automated distribution board

[Steve]

i got a phone call last night, from work. The warehouse lights had gone out. I told the girl on the phone to check all the "switches" on the "fuse box" (language she understood) were "facing the same way". She said they were, so i sez "well ill have a look when i get in tomorrow".

I looked this morning, sure enough, no MCB had tripped. Odd, i thought, then i looked at the markings, and realised there is actually no MCB for warehouse lights. Or shop floor lights . . . .

Turns out we have a board with turning switches for shop lights, warehouse lights, boiler, etc, with settings for on, off and auto. It has a timer, and is supplied with a C63 3phase supply. Inside is full of relays and MCBs etc. I opened it up and found the MCB that had tripped.

Result: warehouse lights now working, turns out a double flourescent fitting had blown, taking the lot out with it.

My question is this: should i actually be opening this box (it has a key, like a gas box)? All the switches are on the outside, but there are exposed neutral bars and earth bars inside. I would say i should be able to do it myself, since it contains MCBs which may need to be reset, as this morning. Then again, i am exposing conductive parts (and live terminals) by doing this. I also had to study a wiring schematic for the box, to discover which MCB to reset, since they are merely labelled by number. I wasn't going to call an electrician just to reset an MCB which i can do myself. Any comments?

 

[Spark123]

My question is this: should i actually be opening this box (it has a key, like a gas box)? All the switches are on the outside, but there are exposed neutral bars and earth bars inside.

The fact it has a key to open it makes it compliant with the regs as only skilled persons should have access. If access is required with the panel live it should (by todays standards) have internal screens / barriers to impede direct contact to live parts.

I would say i should be able to do it myself, since it contains MCBs which may need to be reset, as this morning. Then again, i am exposing conductive parts (and live terminals) by doing this. I also had to study a wiring schematic for the box, to discover which MCB to reset, since they are merely labelled by number. I wasn't going to call an electrician just to reset an MCB which i can do myself. Any comments?

Are you formally trained and deemed competent to carry out this task? If not and something goes wrong causing you to injure yourself or others you are leaving yourself wide open to prosecution or even worse. I know it sounds a bit daft for only resetting an MCB, but with the way the country is at present (blame culture), I wouldn't be putting my neck on the line for anyone.

 

[Steve]

I'm resetting an MCB, what could possibly go wrong? I might electrocute myself . . its happened before, it may well happen again. Nobody else will get hurt, im not going to get sued. And if i called our store support service and they sent their usual electrician, he would only show me what to do if it happened again, and its not unknown for them to leave us spare fluorescent tubes on bulb-changing visits.

I think the design of this panel leaves it wide open to criticism. MCBs are supposed to be accessible, yes? Why have them "locked" (key is left on top of the unit) away with live parts??? IMO, they should be mounted far enough forward that they protrude from the front of the panel (like a CU) so opening the panel up is not nessecary.

Having said that, i fully respect the guy who wired it up, it is a VERY neat install.

EDIT: and its sunday, no electrician till tomorrow, toilet lights had gone too, on same cct, i had to do something. Didn't have a lot of choice, staff complaining at me all the freakin time.

 

[pdcelec]

An mcb tripping is an "effect". Why it tripped is the "cause". The cause needs to be dealt with and not the effect. If you are not deemed competent to do the job, then the company is at fault for not employing someone competent. If ever anything happened to you (or anyone else,) the company could be sued and the company could sue you for doing this task. Would you employ a plumber to change the brakes on your car? Would you go to PC world to buy a galllon of oil?

 

[plugwash]

if it happens repeatedly and there is no obvious cause (like bulbs blowing) then i agree it needs to be looked into but does anyone really do a full inspection every time they reset a bloody breaker?!

 

[pdcelec]

Yes

 

[andy]

if it happens repeatedly and there is no obvious cause (like bulbs blowing) then i agree it needs to be looked into but does anyone really do a full inspection every time they reset a b****y breaker?!

only if it keeps trippin. if its just a 1 off then just switch it back on

 

[ban-all-sheds]

I might electrocute myself . . its happened before

It's a miracle!

Crafty lives!!

 

[Steve]

I might electrocute myself . . its happened before

It's a miracle!

