I know nothing about contactors.....

[Jonny66]

Contactors.....(and lots of other things)

Was hijacking a thread so thought I'd start my own......please feel free to take the pee:drool5:
By the way, this isn't for a job I've got lined up, it's just one of the many things I know very little about but would like to learn,

So, wiring and use of contactors, ......... in say lighting circuit,

why are they used in general? is it simply so that a smaller conductor can be used to energise the coil?

How would they be wired up in a lighting circuit ? I know they can be used for large banks of fluros but have never used one....so would they be wired thus.........say 6amp MCB line to switch then switch line & N to contactor coil.....then say 20amp MCB circuit (L/N/CPC) to contactor top and out to lights at bottom?


Will the contactor deal with in-rush currents at start up and allow B type circuit protection or would the in-rush still need to be taken into account when selecting circuit protective devices?

Don't suppose contactors take kindly to 500v, so does this need to be taken into account when IR testing? and

can contactors add considerable impedance to a circuit when Zs testing, like RCDs sometime do?

I know there are lots of different types of contactor, but just looking for some general info and guidance

Cheers
Jon

 

[telectrix]

i on ly learned last week that the earth is not flat and the sun doesn't orbit the earth.

 

[Jonny66]

Ah ha, I knew that, what I did was, I drew a very large triangle (with equal sides) in the Mohabi Desert and realised that all the angles only added up to 178.984 degrees thus proving the earth is sort of round .....

 

[KevinS]

- I only found out yesterday that having your van sign written can deduct on your insurance (albeit slightly), i never knew that, and was never asked when i got my current insurance, something to bare in mind next time.

Did you also know
1) your car/van insurance is no cheaper if you say you keep it in the garage overnight.
2) your house insurance is no cheaper if you state you have a burglar alarm. But then they may refuse to pay out if you are burgled and the alarm wasn't on. ALWAYS STATE YOU HAVE NO BURGLAR ALARM

 

[markc123]

Did you also know
1) your car/van insurance is no cheaper if you say you keep it in the garage overnight.
2) your house insurance is no cheaper if you state you have a burglar alarm. But then they may refuse to pay out if you are burgled and the alarm wasn't on. ALWAYS STATE YOU HAVE NO BURGLAR ALARM

Lost my mobile phone on a night out last year, mobile insurance said and i kid you not..........that because you lost it in a public place you aren't eligible for a new phone....i checked the contract which i hadn't read (foolishly) and it did state that, it also stated that if you're vehicle was broken into and your mobile was stolen the insurance was void, and also it was void if you handed your mobile to someone and they damaged it.........................leaving literally the only possible way to claim is if you lose it in your own home, but they still require a police reference ID. Yes, im just as confused, i cancelled the policy the same day.

Lesson - do NOT get your mobile insurance with the Halifax.

 

[Rockingit]

Contactors still have a place in domestic, as well. For example more complex heating systems with multiple zone valves or using the signal wire from interlinked smoke alarms to open electric security gates for the fire service and so on. I had to build a custom 3 contactor box to enable a whole-house extract unit to be triggered from 3 different lighting circuits as the neutrals needed to be kept apart to stop the RCD's from tripping, and so on.

 

[Wonderwall]

One down side to keep in mind regarding contactors , is that if you lose power on the coil circuit , you lose all lighting,( or whatever you are controlling)
i.e. if you have lights spread over 3 phases and the building loses a phase, you could potentially lose all lighting as oppose to only a third

 

[T&Earth]

Jonny 66

I'm glad you asked about this I'm not sure about these as well read all the answers still scratching my head a bit! I like to see drawings / diagrams with an example. Telectix could make a mint by putting all this down in a book. The combined knowledge on this forum must be staggering.

Thanks 4 answering our questions and thanks for your patience
Many Thanks
T&E

 

[Geoffsd]

And you can use a CH thermostat/programmer to regulate your electric heating.

 

[Jonny66]

Hey I've still got so much to ask, just never get round to it...I think to grasp alot of these things you need to do some of your own research and just keep reading, it goes in eventually.

I've often wondered about that myself, the book thing that is, theres alot of guys on here who could make a fortune putting some of this info into print.......dosnt seem to be alot of real life type books around on electrical installation....

 

[Rockingit]

Jonny 66

The combined knowledge on this forum must be staggering.

Yes, it is, and no matter how many years ago it was since I was sat in college and under the ever-watchful eye of my old chief as a lad, I still learn something everyday. I think if this place was fantasy football then it would be pointless to even hold the FA cup, the winner would be a forgone conclusion.

 

[Rockingit]

....dosnt seem to be alot of real life type books around on electrical installation....

There are some good ones around, I'm told a certain Mr Scaddan has made a decent income from writing, but ultimately being a spark is all about getting your hands dirty - there's no book can tell you how to wrestle with a cable or how best to position yourself when you need three hands above your head, nor can it tell how to how to pull a floorboard or fit a hospital saddle....that's why doing your time (apprenticeship) is SO important rather than just dumping some very limited theory into your brain on a short course.

For example, if I say 'Fleming - left or right?'......how many 'sparks' on here actually know what I'm referring to? Yet it's an electrical fundamental, just ask Tony why!

 

[Jonny66]

Could be "generator" right hand, "motor" left:wink5: