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Sir Sparks
Sir Sparks, President/Owner/ Master Electrician
Category: Electrical
Satisfied Customers: 2532
Experience:  US State Certified & UK Electrical Contractor for all electrical fields/disciplines
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I have purchased a Drayton Ivenseys SM1 Timer switch to replace

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I have purchased a Drayton Ivenseys SM1 Timer switch to replace my malfunctioning timer switch of a different make which was over twenty odd years old. My problem is the old switch only had four terminals which was straight forward while the SM1 has six. I have two cables to connect both of two core with red & black insulation. I presume the supply cable goes to N & L of which the red is live. The other cable I do not know how to connect.The red is also live. All combinations I have tried blow the 3amp fuse. I thought it would just be a combination of disconnecting the old and connecting the new.
Can you please help me?
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Sir Sparks :

Hi, Expert Sir Sparks here. I am a qualified USA Master & UK Electrician as well as many years world wide experience. I will do my best to help.n I will check to see if I can find the wiring diagram on line. You are correct that N will be neutral and L will be Live power in.

OK the answer will depend on where your second set of black/red go (and what they do), It would help if you could tell me this. Anyway if the output is just a NO Voltage switch then use Terminal 1 and terminal 2. If it requires to be a switched 240 volt output then Black of second wire to neutral N (together with other black too) Red (of second wire) to terminal 2. Red supply to L and finally a link wire from L to terminal 1.

Edited by Sir Sparks on 10/5/2010 at 3:08 PM EST
If as you say that BOTH Reds are hot then it would appear that you need my first option (No link wire). To test this out temporarily simply connect that second set of black and red (not the 240 volt feeds) together and the heating should function. If it does not work either the stat is now fried or you need to connect it as in the second option.
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Customer: replied 7 years ago.
I have tried both those options but the boiler still fails to ignite. At least the fuse did not blow. One of the cables must link with the room thermostat in some way. However the boiler was able to ignite with the thermostat turned off before the old switch gave up. The thermostat only enabled the pump to swich on. Hope you can give further consideration to my problem please. thankyou

If you have tried it both ways it is possible the timer or themostat is now burned out.


Are you saying that when you tried my advice (both wiring ways) the boliler did not ignite? but the fuse did not blow?


Also where is the blowing fuse located?

Edited by Sir Sparks on 10/5/2010 at 6:36 PM EST