R1 + R2 inconsistent readings.
- Thread starter joocedup
- Start date
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I went to wago.com and searched for "approvals"
see if you can find UK wiring. I can't.
http://www.wago.com/cps/rde/xchg/SI.../eng-index.html?fldSearch=approvals&x=11&y=10
see if you can find UK wiring. I can't.
http://www.wago.com/cps/rde/xchg/SI.../eng-index.html?fldSearch=approvals&x=11&y=10
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From the viewpoint of an electronics engineer.
Coonectors which do not have a screw to exert pressure onto the conductor [1] to hold it mechanically and [2] to ensure good contact with the terminal all have to rely on only a spring to provide the pressure that the screw would have provided.
Springs can soften if heated, corrosion on the conductor ( dull copper instead of bright copper ) if not broken by the pressure exerted then will result in a resistive joint. That presents a risk of heating when current flows. Heat, spring softens, joint deteriorates, more heat. Joint fails.
A well designed screwless connector used to join clean bright copper conductors will make a good joint. Whether it can be described as maintainance free will depend on how well it was installed.
Another concern is short duration overloads, A screw terminal with a significant amount of metal will carry a fault current for some seconds until the protective device operates and without the metal mass heating up significantly. On the other hand a contact with only a small amount of metal and hence little thermal mass could suffer rapidly rise in temperature during the overload and thus compromise the joint at that time or, due to spring softening, permanently afterwards.
Connectors of any mechanical sort need to be accessible.
Coonectors which do not have a screw to exert pressure onto the conductor [1] to hold it mechanically and [2] to ensure good contact with the terminal all have to rely on only a spring to provide the pressure that the screw would have provided.
Springs can soften if heated, corrosion on the conductor ( dull copper instead of bright copper ) if not broken by the pressure exerted then will result in a resistive joint. That presents a risk of heating when current flows. Heat, spring softens, joint deteriorates, more heat. Joint fails.
A well designed screwless connector used to join clean bright copper conductors will make a good joint. Whether it can be described as maintainance free will depend on how well it was installed.
Another concern is short duration overloads, A screw terminal with a significant amount of metal will carry a fault current for some seconds until the protective device operates and without the metal mass heating up significantly. On the other hand a contact with only a small amount of metal and hence little thermal mass could suffer rapidly rise in temperature during the overload and thus compromise the joint at that time or, due to spring softening, permanently afterwards.
Connectors of any mechanical sort need to be accessible.
All should read appendix 15 to the 17th.
Wagoboxes are defined as maintainance free; appendix 15 clearly states you can use maintainance free JBs in inaccessible locations.
At the end of the day, if the LABC/NIC inspector is willing to pass them (which they will do) then its within the intent of the regs.
Wagoboxes are defined as maintainance free; appendix 15 clearly states you can use maintainance free JBs in inaccessible locations.
At the end of the day, if the LABC/NIC inspector is willing to pass them (which they will do) then its within the intent of the regs.
who defines, and who tests, and who agrees that a product qualifies as maintenance-free?
(clue: it should not be the manufacturer's marketing department)
Once this has been done, would you expect the manufacturer to proudly display the approval?
(clue: it should not be the manufacturer's marketing department)
Once this has been done, would you expect the manufacturer to proudly display the approval?
http://www.wagobox.com/docs/files/Wagobox_BS7671_Regs.pdf
I ask again, are there any LABC inspectors who will fail this product if installed "maintainance free", or has the NIC issued any warnings about their widespread use in this situation?
No.
So, can we all stop getting our knickers in a twist about a product that is in widespread use in inaccessible areas?
Its not the manufacturers fault that the 17th defined maintainance free without defining what that meant.
Who gives a monkeys what the NIC say on the matter, do you care what the ECA, NAPIT or ELECSA say about them? What qualifies the LABC to make judgements on such matters also?
Junction boxes and twisted taped up wires are also in widespread use in inaccessible areas, but I can't see why people shouldn't express an opinion.
My knickers are fine, how are yours?
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