases comes from a single connection to the rfc.

One twin 13 Amp Socket out let IS ONE SPUR Brian, not two spurs taken from the same point on a RFC.

 

[Lucien Nunes]

Brian's point is exactly the same as the one I made in post #121 that 11 people liked. The key is that the terminals feeding the two spurs are in a junction box, not the back of another socket outlet. The loading is exactly the same with two spurs from one JB, as with one spur from a socket outlet, as in both cases there are two socket outlets loading a single node in the RFC.

In general the regs don't differentiate between an unfused spur taken from a socket outlet and one taken from a junction box. But here, it's relevant because it eliminates any argument about overloading, regardless of any other factors.

 

[Pete999]

Brian's point is exactly the same as the one I made in post #121 that 11 people liked. The key is that the terminals feeding the two spurs are in a junction box, not the back of another socket outlet. The loading is exactly the same with two spurs from one JB, as with one spur from a socket outlet, as in both cases there are two socket outlets loading a single node in the RFC.

In general the regs don't differentiate between an unfused spur taken from a socket outlet and one taken from a junction box. But here, it's relevant because it eliminates any argument about overloading, regardless of any other factors.

Not going there again Lucien, said my piece, was stupid of me to react to Brian's post.

 

[SparkyChick]

*DING* *DING* - Round 2

I think we've done the subject to death and we have concluded that there are two camps... acceptable and not acceptable, and peoples residency in those camps appears to be largely down to interpretation of the regulations and/or their view on whether it's good practice or not.

But one thing I think most of us are agreed on is that under normal circumstances we wouldn't do it this way ourselves.

 

[Dunc N]

You know its a mess so why not do it right so that you have no further worries?

 

[Toneyz]

When was taking a spurred double socket from another stopped 15th to16th?

 

[snipersmith87]

I dont see how putting 2 x JB a foot apart makes any difference electrically provided the JB is sound. The JB is on a leg between 2 points of a ring. The ring cable will carry the same load in each scenario. Theres no danger of overload to the spurs as its 2 x seperate twins off one point of the ring. Wired correctly. Adequate size cable. So why put extra connections in a circuit that doesnt need it??

Completely different to spurring twice off an outlet.

 

[Toneyz]

I dont see how putting 2 x JB a foot apart makes any difference electrically provided the JB is sound. The JB is on a leg between 2 points of a ring. The ring cable will carry the same load in each scenario. Theres no danger of overload to the spurs as its 2 x seperate twins off one point of the ring. Wired correctly. Adequate size cable. So why put extra connections in a circuit that doesnt need it??

Completely different to spurring twice off an outlet.

Nor do I, but if that was the scenario those who say it does not comply would be satisfied by a short piece of 2.5 between two junction boxes.

 

[Octopus]

Nor do I, but if that was the scenario those who say it does not comply would be satisfied by a short piece of 2.5 between two junction boxes.

2 x MF, and an extra piece of cable - yes that would be ideal and then, like the pretty schematic in BS 7671 there would only be 3 cables at each point ....

 

[SparkyChick]

I think it's time to close this thread, it's unlikely any new views will be put forward (as there are essentially only two... it complies and it does not) and well, at 16 pages I think it's run it's course.