Junction box accessibility - Tightening screws - how often?

[braychurchmouse]

Apparently the regs say that junction boxes with screw connectors should remain accessible for maintenance (ie not buried under floorboards or loft insulation) because over time the copper wires deform and the screws need to be tightened up. That seems to make sense to me because I've found several times a flickering light problem was traced back to a loose screw in a junction box. In the past I've muttered something on the lines of ..."bl**dy electrician never tightened it up properly". But maybe all is forgiven and they were tight at installation time but became loose over time?

So my question in view of this is ...How often should one go round and tighten them all up? And should we do the same to all sockets, spur boxes etc.?

And the next question is ...Do you think the vast armies of loft insulation installers that Mr Brown is encouraging, will think to reposition all those loft junction boxes to maintain accessibility? .

 

[sm1thson]

So my question in view of this is ...How often should one go round and tighten them all up? And should we do the same to all sockets, spur boxes etc.?.

good question, I dont know how long, but i would say sockets etc need doing. when i moved into my house a couple of years back i went round and tighten everything (it was rewired in 2001), they all needed doing and the one that was most worryingly loose was the washing machine (and previous occupiers had a tumble drier in there also)

And the next question is ...Do you think the vast armies of loft insulation installers that Mr Brown is encouraging, will think to reposition all those loft junction boxes to maintain accessibility? .

I worry more about them covering shower cables and halogen lights. A friends had an installer (grant provided) that certainly didnt care, he found out when a halogen exploded shortly after so he went to investigate further!

 

[ban-all-sheds]

So my question in view of this is ...How often should one go round and tighten them all up?

 

[jlacd]

WTF's that then?

 

[ericmark]

The fact that screws do come lose has been a problem in industry for some time. Service sequels requiring the terminals to be checked have resulted in the wires being necked off and causing just as many breakdowns as leaving them alone. The use of boot lace ferrules does help but these do not work very well with single core cables.
The amount of vibration will have an effect on how long one can leave it between service intervals and the results of one service have to effect intervals in that if no lose screws are found the time is increased and if a number are found the time is decreased. Torque screw drivers are the only real way to stop the necking off problem and the only firm I have seen use them is BT. In the home only guide we have is the recommended time interval between periodic inspection and testing is 10 years or change of occupant.
As to second question not only access but overheating is a problem. I have for some time tried to follow beams unlikely to be covered with insulation and the installers are suppose to also avoid covering cables but with many of the new drives encouraged by the government there seems to be a lack of though on how each individual drive will interact with other items the best example in the compact florescent lamp CFL often referred to as energy saving. This has mercury in it costs more to produce in both resources and transport are in the main not made in UK and by time one brings into the calculations the extra heat that has to be provided by the central heating system it is uncertain if they save any energy. They do reduce maintenance but there is also the problem of epileptic and stroboscopic effects of non electronic types and EMC problems with electronic types. Added to this is as we increase the amount of renewable electrical energy and compare this to heating with is in the main gas and as yet has no renewable content then in years to come to reduce energy we may need to reverse and start using tungsten instead of discharge lighting and as industry has already done start using the lights to also heat the building.
Back in 1970’s MANWEB now Scottish Power build a state of the art building just outside Chester where the whole building was heated by the lights. It was so good it has now been demolished and replaced by a B&Q warehouse.
Returning to your first question there has been a move to get rid of the ring main. This again is all related because of the amount of discharge lighting the volt drop for lighting circuits has be reduced to 3% and since the lighting and power have been separated power has increased to 5% this has increased the amount of cable we can use in a ring main to 80 meters add to this the lower current carrying capacity due to being in insulated walls 2.5mm² cable may only be able to carry 20 amp against the 27 amp it could carry clipped direct. Plus lifting the overcurrent from 30 to 32 amp all added together originally if three sockets were within the first 10 meters and all had maximum current draw the ring main could be overloaded. Now we are looking at first 30 meters and we can get an overload and only real cure is the 20 amp radial.
All best Eric

 

[braychurchmouse]

Thanks Eric...a lot of food for thought there! Re overtightening...I've often wondered if that was possible and its interesting you should mention it. I've got into the habit of using a narrow handled screwdriver when doing up screws in junction boxes etc so that I can't put too much torque on the screw, yet have a good feel for the tightness.

Any thoughts on "maintenance free" junction boxes eg Ashley J803? Not sure how they work but presumably without screws somehow.

BTW I think ban-all-sheds was suggesting Aralditing the screws???

Cheers.

 

[GaryMo]

Araldite?

 

[braychurchmouse]

...or some sort of poxy resin...

 

[ericmark]

I have noted that much of the imported equipment from Germany now comes with the spring type connectors for the control wires but as the cable sizes increase they revert back to screw driver, Alan key, and spanner connections.
One big problem I had was with copper covered Aluminum buss bars where the bars seemed to compress with temperature change and the cables were getting loose at first the electricians were blamed and it did take some time to work out what was happening.
We were originally unaware the core of the buss bar was Aluminum and when we realized this we tried changing for solid copper which cured the problem.
Eric

 

[ban-all-sheds]

BTW I think ban-all-sheds was suggesting Aralditing the screws???

Why " "?

526.3 (ii)

 

[FingRinal]

So my question in view of this is ...How often should one go round and tighten them all up? And should we do the same to all sockets, spur boxes etc.?

132.12(ii) ; 341.1; Chapter 62

And the next question is ...Do you think the vast armies of loft insulation installers that Mr Brown is encouraging, will think to reposition all those loft junction boxes to maintain accessibility? .

Not a chance. They'll have 10 houses a day to do and it will be piece-work.

If the cables have been clipped correctly, there shouldn't be too much to worry about for most. For 'Robin Hood' installs, it might be different.

526.3 (ii)

526.3 (ii) is not a complete answer. It also requires such things as 133.1; 133.2; 134.1 for example.

 

[ban-all-sheds]

526.3 (ii) is not a complete answer. It also requires such things as 133.1; 133.2; 134.1 for example.

Well I wasn't entirely serious that people should use potting compound in JBs, but..

133.1 - the product is tested according to BS 2782, 5664, 874, IEC 243, 250 & 93 to prove its suitability as a potting compound

133.2 - ditto.

134.1 - it might not be good workmanship to fill JBs with epoxy resin - those who come after you may resent you for it.

 

[FingRinal]

BAS,

are we to assume that other answers of yours are not to be taken seriously?