I'm having to take on a project of installing a consumer unit, but the socket side has to be on a digital timer, so the sockets go off at night. I haven't found a digital timer of a high enough ampage to just wire in, so may have to use a 4 pole contactor. As I have never done one, can anyone tell me the correct way to wire and install it?
4 pole contactors
- Thread starter DRL
- Start date
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there should be a diagram on the contactor, make sure you buy one with a mains coil.
the contacts of the contactor just act like switches so for single phase you wan't 2 pole (assuming you wan't all poles isolated) and for three phase you wan't 4 pole. You can also use a 4 pole contactor to switch two seperate single phase circuits (or 4 if you only wan't single pole switching) if you so desire.
the coil of the contactor should be fed from the timeswitch which should be fed from a permanent supply (with appropriate overcurrent protection).
i'm guessing this is a commercial environment of some sort and they wan't the sockets off at night in case equipment is left on (or say its somewhere like a museum and they wan't to turn the displays off at night). While certainly a good idea you MUST combine this with no volt trips (if not already present) on any moving machinary so they do not start without warning.
the contacts of the contactor just act like switches so for single phase you wan't 2 pole (assuming you wan't all poles isolated) and for three phase you wan't 4 pole. You can also use a 4 pole contactor to switch two seperate single phase circuits (or 4 if you only wan't single pole switching) if you so desire.
the coil of the contactor should be fed from the timeswitch which should be fed from a permanent supply (with appropriate overcurrent protection).
i'm guessing this is a commercial environment of some sort and they wan't the sockets off at night in case equipment is left on (or say its somewhere like a museum and they wan't to turn the displays off at night). While certainly a good idea you MUST combine this with no volt trips (if not already present) on any moving machinary so they do not start without warning.
It's a community centre, so all that should ever be left in sockets would be 13A plugs for minor accessories. I'm assuming that I'm linking in the contactor like I would the second half of a split load consumer unit?
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DRL said:
Why not feed an entire consumer unit off a large contactor - for internal lights, sockets, appliance circuits etc, and just have the main CU for external security lights and the fire and burglar alarms and EM lights.
A contactor has A1 and A2 terminals - these control the coil, and act as the "load" presented to the timer.
it also has 1 2 3 4 and maybe 5 6 7 8 terminals - these are the switching terminals which you connect the actual switched load to. The diagram on the front shows which terminals are linked. (actual terminal markings may vary)
By the way, a timer in a community centre may not be the best idea - what if an event overruns and they all get plunged into darkness? Surely the caretaker ought to be the person who shuts everything off at night (he still has to come and lock up etc)? I mean, still have the contactor, but control it with a keyswitch by the front door - this might be a better idea.
B
breezer
not to mention if a time switch is used, the time change from GMT to BST
company i used to work for twice a year i had to go and change all time switches for the door entry systems
company i used to work for twice a year i had to go and change all time switches for the door entry systems
Does the building have a burglar alarm? If have a relay connected to the SW+ output on the alarm panel, and use this to control the contactor. When the alarm is set (when the last man leaves the building) the power will switch off. As he re-enters the building next morning the power will come back on.
I have only been given the details for the building verbally, I have yet to visit the site, but there has been no mention of a burglar alarm, though I see that what you are saying makes perfect sense. All the info that i have been given has been based on the requests made by the client.
Are you saying that there si like a switched and non switched side to a conatctor? Does the timer fit on the contactor then? Soory for my ignorance, but gthis is the first time I have come across one.
Are you saying that there si like a switched and non switched side to a conatctor? Does the timer fit on the contactor then? Soory for my ignorance, but gthis is the first time I have come across one.
This is a 40A 4-pole contactor. You wire the timer's switched live to A1 and neutral to A2 so it controls these terminals.
Then wire your controlled circuits to the rest of the terminals, as the diagram shows. To be honest, if you dont understand the diagram on the front, you shouldnt be doing this.
If you're not sure, ask one of your more experienced colleagues to give you a hand and show you how. Are you newly qualified? Are you familiar with commercial work? Contactors are used pretty widely in commercial applications.
B
breezer
novel idea about the alarm, but it may be installed by a professional alrm co.
best go for key switch option, but make sure Fire alarm and burglar alarm do not loose their supply when mains turned off
best go for key switch option, but make sure Fire alarm and burglar alarm do not loose their supply when mains turned off
This is my first commercial project since qualifying, I usually stick to domestic.
If you can hang on until tomorrow, I am going to finish a job I have been doing that is a very similar setup to what you require. It is a contactor controlled by a digital programmer and a room stat which switches 4 x 3kW heaters on and off.
I will take a couple of photo's for you and post them on here.
I will take a couple of photo's for you and post them on here.
By fitting a contactor, does this mean that the digital timer doesn't need to be of as high a Amp rating as the MCBs?
B
breezer
put it this way.
the contactor should be connected by a lower rated fuse, be that its on its own ctt or on the same cct as that that it switches off, (in which case it needs an fcu)
the idea of a conatctor is that it can switch greater loads than it it self uses.
say for the sakeof argument the conatctor switches (as this one can) up to 40A, the coil that operates the contactor my only draw 100 mA (example figure only)
so that means you can use 1mm cable to run to say a hidden light switch.
now the light switch can only switch up to 6A, but by using a contactor in effect the light switch is now switching up to a 40A load
(all though in reality it is only switching the 100mA of the contactor coil)
the contactor should be connected by a lower rated fuse, be that its on its own ctt or on the same cct as that that it switches off, (in which case it needs an fcu)
the idea of a conatctor is that it can switch greater loads than it it self uses.
say for the sakeof argument the conatctor switches (as this one can) up to 40A, the coil that operates the contactor my only draw 100 mA (example figure only)
so that means you can use 1mm cable to run to say a hidden light switch.
now the light switch can only switch up to 6A, but by using a contactor in effect the light switch is now switching up to a 40A load
(all though in reality it is only switching the 100mA of the contactor coil)
The burglar alarm was a very good idea.
My only reservations are
1/ Complacancy may actually encourage folk to leave things plugged in that they`d otherwise remove and also the inadvertant switching on a load might have H & S problems.
I`d definately do a risk assessment and weigh up all the pros and conns
My only reservations are
1/ Complacancy may actually encourage folk to leave things plugged in that they`d otherwise remove and also the inadvertant switching on a load might have H & S problems.
I`d definately do a risk assessment and weigh up all the pros and conns
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