MCB used as light switch

[wallyanker]

Hello Guys/Gals

I was called out to a shop yesterday to look at a faulty heater. Whilst I was there, I noticed that to turn the 3 rows of 8 foot fluorescent lights off, the shop staff use the 16a mcb's in the fuse box, 1 mcb per row. My understanding from the regs book is that a mcb should not be used for functional switching. Can someone confirm I have read this correct?

Thanks
Pete

 

[mogga]

yes you have it correct larger stores use timeclocks or BMS systems via contactors to turn lightin on not MCBs

 

[wallyanker]

Thanks mogga, I'm gonna go back and fit light switches for each row. Think there is 4 double 8 footers per row so was thinking of fitting a 3 gang light switch.

Thanks again

 

[ian.settle1]

Thanks mogga, I'm gonna go back and fit light switches for each row. Think there is 4 double 8 footers per row so was thinking of fitting a 3 gang light switch.

Thanks again

You might suggest replacing the fittings as well as it is going to be hard getting 8' lamps in the future.

 

[mogga]

yea that would be an idea as 8fts are going out oif production and stock is hard to come by and will run out soon

 

[Darkwood]

Where in the regs does it state mcb's cant be used for functional switching?, most modern mcb's have a switching capability (mechanical life) in the hundreds of thousands, also i would check the wiring complies as 16amp would be pushing the bounderies for even a 1.5m^2, so check if its cable calcs comply or is it wired in 2.5mm^2.

 

[SirKit Breaker]

MCB is an acceptable form of switching.

 

[Sparky Ninja]

Just confirm SirKit Breaker there, Table 53.2 states a circuit breaker (be it BS EN 60898, BE EN 60947-2 or BS EN 61009-1) are all acceptable to be used as functional switching.

 

[wallyanker]

Thank you to all for the information. It just doesnt seem right that opening a cupboard, flipping down the front of the consumer unit and flicking the 16a mcb off is an acceptable way of turning the lights on and off.
I'm going to fit normal light switches anyway for convienence and because I think it is the proper way to do it, I don't think the shop assistant girls should be turning mcb's on and off every day.

 

[Darkwood]

Thank you to all for the information. It just doesnt seem right that opening a cupboard, flipping down the front of the consumer unit and flicking the 16a mcb off is an acceptable way of turning the lights on and off.
I'm going to fit normal light switches anyway for convienence and because I think it is the proper way to do it, I don't think the shop assistant girls should be turning mcb's on and off every day.

Well its your call but i think its just the way you are thinking that deters you from using mcb's to switch, if you actually think about it the mcb (60898 i suspect) is more robust and durable than the light switch you intend to put in, and a light switch would only be required if their is a health and safety risk of trying to get to the mcb in the dark to turn the lights on and in this case putting remote switching in is justifiable.

 

[Sparky Ninja]

In some ways its not acceptable. You just have to trim the fat to find the right reason. Stating that you simply cant use the MCB is incorrect as the regs can prove. However you could maybe consider the use of the installation with regards to the competency of the user. You could find reason, depending on the layout to suggest that only skilled persons should be able to 'avoid dangers that electricity may create', which regular access to the CU may introduce.
There could be other things to consider like access etc also....

 

[tlangdon12]

There is also a risk to the business if there are other circuits in the fuse box, e.g. what if someone's hand slips and they accidentally switch off a circuit, possibly not even realising they have done this. Or accidentally turn on a circuit they didn't intend to.

 

[Ponty Massive]

I remember years ago, not sure if it's the same these days, but we installed "Police lighting" direct from the MCB. These light's were designed not to be switched off at night, but perminently left on. From memory, the design showed one row in four would not be switched off. Could this be the same sort of thing??

 

[malcolmsanford]

If I remeber rightly and I may be wrong wasn't the old BS 3781 not able to be used for functional switching

 

[mogga]

Had a recent em light test where every fitting failed after 10-15mins then lassie told me she was told to turn off mcb to put all lights out as switches only turned out some the ones left on were the Police lights which had a key switch but them being bean stackers just thought leaving lights on all night was burning money

 

[Jas0n7]

in the tick box section of a nic peroidic form one of them says something along the lines of devices selected being used what they we're designed for. a breaker of any form is a proctective decive and not a switch!

 

[Sintra]

But still can be used for functional switching according to the brb.

 

[jaresquire]

You see it all the time, and in the absence of a centralized switch bank it is obviously easier. I have replaced zillions of fire and intruder batteries ruined by full discharge because the supply was turned off in this way.

 

[Adam W]

Why exactly do the staff do that?
Is the main switch/contactor faulty?

I too don't think it seems right for unskilled persons to be poking around in the consumer unit, apart from anything because they could accidently turn off something they shouldn't, or realise the main switch can save turning off 4 breakers without realising it turns off the freezer (or all the freezers if it's a frozen food shop).

 

[malcolmsanford]

This is another of these good practice issues. The bare facts are that according to table 53.2 a MCB can be used as a functional switch.

That makes about 80% of sparks cringe but it is widely used in retail outlets. I sub contracted quite a few outlets on a shopping centre near me and I reckon out of about 8 units I did 5 of them controlled the lights this way.

I spoke to the main contractor about this and asked why you couldn't put a fish key in, or a timer in or a bank of switches somewhere that customers could not get to and as a prank turn the lights off.

He told me the main reason was cost, if you worked out the amount of shops that a large retail organisation have then to run Switch Lines in every shop would increase the construction costs quite a bit. This is why most large Mega type shops now don't have false ceilings. You go into a Tesco Extra you will see all the air condition trunking, the Sparks cable tray, the plumbing pipes, it looks half finished but it is all to do with costs.