Programmer live in and live out reversed

xnescx · Dec 17, 2018

hey, I’m a gas safe plumber and today I came across a programmer wired backwards basically, the live in and live out mixed up yet the boiler was still functioning without issue, calling for heat as should.

Anyone care to educate me on the issue with the above or does it not really matter?

buzzlightyear · Dec 17, 2018

No way how did that happen ,are you saying the neutral was in the line and the line was in the neutral reversed polarity.

xnescx · Dec 17, 2018

So normally open and normally closed switch wires where mixed up,

L and N feed was correct, just the switch wires not, I went to replace the programmer for a more user friendly one for my customer hence noticing

xnescx · Dec 17, 2018

buzzlightyear said:
No way how did that happen ,are you saying the neutral was in the line and the line was in the neutral reversed polarity.

So normally open and normally closed switch wires where mixed up,

L and N feed was correct, just the switch wires not, I went to replace the programmer for a more user friendly one for my customer hence noticing

suffolkspark · Dec 18, 2018

The out should have been in the normally open, if it wasnt then surely it was on when it should have been off?

telectrix · Dec 18, 2018

think OP means that S/L was in C and L in N/O, instead of tother way round.

suffolkspark · Dec 18, 2018

Thats what i thought in post 1 but in post 3 he clarified it was NO and NC mixed

Wilko · Dec 18, 2018

Hi - the N is connected to Earth at the supply transformer and the house copper pipework is also bonded to the house's main earth terminal. So any reversals of L and N within the boiler, programmer or zone valves would normally result in it not working, perhaps with a bang. If I've understood correctly, since it was working, the system was likely configured as "volt free" like the diagram, where it's job is to provide a time/temperature controlled connection across the boiler start terminals (B and A here).

[ElectriciansForums.net] Programmer live in and live out reversed

PEG · Dec 18, 2018

So in effect,not wired to conventional pattern,but no risk or harm done.

This would depend on the type of C -N/O-N/C switching fitted,where if there were any additions,such as tell-tale LED's,or other feature,the position of the L and S/L would be crucial.