Soldered joint on ring main-legal?

[alex28]

I have joined 3x2.5mm cables on a ring main by soldering and heatshrink/tape behind plasterboard-is this ok or do I need to use a junction box? have used a 200W soldering iron so they are good solid joints

 

[PrenticeBoyofDerry]

Where joints are not easily accessible, they should be terminated/jointed using either soldered or crimped.
So providing the joint is strong and insulated correctly, you have done the right thing with the joint.

 

[holmslaw]

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[alex28]

surely soldering must be a better connexion than a mechanical joint?

 

[holmslaw]

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[ban-all-sheds]

526.2 does not say that soldering is unacceptable.

 

[bernardgreen]

surely soldering must be a better connexion than a mechanical joint?

No... a soldered joint is not as good as a mechanical joint unless considerable care is taken to ensure there was enough area of direct contact between the two conductors ( copper to copper ) to carry the majority of the current before the joint was soldered.

Wrap and solder where the wrap is the mechanical joint with current passing through copper to copper and the solder is only the securing mechanism ( as is the clamp screw in a terminal ) is normally OK but two conductors laid side by side with the solder carrying the current is not OK and will eventually fail as molecules migrate between solder and copper conductor.

 

[PrenticeBoyofDerry]

For those that are interested
http://www.hse.gov.uk/lau/lacs/18-1.htm

 

[roberta1000]

I've seen both crimps and solder connections fail in service. Personally I generally use solder joints and I would say that whatever the quality of the underlying mechanical connection a properly made solder joint is unlikely to fail. The probability of electromigration failure at the current density of a ring main and the cross section of a sensible solder joint is negligable. (Even with no copper to copper contact at all the resistance of the solder fillet would be as near to nothing as to disregard but it is still poor practice.)

 

[holmslaw]

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[londonboy]

Where those 3 cables meet cant you cut a socket/box and blank plate into the plasterboard and do away with the concealed joint?

 

[holmslaw]

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[flameport]

To solder two solid wires together:

Strip about 2 inches of insulation from the end of each wire
Place the bare copper sections parallel to each other
Wrap thin copper wire tightly around the two wires to bind them together
Apply heat to the joint
Apply solder to flow over the entire joint filling any gaps
Remove heat
When cool, cover with shrinkwrap.

A 100W soldering gun will do for smaller wires (up to 2.5 or 4mm), for anything larger, a gas flame will be required.
Use tin/lead solder with a flux core.

 

[holmslaw]

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[ban-all-sheds]

To solder two solid wires together:

Strip about 2 inches of insulation from the end of each wire
Place the bare copper sections parallel to each other
Wrap thin copper wire tightly around the two wires to bind them together
Apply heat to the joint
Apply solder to flow over the entire joint filling any gaps
Remove heat
When cool, cover with shrinkwrap.

http://www.markhellerelectric.com/solder.pdf