replacing of mcb in board

[salmo]

is it safe enough to just switch off mcb you want to change and removing this from busbar using insulated driver as there is no current flowing through mcb.Thanks for any info

 

[bernardgreen]

NO it is NOT safe.

The bus bar will be live ( 230 volts ) and if you touch it then a possibly fatal current will flow through you if there is any route to ground or neutral via your body.

 

[BS3036]

No, you must turn off the main switch. Why do you want to change the mcb? To be honest, if you need to ask the question, you may be about to do somethng stupid, so please let us know what its all about.

I see bernard' s replied too. Take it to heart!

 

[bongos]

What is wrong with the existing MCB? They can go faulty but regular tripping could indicate a problem with the circuit.

If you are changing the rating of the exisiting MCB then you must confirm cable sizes, fittings etc are up to spec and test that the EFLI is within the regs. In a domestic setting changing the rating of the MCB would be notifiable.

 

[Spark123]

There is usually a bus bar shroud with a label which says "ISOLATE SUPPLY before removing" or something similar.
What if you touched something to earth on a TN there would be a big bang with from a few hundred amps to a few thousand amps flowing and the only upstream protection normally the DNO fuse.
You could liven up all the ECPs in the property too, if the supply is TT.

 

[martinxxxxxx]

No you cannot.

Surely you jest!

You cannot be serious!

Is this someone pulling our chain?

Don't touch anything in there it is illegal for you to do anything in the fuseboard. Based upon your lack of competency with electricity. More than that you are not safe from yourself.

Do a bit more research than posting a question here if you are stubborn enough to still want to go ahead. Please.

Martin

 

[sparkydude]

Admittedly martin its not a good idea to be trying to change the mcb in the fuseboard unless you have the required level of competency. However it is NOT illegal to touch anything in the fuseboard and by making such a statement is misleading. Just wanted to clear that up .

Nick

 

[salmo]

NO it is NOT safe.

Thanks bernardgreen.The reason i was asking for is that i was watching a friend replace an mcb in his board and all he did was switch off the mcb he wanted to change then he removed the live brown cable from top of mcb then unscrewed the mcb from busbar removed it then put new one in and tightened this one up then put brown cable back in tightened this up then switched mcb back on and was ok.Was this ok.

 

[wingcoax]

Is your friend a qualified sparky? Even then and using heavy duty rubber gloves it would be dodgy. That said you SHOULD switch off at the mains.

 

[salmo]

Is your friend a qualified sparky? Even then and using heavy duty rubber gloves it would be dodgy. That said you SHOULD switch off at the mains.

Thanks for reply Wingcoax spoke to him about this and although he is not qualified he says he does this all the time as working on premises that they have to leave supply on ie shops etc.He says that as long as the mcb is switched off then no load and touching of busbar with insulated driver you will not get shock , but he did say you have to be very carefull.

 

[kai]

You could possibly do it if you have a Crabtree "starbreaker" board, or a Square-D "Quickline" board, as their MCB breakers have a pin at the back of the breaker, which plugs straight onto the shielded busbar.

 

[Spark123]

Is your friend a qualified sparky? Even then and using heavy duty rubber gloves it would be dodgy. That said you SHOULD switch off at the mains.

Thanks for reply Wingcoax spoke to him about this and although he is not qualified he says he does this all the time as working on premises that they have to leave supply on ie shops etc.He says that as long as the mcb is switched off then no load and touching of busbar with insulated driver you will not get shock , but he did say you have to be very carefull.

Very dodgy work practice and I'd imagine the HSE would take a very dim view should he have an accident or "monkey see monkey do" has an accident, for the sake of switching off for 5 mins.

 

[Lectrician]

In a domestic install you have little excuse for not isolating, but in commercial applications, this will be done on a daily basis. All sparks who work in commercial installations are guilty of doing this.

Some people have no respect for the dangers, and it is these people that are at danger when doing this sort of thing.

 

[bongos]

spoke to him about this and although he is not qualified he says he does this all the time as working on premises that they have to leave supply on ie shops etc.He says that as long as the mcb is switched off then no load and touching of busbar with insulated driver you will not get shock , but he did say you have to be very carefull.

I've seen it done like this but it really shouldn't be. There is no excuse either. If the supply to the customer has to be isolated then so be it. This should have been made clear to the customer before the work started.

I think this would be in breach of Electricity at Work Regulations also and if you did this working for a firm then possibly they could get rid of you for such a breach (I don't know though!)

Interestingly, is the reason you asked that you didn't feel comfortable with his methods yourself?

 

[salmo]

[Thanks bongos but yes i thought this was bad practice but wanted the opinions of good electricians out there,Cheers