Ask an Electrician anything...

[hyphen]

Cold said:

Typical tradie. Promises loads, starts the job then buggers off without completing it.

[944 Man]

ruggedscotty said:

944 Man said:

Why do you always park your vans directly outside the house that you're working on, on new build sites, making it impossible for HGVs to get through?

we dont like to walk.......

Idle and thick is how it comes across.

[pinchmeimdreamin]

PAT64 said:

Hi thanks for the topic, I wish to get a lamp or lighting installed in my attic, how much roughly would an sparky charge for this job ?

£26k

[cayman-black]

pinchmeimdreamin said:

£26k

pmsl....

[ruggedscotty]

dundarach said:

If I have 12v's DC from a Scalextric transformer, how can I step this down inside a model to 5v's DC in a simple component say 1cm without much heat.

So that I can use 5v motors rather than 12v motors, across the power band from the standard Scalextric controllers.

Hugs kisses and thanks

this arrangement would do it - it would step down 12v dc to 5v dc to power your motor and it would be regulated. Would need to have a heat sink on it... but it should do

[ruggedscotty]

phumy said:

Whats the average Day Rate for a sparkie?

dont do contracting.... maintenance spark... 50k a year

[ruggedscotty]

eltawater said:

What's the worst thing you've seen which has prompted you to declare "No f**king way am I touching that" ?

A chiller panel that had been bastardised by a previous incumbert. needed rework to make is safe again. too many cables not dressed properly and a chance of a short that could have been accross 415v 400A incommer tails

[ruggedscotty]

LostM135idriver said:

Baldchap said:

ruggedscotty said:

Electricity - its a flow of molecular matter. dc it flows around a circuit. ac it vibrates in a circuit.

Isn't it the flow of electrons, i.e. subatomic particles?

Yes

In quantum mechanics, the concept of a point particle is complicated by the Heisenberg uncertainty principle, because even an elementary particle, with no internal structure, occupies a nonzero volume. Therefore, electrons have mass and volume, hence electrons are matter.

[ruggedscotty]

LostM135idriver said:

What do you find most satisfying in your work?

Getting the job done well and it looking neat and tidy. oh and it works !

[ruggedscotty]

Countdown said:

If you could start all over again would you still choose to be an electrician?

yes

[Riley Blue]

Serious question time: what could trip the switch in our meter box?

Our electricity went off yesterday afternoon. Neighbours unaffected, our consumer unit checked out all OK so we phoned our supplier who advised an engineer would be with us within three and a half hours. Yes, you've guessed it, no one turned up so we phoned the 105 out of hours emergency number, got through to a different company from our supplier who went through a check list that involved opening the meter box, our own supplier hadn't done this.

Within a couple of minutes I'd done as they instructed and flicked the switch to restore power.

Fast forward to this morning and our supplier phoned to follow up the engineer's visit. Then they said they'd phone back within ten minutes to find out why he hadn't called - they never did. They did, however agree that as the consumer, I shouldn't need to be touching anything in the meter box.

So back to my original question; what could have caused it and is it likely to happen again?

[ruggedscotty]

toasty said:

Do you smoke rollies?

nope dont smoke...

[PugwasHDJ80]

Had a house completely rewired by a reputable firm

have one room here the bulbs in the uplighters and the downlighters have a seriously reduced lifespan- i can't remember the name of the downlighter, but they are £150/luminaire LED jobby- we have 6 and we've lost at least one a year.

The led uplighters have never properly worked- bulbs last no longer than 6 months.

What could possibly be wrong?

[ruggedscotty]

Wheelbrace said:

Do you know the difference between God and an electrician?

there is nio difference, well maybe an electrician wears better clothes ;-)

[ruggedscotty]

steve-V8s said:

A Sparky question rather than one about your van.

Can I, within the regs somehow mix PME and an earth stake ? The previous house had a nice big earth stake where the current one is PME. I have some equipment which is sensitive to supply noise and some which generates RF earth currents. The PME earth, where probably electrically safe has a far higher impedance at high frequencies and is less than ideal. With an earth stake system it was possible to whack in an additional stake local to the equipment and all was well.

Plainly with PME that would be unwise as my stake could end up being the earth for a fault in the neighbour's house and if I separate the two earths the chassis of my equipment could be at a different potential to other things nearby.

Why PME is now preferred is a mystery to me, I can perhaps see it for a block of flats but not for individual dwellings, presumably it is cheaper to install but I can't see any way it is actually better. There are now so many cheap plug in power supplies in use, all adding noise to the supply which you can't filter out without a good low impedance local earth.

mains earths are a black art. and as you rightly point out your seeing some issues with current loops. The mass of the earth you have to take as zero - now if you have an earth spike and that connects to your equipment you will get a current flow to earth if there is any current flowing to earth in your equipment. its about watching the equipment and ensuring that you cut down on those current loops and that should address the problem.

PME is prefered as it ensures that there are multiple points on the neutral that are grounded instead of one. this means that on a longer run the neutral is kept close to earth at as many different points. does that help ? if not i can try and find some more info for you.

[ruggedscotty]

MK1RS Bruce said:

How do you connect the cable between the consumer unit and the meter, there doesn't seem to be anyway to isolate the top of the meter to make such connections in mine.

The meter has a fused cutout at the service hear. This is board property and is usually sealed. The tails from the meter to the consumer unit are now being fitted with an isolator switch to allow isolation of the installation. I see this in more and more places.

[ruggedscotty]

Countdown said:

How easy is it to bypass the meter?

Asking for a friend.....................

seen it done - not really that easy... and can be a major fire hazard

[ruggedscotty]

zetec said:

Have you ever stuck your finger in a plug socket to make your hair stand on end?

no only a vandegraf will make your har stand on end

[ruggedscotty]

stressfree said:

Hi, we bought a new build house and asked to install the outside socket. Socket is installed as a spur from the inside. My concern is that there is no isolating switch inside for the outside socket (water ingress or fault will be tripping an internal rcd on the same ring or someone can steal the electricity when we are not at home). Should they have installed the isolating switch or a separate rcd in the consumer unit? What is required by the regulations?

thank you

regulations dont really state anything about a switch - its probably (If I had done it) tapped off your ring main. If you are concerned about someone stealing npower get your sparkie to come back and put a fuse switch inside the house controlling the outside socket.

The socket will be on the RCD or protected by an RCD (thats in the 18th edition 30mA RCD protection required)

[ruggedscotty]

steve-V8s said:

brman said:

I am also curious what equipment you have that cannot filter the noise locally?

It is mostly very sensitive radio equipment where I am trying to detect and measure fractions of microvolts. As a stating point you need a clean earth to reference the signal against, also you need a very clean incoming power supply for the measuring equipment ideally not using a switch mode supply. A good way of ditching incoming noise on the supply is a common mode choke which passes the filtered noise to ground. With PME the earth has so much noise on it that the filter actually increases the noise floor rather than reducing it. Running the equipment from batteries removes the noise but is not ideal. Other than converting the entire house, or working in the shed, the only solution I can come up with is to use a big isolation transformer so the supply is now floating with reference to the rest on the house and then connect to a local stake just to the isolated equipment.

A better solution would be to stop the import of all the horrible, cheap plug in chargers, laptop power supplies, and general junk which seem to be provided with almost everything. If your phone charger is very small and light it is almost certainly wasting a fair bit of energy making electrical noise rather than charging the phone.

Ah more information.... the right answer to this is that you needed to have a dedicated supply for your equipment. Full galvanic isolation from the mains and thats achieved by a transformer. You will need to configure the primary of that transformer to ensure that what you connect behaves as if its being supplied by a normal UK supply. That means a 30mA RCD and an earth stake with a ground brought back and grounded to the neutral of the secondary. How much load are you needing to supply ?