Another Sparks Magazine comp question!

[Simonslimline]

Just seen another question for this weeks competition from sparks magazine to win a Megger socket tester. The question reads.....

Which of the following is not an isolating device?

a) Single pole light switch
b) Double pole switch
c) Plug and socket
d) Triple pole isolator


Seems everyone is putting C. plug & socket as the answer. I have had a look at table 53.4 in the BGB and plug & socket - outlets say suitable for isolation. I just wondered what anyone's thoughts on this are. Am i looking at this wrong (probably).

Thanks

 

[telectrix]

answer is #a. a single pole light switch is a functional switch, not an isolator.

 

[Simonslimline]

answer is #a. a single pole light switch is a functional switch, not an isolator.

Yeah just realized but not sure which BS number it was.

60669-1 i think.

 

[Silly Sausage]

Agree with A.
Isolator should disconnect ALL Live conductors.

A SP light switch would still leave the N connected at the load.



(I think, without checking!!! )

 

[Simonslimline]

Second on the list for "Switching Device" in Table 53.4 of BS7671

[h=1]BS EN 60669-1
[/h] [h=2] Switches for household and similar fixed-electrical installations. [/h]

Isolation = NO. Emergency switching = Yes. Functional switching = Yes.


I should read my BGB more often and not ask these silly questions to be honest. Cheers

 

[Silly Sausage]

I should read my BGB more often and not ask these silly questions to be honest. Cheers

We'll let you off just this once, seeing as it's the Trainees Section!

 

[happysteve]

Agree with A.
Isolator should disconnect ALL Live conductors.

A SP light switch would still leave the N connected at the load.



(I think, without checking!!! )

I'll let you off on account of your caveat!

"537.2.1.1: Every circuit shall be capable of being isolated from each of the live supply conductors. In a TN-S or TN-C-S system, it is not necessary to isolate or switch the neutral conductor where it is regarded as being reliably connected to Earth by a suitably low impedance."

I read this as: If you're checking a TT system fitted with SP MCBs, then you can't use these for isolation (but they're ok for ADS and functional switching).

But the question arises: should DP MCBs (rather than SP) be used on TT systems?

(also, agree with everyone, "A")

 

[Silly Sausage]

I'll let you off on account of your caveat!

"537.2.1.1: Every circuit..............

Hahaha...Touche!

 

[telectrix]

I'll let you off on account of your caveat!

"537.2.1.1: Every circuit shall be capable of being isolated from each of the live supply conductors. In a TN-S or TN-C-S system, it is not necessary to isolate or switch the neutral conductor where it is regarded as being reliably connected to Earth by a suitably low impedance."

I read this as: If you're checking a TT system fitted with SP MCBs, then you can't use these for isolation (but they're ok for ADS and functional switching).

But the question arises: should DP MCBs (rather than SP) be used on TT systems?

(also, agree with everyone, "A")

for D/P isolation on a TT earthing system you have a D/P main switch ( often a S type RCD.)

 

[happysteve]

for D/P isolation on a TT earthing system you have a D/P main switch ( often a S type RCD.)

Yes you do! You're right, of course.

I was wondering about the implied meaning. If "Every circuit shall be capable of being isolated," does that not mean you should be able to isolate every circuit? And if, in order to isolate a circuit on a TT system, you have to disconnect the N as well as the L, surely that means that you should have devices capable of acting as isolators on every circuit (ie DP MCBs or RCBOs)?

(A simple "no" will suffice; I am also amenable to a certain degree of p!ss-taking for overcomplicating things!)

 

[pennychew]

Second on the list for "Switching Device" in Table 53.4 of BS7671

BS EN 60669-1


Switches for household and similar fixed-electrical installations.



Isolation = NO. Emergency switching = Yes. Functional switching = Yes.


I should read my BGB more often and not ask these silly questions to be honest. Cheers

Post away mate, ive just learned something i didnt know before that i wouldnt have if you hadnt posted it up :icon4:

 

[Paul.M]

Whilst your looking into this subject, take a look at water heaters and local isolation. eg fused spur supplying boiler etc????

 

[GMES]

Second on the list for "Switching Device" in Table 53.4 of BS7671

[h=1]BS EN 60669-1
[/h] [h=2] Switches for household and similar fixed-electrical installations. [/h]

Isolation = NO. Emergency switching = Yes. Functional switching = Yes.


I should read my BGB more often and not ask these silly questions to be honest. Cheers

Slim this is exactly why the trainee section exists so that you guys can ask whatever you want without fear of being mocked.
This goes for all Trainees this is a safe haven for people to learn, do you think all us old farts were born and instantly knew everything.

 

[Guest77]

Agree with Glenn, anything goes in here and no sarcasm at all, your safe haven guys, enjoy this place.

 

[Simonslimline]

Slim this is exactly why the trainee section exists so that you guys can ask whatever you want without fear of being mocked.
This goes for all Trainees this is a safe haven for people to learn, do you think all us old farts were born and instantly knew everything.

This is stuff i have covered in college already. I am finished college and now just need NVQ3 and AM2. Just needed to have another look and get the brain working again as it was a while back.

I would never hesitate to ask any questions in here as the mentors are all sound and what one of us knows another may not so could potentially learn something.

This section has helped me a lot since i joined and is a good laugh.

A big thanks to everyone for there useful input here :shades_smile: