30A JB's and 32A ring final circuits

[SplitJugular]

ive been having a dispute with another electrician about using 30A JB's on rings

a ring is made up of 2 legs of 2.5mm T+E,
2.5mm T+E ref method C has current carrying capacity of 27A

now surely the JB has to be rated higher than the cable, but using a 30A jb although this is less than the 32A MCB its only joining one half of the circuit and is still higher than the rating of the cable
the arguement is that he thinks i should be using 45A JB's as they are rated above the MCB

whats peoples feeling on this matter as this is the first electrician ive met in 10 years that ever had a problem joining a ring with 30A JB's

i also did a little reasearch and although i couldnt find the correct reference in the regs book wikipedia stated that the cable size in a ring should be rated at no less than 2/3 ( two thirds) of the MCB
meaning that the cable rating has to at least be 21.333A so a 30A jb would be sufficient by 8.66A

a also if 30A JB's were not sufficient why do wholesalers not stock a 32A jb?

 

[telectrix]

you're right. your mate's wrong. sorted.

 

[Flanders]

Your right the 32 amp is shared over the to legs of the RFC

 

[Octopus]

out of interest where were you putting the JB? under the floor?

 

[SplitJugular]

yeh thought as much, this is what the NIC man had apparently told him on the inspection visit last friday, am i right in saying that during an NIC visit they may say something like this to challenge your knowlege of the regs and this would be an invitation to discuss whats right and wrong, being that the regs are not a statutory document and in a sense they are just theory, surely arguing this would prove to the NIC man that i have sound reasoning behind my work,

ive heard from other collegues that they were asked why back boxes were not earthed (apparently this has been dropped in the regs)
"why are back boxes not earthed?"
"because they dont have to be"
"what about when the face plate is taken off the box is then not earthed!
"you shouldnt work on an installation whilst it is live"

the last line my friend said apparently seemed to be the answer the NIC man was looking for

 

[SplitJugular]

Murdoch, this wasnt really part of the issue he's saying it as a general rule no matter where the jb is put on the circuit, and the whole accesible area is a very grey area, as im more than confident pulling up a fitted carpet and re-instating it, thus this would make a joint under the floor boards, and carpet an accesible area for me. inaccessable to me means out of reach even with access equipment or out of possible sight

 

[kingeri]

Murdoch, this wasnt really part of the issue he's saying it as a general rule no matter where the jb is put on the circuit, and the whole accesible area is a very grey area, as im more than confident pulling up a fitted carpet and re-instating it, thus this would make a joint under the floor boards, and carpet an accesible area for me. inaccessable to me means out of reach even with access equipment or out of possible sight

I totally disagree with that. Okay, you can interpret certain elements of the regs this way or that, but I would say that accessible means you don't have to rip up carpets and boards to get to it!

 

[Tiny Spark]

yeh thought as much, this is what the NIC man had apparently told him on the inspection visit last friday, am i right in saying that during an NIC visit they may say something like this to challenge your knowlege of the regs and this would be an invitation to discuss whats right and wrong, being that the regs are not a statutory document and in a sense they are just theory, surely arguing this would prove to the NIC man that i have sound reasoning behind my work,

ive heard from other collegues that they were asked why back boxes were not earthed (apparently this has been dropped in the regs)
"why are back boxes not earthed?"
"because they dont have to be"
"what about when the face plate is taken off the box is then not earthed!
"you shouldnt work on an installation whilst it is live"

the last line my friend said apparently seemed to be the answer the NIC man was looking for

He would be buggered if he checked my work then, I still earth my back boxes LOL
I just consider it good practice and for the amount of time it takes I dont see why not even though it does not need to be done anymore.

As for the 30A JB thing, well thats the first time ive heard of that one....

 

[SplitJugular]

I totally disagree with that. Okay, you can interpret certain elements of the regs this way or that, but I would say that accessible means you don't have to rip up carpets and boards to get to it!

either way Murdoch its off topic and not the answer i was looking for, ive been on many different forums today and all of them have the same thread about 'accesible area' and no one agrees, look at it this way if i put a JB in a cupboard under the stairs that was small ish but big enough for me to get into (lets not flatter myself i am 14 Stone) but then my workmate sparkey who is 22 stone cant fit in cus he's too fat, is that jb now inaccessible? access depends on personal skill and commitment,

to say a fitted carpet is denying access would be the same as saying that light switches that were painted/silliconed in were inacessible because the customer wouldnt want the walls ruined aswell as the carpet??

