's plan underfloor heating relay tripping rcd

[DirtyDog368]

Hello All

I'm currently wiring up an underfloor heating manifold to an s plan system.
the heating boiler takes its power off a ring main in a new loft.
All circuits in the split consumer unit are RCD protected.
I'm following the wiring diagram given in honey well wiring booklet ed 16. Page 14.
I'm using a relay which is.situated in the consumer unit.

The problem is the relay trips the RCD.

What are my options for wiring in the UFH manifold without tripping the RCDS.?

Thanks so much for your time.
Cheers
DD368

 

[Darkwood]

What is the coil voltage of the relay and are you sure if 230v that you have taken the N to the correct N bar in the CU, have you also done any tests and what results, and have you tried operating the relay without any switching loads connected?

 

[DirtyDog368]

I have completed all tests and for the new circuit and all pass. Insulation resistance OK. Zsok, polarity etc.
I am not entirely familiar with these relays how ever I do believe I have wired it up correctly.
I.e.
A signal wire from system comes to relay and then to neutral activating coil which allow power to travel from consumer unit through the relay and to the boiler to tell it to fire up.

I think that the way the power travels is tripping the RCD.
The relay is a 20amp and I was told by the staff at CEF that was the smallest available. It's an IMO hc20-20 20amp
Cheers

 

[Leesparkykent]

I have completed all tests and for the new circuit and all pass. Insulation resistance OK. Zsok, polarity etc.
I am not entirely familiar with these relays how ever I do believe I have wired it up correctly.
I.e.
A signal wire from system comes to relay and then to neutral activating coil which allow power to travel from consumer unit through the relay and to the boiler to tell it to fire up.

I think that the way the power travels is tripping the RCD.
The relay is a 20amp and I was told by the staff at CEF that was the smallest available. It's an IMO hc20-20 20amp
Cheers

How comes you have a relay in the consumer unit? Is the relay for the UH pump?

 

[davesparks]

What is the relay doing?
It sounds like it's either switching a fault into the circuit or it's linking two circuits together when it is energised.

Where have you taken the supply for the coil from? And where does the supply for the switch side of the relay come from?

 

[pjeffrey]

Have you found a solution? It does seem like you must have wired something up incorrectly, the circuit is pretty straight forward.

 

[Jimmyb]

are you saying you are using the neutral to activate the coil ?

 

[DirtyDog368]

I'd like to post a pic of the wiring diagram. Where are the instructions?

 

[Deleted member 26818]

Does the neutral from the relay go to the same neutral bar as the RFC that feeds the boiler?

 

[Leesparkykent]

I'd like to post a pic of the wiring diagram. Where are the instructions?

This diagram?

 

[Leesparkykent]

This is the contactor you have. It would be helpful if you tell us how you've connected it up.

 

[DirtyDog368]

Ah ha! Yes and yes.
So the
...orange wire going to the relay goes to A1,
And I have a neutral going from A2 to the neutral bar in the consumer unit.
Then I have a live taken from the ring main mcb going to relay position 1 and finally
a cable going from relay position 2 to position 10 on the wiring strip.

I have checked and have used the same neutral bar associated with the ring main from which the boiler takes its power.

Thanks again for your time.

 

[davesparks]

Call an electrician to make that safe ASAP, it is dangerous if it is wired as you have described it and you have obviously missed some very basic concepts of electrical safety

 

[danf1966]

what system is underfloor ? has it got own wiring centre ?

 

[Leesparkykent]

Sorry dirtydog368, I agree with Davesparks #13. I think you need to get someone in maybe with a little more experience..

 

[DirtyDog368]

Don't worry fellas. The system is made safe.

 

[DirtyDog368]

The heating g system does gave it's own wiring centre. How ever the power supply cones from the FRM to the lift were the boiler is.