20a DP switch for light

[still learning.]

hi, would it be a no no if I was to use a 20a DP switch for a light,

the reason for using it is they want a light putting in a cupboard in a childs bedroom and a light switch with a light on it to indicate if the cupboard light has been left on and this is the only type of switch i can find.

I just was wondering if this was acceptable or if it went against the regs?

 

[Short Circuit]

cant see a problem with that, as long as you are taking it from the lighting circuit. If you are coming from another circuit, you could always use a switched FCU with an indicator on, its doing the same job.

 

[gpz900jim]

it will be ok, but you will also need a neutral to power the led. if you dont have a neutral, it wont light up, also, check that the switch box is deep enough as you dont want the wires squashing

 

[still learning.]

so if i take the power from the last light in the circuit down to the switch and then to the light that will be ok.

 

[Adam W]

No problem with that at all. Alternatively you could use a grid switch and grid neon configuration, which might be less cumbersome.
I'm pretty sure you don't need a neutral for a neon.

 

[gamblor6]

you do need a neutral for a neon. i have a dimmer sw that has no neutral but the small light on it still works, witchcraft i think lol

 

[Adam W]

Do you mean you don't?
Like those horrible neon screwdrivers - you only need a live, and a conductive body for the lamp to light.

 

[Amp David]

Can't they tell that if the switch is down then the light is on lol

 

[gamblor6]

the neon in a 20a dp needs a neutral. this dimmer is called a reactive dimmer, or summit. no idea how it works. someone on here.ll tell me no doubt

 

[still learning.]

when i have istalled the new light do i have to test the whole circuit or just what i have installed?

 

[Deleted member 26818]

Just what you have installed.

 

[telectrix]

the neon on a switch with no neutral works when the switch is in the off position. the idea is to be able to locate the switch in the dark. it works because it's wired across L and S/L, and sees the S/L as a neutral untill the switch is made.

 

[Amp David]

Thought that when doing a MWC you were to test the circuit you have modified, not just your new bit.

Section 3 on the MWC is titled, INSPECTION AND TESTING OF THE MODIFIED CIRCUIT AND RELATED PARTS. to me this means all of it[FONT=Calibri, Arial, Helvetica, sans-serif]https://www.parcel2go.com/dhl-parce...ml_dhltrackingalert&type=email&location=email[/FONT]

 

[gamblor6]

id say all the circuit needs tested. you need to be sure the circuit is fit for purpose.

 

[Hawk81]

No problem with that at all. Alternatively you could use a grid switch and grid neon configuration, which might be less cumbersome.
I'm pretty sure you don't need a neutral for a neon.

In a 20amp double pole switch a neutral is needed for the neon

 

[Deleted member 26818]

Thought that when doing a MWC you were to test the circuit you have modified, not just your new bit.

Section 3 on the MWC is titled, INSPECTION AND TESTING OF THE MODIFIED CIRCUIT AND RELATED PARTS. to me this means all of it[FONT=Calibri, Arial, Helvetica, sans-serif]https://www.parcel2go.com/dhl-parce...ml_dhltrackingalert&type=email&location=email[/FONT]

It doesn't state such on the model forms in BS7671.
There are 4/5 essential tests listed that should be caried out, some of them will include the existing part of the circuit.
Such as earth continuity, IR and perhaps if applicable an RCD test.
Now if you want to check Zs, polarity correct etc. at each point on the circuit, please do so, just be aware that it is not a requirement of BS7671 to do so.

 

[Amp David]

Would never normally do Zs at every point anyhow. But would be doing all others, on the old and new part of the circuit.

 

[Short Circuit]

you will need to test the full circuit mate, and complete a minor works certificate

 

[Deleted member 26818]

Would never normally do Zs at every point anyhow. But would be doing all others, on the old and new part of the circuit.

So where would you do Zs at then?
What other tests would you do?

 

[Amp David]

So where would you do Zs at then?

Highest R1 R2 point

What other tests would you do?

Everything it asks for on the minor works.

I must be missing something here

 

[Deleted member 26818]

Yes you must be.
I asked you where you would test Zs, and you have stated at the highest R1+R2 point.
What about at the point where you have conducted the work? How would you determine where the highest R1+R2 point is?
The MWC asks for earth continuity, IR, Zs and polarity, but you have stated that you would not do Zs?
Make your mind up, either you would conduct a Zs test at each point or you wouldn't.
Recently I was asked to install a light in someones porch.
Simple matter as the CU was on the other side of the wall from where the light was to be positioned.
Run a feed from the downstairs lighting MCB to the fitting and then a switched line from there to the 2 gang light switch in the hall which was replaced with a 3 gang switch.
Should I then go to their downstairs bath room at the rear of the house, and drop out all the down lighters out of the newly decorated ceiling to establish which has the highest R1+R2 and then test the Zs?
How would that establish that the wiring I had installed had earth continuity, correct polarity and acceptable Zs?

 

[Amp David]

Never once stated I wouldn't do a Zs test.

With your litle porch light you'd of tested R1 R2, and proved polarity. Your Zs would be taken fronm furthest point on the circuit, might be the porch might not.