 

[7029 dave]

30amp jb no problem what so ever

 

[SplitJugular]

He would be buggered if he checked my work then, I still earth my back boxes LOL
I just consider it good practice and for the amount of time it takes I dont see why not even though it does not need to be done anymore.

As for the 30A JB thing, well thats the first time ive heard of that one....

yup im with you i would do it as good practice but curious as to weather this is something the NIC do (give testing questions) i see why its a good thing and is a good indication of weather or not someone is just chancing it, i really want to know because im going for NIC registration soon and dont know if ill end up aruing my way off the NIC list

 

[Farmelectrics]

Don't use jbs row over lol

 

[SplitJugular]

Don't use jbs row over lol

not an option unfortunatly, i would if i had my way join with crimps in a box all the time, but this guy has for some reason got something against crimps and complains any time he see's them
(he gives me the work but it is council work and i see it as a waste of my council tax some of the lengths he goes to)

 

[Risteard]

And what about a 20A junction box? The Wiring Regulations only require that the current-carrying-capacity of the live conductors in a ring final circuit is at least 20A. Although I use 30A as it is easier worked with and prevents others giving off about you lol

 

[Octopus]

either way Murdoch its off topic and not the answer i was looking for, ive been on many different forums today and all of them have the same thread about 'accesible area' and no one agrees, look at it this way if i put a JB in a cupboard under the stairs that was small ish but big enough for me to get into (lets not flatter myself i am 14 Stone) but then my workmate sparkey who is 22 stone cant fit in cus he's too fat, is that jb now inaccessible? access depends on personal skill and commitment,

to say a fitted carpet is denying access would be the same as saying that light switches that were painted/silliconed in were inacessible because the customer wouldnt want the walls ruined aswell as the carpet??

But in your example you were saying under the floor boards, under the carpet - which is INACCESSIBLE.

Accessible is within reach without having to lift a floor board or moving a 120KG American Fridge Freezer

 

[Farmelectrics]

Finish the job and try not to work with the guy again

 

[rattlehead85]

A J.B under a floor is deemed inaccessible especially for inspection and testing purposes mainly because an inspector will not reasonably know where such a box is situated unless suitable plans and drawings are provided with the installation which in reality is NEVER!!

 

[Tiny Spark]

not an option unfortunatly, i would if i had my way join with crimps in a box all the time, but this guy has for some reason got something against crimps and complains any time he see's them
(he gives me the work but it is council work and i see it as a waste of my council tax some of the lengths he goes to)

Sounds like the guy is very set in his ways.
Personally I love crimps and would rather them to a JB.
If I do have to use a form of JB I would prefer a waygo type (not sure thats how you spell it but you know the maintenance free type)

As for the accessible thing it is open to interpretation, But I think its the same as most other things in this trade whereby you have to use a little common sense and take it with a pinch of salt.

I would say if you need to damage something (pulling up boards for instance) then its not accessible.
I think it should be accessible with only basic tools and have enough room around it to be able to work on it.

 

[Guitarist]

JB under floorboards covered by carpet is inaccessible, simple.
Using JB's in this day and age when we have Wagos and lineproducts....Inexcusable. Why even argue the point when we have quick and easy MF kits available.

 

[ExArmy]

under the floor is not accessible. what happens when someone puts down laminate, vinyl or glued down lino??

 

[ExArmy]

JB under floorboards covered by carpet is inaccessible, simple.
Using JB's in this day and age when we have Wagos and lineproducts....Inexcusable. Why even argue the point when we have quick and easy MF kits available.

why indeed, wagos are much quicker and easier to install! and i don't pay for them, the customer does, not that it matters as the labour saving evens it out

 

[jamesBoater]

a also if 30A JB's were not sufficient why do wholesalers not stock a 32A jb?

wholesalers do stock 32 amp Junction boxes we use the Hager MF ones when needed.

