Dodgy trade pictures for your amusement! - 1 Million Views!

[littlespark]

Thanks, makes sense makes me think of electronics and Relays etc.

Just another word for a relay.... although contractors are combined relays.... to switch so many poles through one switch.
Also can use a 12v momentary push button to switch and hold in a 400v 3 phase load (like a motor) or as described above, a simple light switch turning on a much higher load than the switch itself could handle

 

[Mark Wright]

Just another word for a relay.... although contractors are combined relays.... to switch so many poles through one switch.
Also can use a 12v momentary push button to switch and hold in a 400v 3 phase load (like a motor) or as described above, a simple light switch turning on a much higher load than the switch itself could handle

I didn't want to go totally off-topic just been trying to get a better understanding of DOL and there always wired in such a way that there latched providing undervoltage protection totally forgot really there just like relays and do what relays do, also never seen them used for anything but DOLs.
Doh..

 

[westward10]

The control circuit for the contactors is a dawn to dusk sensor so when the lighting level drops it switches the contactors on.

 

[Mark Wright]

Wow that's more interesting than your domestic circuit

 

[pc1966]

In a way a relay and a contactor are the same - both use an electromagnet to operate the switch contacts. The difference is more of size and application.

As a general rule "contactors" are high current, say 20A and above, and usually single-throw (i.e. on/off only, but can be 2, 3, 4, etc poles that are simultaneously switched).

Relays come in all sorts of shapes & sizes and are generally low-medium current, so some have gold contacts for "dry" switching of signals in the microvolt / milliamp range, but most have some sort of silver alloy contacts for up to the low tens of amps range. Often relays are available in double-throw (i.e. change-over contact) configurations with commonly 1 or 2, sometimes 3, rarely 4, simultaneous sets of contacts.

Also some relays are magnetically latched so have typically two coils and you momentarily energise one to set it "on" and the other for "off" (but with changeover contacts that is really positions 1 & 2, etc).

 

[davesparks]

As a general rule relays are used in control circuits and contactors are used to switch loads.
Generally contactors provide simple switching with limited or no function beyond a simple make/break when the coil is energized, but they can have current ratings in the hundreds of amps.

Relays can provide all manner of functions for control, protection, sensing, latching, timing etc etc, and generally are rated for lower currents (usually in t

However there is no actual definition or hard and fast rule to what the difference is.
Relays can and do exist with current ratings in the hundreds of amps, and some contactors can incorporate timing or latching functions etc etc.

 

[pc1966]

davesparks raises anther aspect: often the term "relay" is used more generally in electrical engineering (rather than electronics) as a control block element, not just as an electromagnetic switch.

So timers, phase loss protection, etc, are all often described as relays because they switch on something else happening.

 

[telectrix]

i have implanted relays in my head. 4 of them.

1. clicks in when it's time to get up.
2 . clicks in when it's time for bed.
3. tells me when it's time for beer.
4. tells me it's not yet time to die.

i love electronics.

 

[littlespark]

Let’s hope no4 doesn’t get a loose connection

 

[telectrix]

Let’s hope no4 doesn’t get a loose connection

no chance. there are too many people i still got to annoy. anyway, as i see it, i got to survive till 87 to recover all the taxes i've paid for 60 years, through the state pension.

 

[Baddegg]

i have implanted relays in my head. 4 of them.

1. clicks in when it's time to get up.
2 . clicks in when it's time for bed.
3. tells me when it's time for beer.
4. tells me it's not yet time to die.

i love electronics.

Bet it’s a messy day if 1 & 3 get connected arse about face ?

 

[telectrix]

Bet it’s a messy day of 1 & 3 get connected arse about face ?

1. and 3. generally are complimentary.

 

[Simon47]

Contactors are used where you don't want, or can't have, the full load running through a switch, or when multiple circuits need to be switched by a single device.

As in this case where four (?) separate high current loads are being switched by the one photocell. There's two contactors here because the ones used are only 3 pole - there are some with 4 poles, but often the 4th pole is relatively low current and used just for the hold-in circuit.
BTW - you can get a variety of add-ons for many contactors. Auxiliary contacts that clip on the side, delay relays (used to be pneumatic, I suspect some are electronic these days) that clip on the front and can be used for sequencing (e.g. start one motor, after a delay, start the second), interlocks that mechanically prevent two pulling in at the same time (e.g. for reversing or star-delta circuits). There's a lot of things you can do beyond simply switching on and off.

 

[Strima]

Went to price up for remedials today, 3L1 RCBO failed to trip when tested.

Easy enough I'll just replace it, then I saw this on site, no mention of damage to 3L2 and signs of water damage down the right hand side of the board. Luckily just external lighting so no major risk to life...

I think the water tank in the room above had sprung a leak at some point.

 

[littlespark]

Not just our wonderful trade.
Saw this in my neighbours house after
their system boiler changed to a Combi.
I think the extra 15mm’s shooting to the right must be feeding a basin in the bedroom above

Copper pipe comes supplied in straight lines for goodness sake.....

 

[freddo]

looks like they re used old pipework in the new position. I hate seeing plastic push fit fittings on copper pipe, rubbish.

 

[littlespark]

Yes, you can see the old pipe run where the wall hasn’t been painted.

 

[freddo]

Another non electrical seen when installing some heaters:
The 'weld' has completely failed and the bracket is no longer attached to the steel lintel.

 

[SparkySy]

Rough isn't the word! I don't think that could be classed as any sort of weld!

 

[Strima]

That's some proper pigeon poop!!!