Crafty lives!!

yes ban, my dad left some wires hanging off a wall (pre part p) and turned the circuit back on. I brushed past it and zzzzz for about 3 seconds. 32A ring main. MCB didnt trip.Another time, i smashed a live fairy light while pushing it in (ooi, what current and volt exists in a 20-series fairy light kit at each lampholder?)

I knew the cause of the mcb tripping, that fluorescent light was flickering the day before and had obviously failed bringing the whole circuit down (a C10 too, must have been spectacular). I know what im doing, im not going to touch a live busbar or anything. Badly designed equipment.

And the company will employ the most expensive electrician they can find in Manchester and send them to Sheffield, you know the sort of thing, they never try and find anyone local. I thought id save them a couple of hundred quid and do it myself.

 

[Spark123]

my dad left some wires hanging off a wall (pre part p) and turned the circuit back on. I brushed past it and zzzzz for about 3 seconds. 32A ring main. MCB didnt trip.

An MCB is an overcurrent protection device, to get it to trip it requires over 32A which is well above the 0.25A limit which can cause death:

Another time, i smashed a live fairy light while pushing it in (ooi, what current and volt exists in a 20-series fairy light kit at each lampholder?)

One of the good uses I have found for a powertracer, use it to find where the last live lamp in the run is, unplug and change the dud lamp, easy and you don't need to leave them plugged in.

I knew the cause of the mcb tripping, that fluorescent light was flickering the day before and had obviously failed bringing the whole circuit down (a C10 too, must have been spectacular).

Are you 100% sure it was though? How did you prove this? Did you repair or isolate the broken fitting before re-energizing? Where is the minor works cert?

I know what im doing,

Can you prove that you know what you are doing? Do you have any formal qualifications? Did you have permission from your supervisor to do carry out these works?

And the company will employ the most expensive electrician they can find in Manchester and send them to Sheffield, you know the sort of thing, they never try and find anyone local. I thought id save them a couple of hundred quid and do it myself.

Is your life / livelihood worth more than a few hundred quid?

 

[andy]

Are you 100% sure it was though? How did you prove this? Did you repair or isolate the broken fitting before re-energizing? Where is the minor works cert?

you come home/ switch the light on and it blows, tripping the lighting circuit. what do you do? go and switch it on again and replace failed bulb?

or fully test everything and issue a minor works cert to say the light has been changed properly?

so, since im 99% sure you do #1 and not #2, shut the **** up

 

[Spark123]

We are not talking home, we are talking commercial / industrial, which are covered by the Electricity at Work Regs, the Health and Safety at Work Act and the PUWER to name a few. It doesn't sound like you have much industrial background Andrew, hence maybe it should be you doing the shutting up.

 

[Adam_151]

yes ban, my dad left some wires hanging off a wall (pre part p) and turned the circuit back on. I brushed past it and zzzzz for about 3 seconds. 32A ring main. MCB didnt trip.

Wouldn't expect it to, MCBS offer little or no direct contact protection

Another time, i smashed a live fairy light while pushing it in (ooi, what current and volt exists in a 20-series fairy light kit at each lampholder?)

across the contacts - 12v , between a contact and ground - it depends where on the string it was, anything between 0v and 240v is possible, current will be whatever current the volatage is able to push through you, which depends on conditions

(a C10 too, must have been spectacular).

Not necessarly, the mcb will switch itself with nothing more than a 'pop' not like a fuse, where it has to burn out a bit of wire (even a 3ph C63 will just quietly switch itself off), the only thing that could have been spectactor, is the part that failed

(mcbs that have become welded closed are another matter tho, think lec saw one that was in need of sweeping up off the floor! )

 

[andy]

We are not talking home, we are talking commercial/industrial.

so? do we really need an electrician to reset a MCB?

if i spill some water, do i really need to go find a clearner to deal with it?

 

[Spark123]

We are not talking home, we are talking commercial/industrial.

so? do we really need an electrician to reset a MCB?

Who said anything about an electrician, a suitably trained and authorised person will surfice.

if i spill some water, do i really need to go find a clearner to deal with it?

Only if you don't feel your training has covered you to do the task safely.