 

[MDJ]

ive been having a dispute with another electrician about using 30A JB's on rings

a ring is made up of 2 legs of 2.5mm T+E,
2.5mm T+E ref method C has current carrying capacity of 27A

now surely the JB has to be rated higher than the cable, but using a 30A jb although this is less than the 32A MCB its only joining one half of the circuit and is still higher than the rating of the cable
the arguement is that he thinks i should be using 45A JB's as they are rated above the MCB

whats peoples feeling on this matter as this is the first electrician ive met in 10 years that ever had a problem joining a ring with 30A JB's

i also did a little reasearch and although i couldnt find the correct reference in the regs book wikipedia stated that the cable size in a ring should be rated at no less than 2/3 ( two thirds) of the MCB
meaning that the cable rating has to at least be 21.333A so a 30A jb would be sufficient by 8.66A

a also if 30A JB's were not sufficient why do wholesalers not stock a 32A jb?

You only join one leg though in the JB and that's rated at nowhere near 32amp???

 

[rattlehead85]

under the floor is not accessible. what happens when someone puts down laminate, vinyl or glued down lino??

Then your stuffed if a fault appears. Hammer and Chisel and an angry tenant is the scenario.

 

[elliot123]

Going back since when did metal back boxes not have to be earthed? Only an apprentice but have always been taught earth my back boxes college and onsite

 

[Guitarist]

Going back since when did metal back boxes not have to be earthed? Only an apprentice but have always been taught earth my back boxes college and onsite

If a backbox has at least 1 fixed lug, then it does not need to be earthed. That said, I always do, as do many "old school" electricians.

 

[elliot123]

Spouse you learn something new everyday, only takes a minute extra to put a earth in so won't stop

 

[telectrix]

that came in round about 2004 or a bit before. under 16th. still good practice to fit a fly lead though.

 

[Guitarist]

Spouse you learn something new everyday, only takes a minute extra to put a earth in so won't stop

Not sure that I like being called your spouse.... My wife may have something to say about that....

 

[Guitarist]

that came in round about 2004 or a bit before. under 16th. still good practice to fit a fly lead though.

Indeed.

 

[Brightspark2]

Using JB's in this day and age when we have Wagos and lineproducts....Inexcusable.

The Hager MF JB's are good. I like them...


Also OP under the floor is definitely inaccessible!...

 

[amo]

Yes use crimps or run a new length of cable

 

[Tiny Spark]

I always do, as do many "old school" electricians.

Oiii!!

Who you calling old!?

 

[gazj82]

What are your guys thoughts on in line crimps on steel trunking. Got told by some other sparks, it's not in an acessable enclosure, or an acceptable joint.

I told him he was talking rubbish. It's the same as the lugs you crimp on in your mains incoming cables! And if trunking isn't accesible when it has a lid! Well! I won't even say the words I thought to sum him up

What are your thoughts?

 

[davethsparky]

Well with health and safety considerations you may actually need two people to safely manoeuvre a full length trunking lid so you may need to cut a short length just to cover the joint. Then you'd best put a big yellow sticker on it warning of the maximum voltage present. Then a big label identifying the fact that the joint is there. And install a light near it so that you can see it properly and record its location on the plans. And get the trunking tested to ensure it meets all the current product standards for an enclosure.

Jeez its a big metal box designed specifically to contain electrical wiring, who on earth says you can't have a maintainance free joint in there? Hell a lot of it is accessible so you could use your screw terminals of choice, everyone loves to pop the lid off of a trunking and get attacked by sprawling connector blocks!

 

[Lucien Nunes]

The trick is to put the choc block inside a trunking tee or other junction so that when it burns out, you can get at it without taking off a full length of lid. There was a long story behind the pic below but it reminded me why I don't like even MF connections in trunking except for very special situations.

Going back to the OP, what makes a 30A JB a 30A JB? That's the number moulded into the plastic but what does it mean? Under some conditions it's no good for even 15A (Slightly corroded 2.5 lying badly in the terminals, slack screws, installation method pushing cable near max permissible temp) and others its OK for 40 (clean 6.0 meshed together, tight but not overtight screws, low ambient). Even if the whole 32A was on the one JB you could argue the ----, on an RFC you have a comfortable margin.

