2 questions...

[Mikey_A]

These are 2 assignment questions that i just cannot answer . Can someone please help....?

1. A mains operated room thermostat requires three conductors to enable it to operate correctly. Can you connect the thermostat to an existing two core and cpc cable?

2. What is the output voltage of an Insulation Resistance Tester which is required to test a 230 volt cirvuit?

Thanks

 

[sparky40]

500v for IR test on 230v.
I believe some stats require three conductors, live neutral, switch line ??whereas others only need two. But the cpc must not be used as a conductor, only as an earth in any case.
Hope this is of some help.

 

[sparky40]

500v dc that is.

 

[Mikey_A]

Thats great Spark40, thanks for your help.

 

[Taylortwocities]

The stat question is to test if you would consider using the cpc of the existing cable as a live conductor. And to that question your answer would be NO.

TTC

 

[Mikey_A]

cheers mate, so in all instances the cpc should NOT be used for anything other than its purpose of a protective conductor?

 

[Taylortwocities]

Too blooming right. All live conductors must be insulated. The cpc (earth) conductor isnt.

TTC

 

[securespark]

I do see the cpc being used as a neutral or a strapper (in both cases in a switch drop), but this is a serious no-no as cutting into a cable part way along its length, you would fully expect the bare conductor to be a cpc and nothing else. I also see three core flex used in timer fans or PIR's using the cpc as a switchwire.

 

[ban-all-sheds]

These are 2 assignment questions that i just cannot answer

Have you been taught this, or are you just expected to know?

1. A mains operated room thermostat requires three conductors to enable it to operate correctly. Can you connect the thermostat to an existing two core and cpc cable?

Yes, you can.

But you may not.

 

[ban-all-sheds]

cheers mate, so in all instances the cpc should NOT be used for anything other than its purpose of a protective conductor?

Have you been bunking off?

 

[Mikey_A]

Have you been bunking off?

I'm very new to this so please be patient with me, i'll get there in the end!!

 

[LionIrons]

Mickey_A, if you were ever in this situation you could use the 2 cores and leave the neutral as it only serves as a return for the heat anticipator that shuts off before the air inside the thermostat actually reaches the set temperature.[/quote]

 

[Softus]

Mickey_A, if you were ever in this situation you could use the 2 cores and leave the neutral as it only serves as a return for the heat anticipator that shuts off before the air inside the thermostat actually reaches the set temperature.

...which means that the thermostat wouldn't work properly.

 

[LightHouseMan]

Drop the set-point down a touch. It'll work.

 

[Pensdown]

With no neutral the stat will have a switching differential of anything up to 6deg....not very useful