 

[davethsparky]

Tut tut, trunking lids missing! that's got to be a C2 sir, but what I can do for you is sell you a nice shiny new consumer unit!

 

[SplitJugular]

But in your example you were saying under the floor boards, under the carpet - which is INACCESSIBLE.

Accessible is within reach without having to lift a floor board or moving a 120KG American Fridge Freezer

ok so what you are saying is that the socket behind a 120KG fridge is inaccessible, if that fridge has a 13a plug top then its a portable appliance.


in reply to many other posters on this matter, surely under the floor is inaccessible full stop then, if under boards is ok without carpet, can i tell the customer that they can NEVER put carpet\lamanate down as there are joints under the floor

with enough determination you can get anywhere you need and the level of expected damage when carrying out work is a matter that needs to be discussed with the customer, as i stated earlier if a plasterer re plastered a room and plastered round all the light switches and sockets then you could only remove said sockets or switches by 'scoring' round the edge with a knife and do your best to minimalise damage, these facts did not make the sockets or switches inaccessable its no different to puling up a carpet, i feel that an electrician that doesnt want to pull up a carpet for fear of damage is either imcomputent or lazy.

 

[SplitJugular]

JB under floorboards covered by carpet is inaccessible, simple.
Using JB's in this day and age when we have Wagos and lineproducts....Inexcusable. Why even argue the point when we have quick and easy MF kits available.

dont get me started with this, basically the bloke is the one guy from the council that dishes out a bit of work to us self employed, so i like the work but not this guy, sticky situation,
im all for wagos and push in connectors but he wont let me use the push in connectors i prefer, even though on the box it says suitable for 2.5mm cores and aits rated to 27A (which as i found out is more than enough for RFC) he tells me that i should use a 45A JB, he wont even let me use crimps. recently had to move some dis-boards down to accessible levels and when joining all my cables he wants to use din-rail connectors, nothing wrong with crimps in my experience except when you get those sily crimpers that only work one way??
ultimatly this guy is a complete tool

 

[7029 dave]

an electrician that doesnt want to pull up a carpet for fear of damage is either imcomputent or lazy. Its all part of the job isn't it?

 

[SplitJugular]

Now you are being stupid.

My point is that is there is a floorboard, a carpet, a washing machine or a 120kg fridge freezer in the way then in all these scenarios the jb's or sockets are inaccessible.

End OF.

calling me stupid is very counter productive, at the end of the day its not written in black and white anywhere out there and is open to interitation, and if we are talking stupid you were the one who replied to this thread with something completely off topic and with a question that is dicussed on many other threads titled 'Accessible area?' it seems to me you just want to argue the ---- over something that doesnt have a definitive answer.
now Murdoch what are your thoughts on using 30A jb's on 32A RFC's if you answer this then you actually contributed to this thread rather than fill it with off topic posts, thanks to you the majority of posts are discussing jb location rather than suitability

 

[Octopus]

calling me stupid is very counter productive, at the end of the day its not written in black and white anywhere out there and is open to interitation, and if we are talking stupid you were the one who replied to this thread with something completely off topic and with a question that is dicussed on many other threads titled 'Accessible area?' it seems to me you just want to argue the ---- over something that doesnt have a definitive answer.
now Murdoch what are your thoughts on using 30A jb's on 32A RFC's if you answer this then you actually contributed to this thread rather than fill it with off topic posts, thanks to you the majority of posts are discussing jb location rather than suitability

Using MF JB's under the floor on a ring is OK.

"is open to interitation" - surely you mean interpretation - and yes, I will state clearly AGAIN. Under floor boards is NOT accessible.

 

[kingeri]

To sum up, a JB of rating 20A or greater is suitable for use on a Ring Final Circuit. If the JB is to be situated in a non-accessible location (for example, under floorboards), then in order to comply with BS7671 it must be Maintenance Free and carry the MF symbol.

 

[SplitJugular]

Using MF JB's under the floor on a ring is OK.

"is open to interitation" - surely you mean interpretation - and yes, I will state clearly AGAIN. Under floor boards is NOT accessible.

now you are just being pedantic, im an electrician not an english teacher, also you can clearly state that under floorboards is not accesible but that is still your interpretation of the regs, untill you name is either 'author of regs' or 'GOD' you cannot say that this is fact untill you have sufficient source to back up your claim. also you still fail to answer the OP you are still trying to shoehorn in your opinion of JB's under the floor

Im asking specifically are JB's rated at 30A ok to use on RFC that is covered by a 32A MCB, now try to answer in a focussed manner and please forget about location of JB

 

[Octopus]

now you are just being pedantic, im an electrician not an english teacher, also you can clearly state that under floorboards is not accesible but that is still your interpretation of the regs, untill you name is either 'author of regs' or 'GOD' you cannot say that this is fact untill you have sufficient source to back up your claim. also you still fail to answer the OP you are still trying to shoehorn in your opinion of JB's under the floor

Im asking specifically are JB's rated at 30A ok to use on RFC that is covered by a 32A MCB, now try to answer in a focussed manner and please forget about location of JB

Because clearly a JB, non MF, under a floodboard is not accessible - why would you think it is?

 

[davethsparky]

On that line of thought is a socket behind a built in appliance accessible? Do you fit a socket with maintenance free terminals rather than screw terminals? Do they even exist?

 

[SplitJugular]

Because clearly a JB, non MF, under a floodboard is not accessible - why would you think it is?

you are an absolute joke of a person, im sure you are just trying to wind me up,
and to answer, inaccessible 'to me' means i can not possiblty access that point
accessibly without damage would be a much better way to state this situation in the regs to avoid all this wasted time trying to work out what it means
the regs book becomes more like the bible each day, some people believe in one solid message and wont budge , and the rest see all the contradictory and vauge thigs written whithin

now... Murdoch one last time.... can i have a JOINT (MF or not) above the fuse board in plain sight (in a nicely accessible place just for you) that is rated at 30A, is that 30A joint ok for use on a 32A RFC???

 

[Octopus]

you are an absolute joke of a person, im sure you are just trying to wind me up,
and to answer, inaccessible 'to me' means i can not possiblty access that point
accessibly without damage would be a much better way to state this situation in the regs to avoid all this wasted time trying to work out what it means
the regs book becomes more like the bible each day, some people believe in one solid message and wont budge , and the rest see all the contradictory and vauge thigs written whithin

now... Murdoch one last time.... can i have a JOINT (MF or not) above the fuse board in plain sight (in a nicely accessible place just for you) that is rated at 30A, is that 30A joint ok for use on a 32A RFC???

Just making sure that you realise that under floor boards is NOT accessible.

Next time you are doing fault finding, and you worry there may be a faulty JB under the floor, where exactly will you start cutting up the floor?

 

[SplitJugular]

Because clearly a JB, non MF, under a floodboard is not accessible - why would you think it is?

you are an absolute joke of a person, im sure you are just trying to wind me up,
and to answer, inaccessible 'to me' means i can not possiblty access that point
accessibly without damage would be a much better way to state this situation in the regs to avoid all this wasted time trying to work out what it means
the regs book becomes more like the bible each day, some people believe in one solid message and wont budge , and the rest see all the contradictory and vauge thigs written whithin

now... Murdoch one last time.... can i have a JOINT (MF or not) above the fuse board in plain sight (in a nicely accessible place just for you) that is rated at 30A, is that 30A joint ok for use on a 32A RFC???

 

[Guitarist]

On that line of thought is a socket behind a built in appliance accessible? Do you fit a socket with maintenance free terminals rather than screw terminals? Do they even exist?

Not even in the same ballpark as a JB hidden under a floorboard. I agree with Murdoch, if it's a JB under a floorboard, and is not clearly marked, then it's to all intents and purposes "inaccessible".
As I said earlier, MF kits are cheap, reliable and quick to install. No excuse for not using them nowadays. Any guy who tells you to hide JB's under a floor, rather than using approved MF connections and enclosures does not understand the regs.