Switching 6kW load with 7 day programmer

[peterhanson]

I need to switch 2No 3kW heaters on using a 7 day heating programmer. Presumably I'll need a contactor to switch that load rather than the heating programmer (?).
Can anyone recommend a suitable one? Many thanks if anyone can help,
Peter

 

[davesparks]

2 x 3 pole contactors rated at 3kw each maybe? Unless of course it's single phase where a 2 pole rated at 3kw would work. Of course that assumes it's just a plain old resistive load.

 

[peterhanson]

2 x 3 pole contactors rated at 3kw each maybe? Unless of course it's single phase where a 2 pole rated at 3kw would work. Of course that assumes it's just a plain old resistive load.

.........
Thanks Dave,- its single phase, so could I use a single 6kW contactor?

 

[davesparks]

.........
Thanks Dave,- its single phase, so could I use a single 6kW contactor?

If you want to yes, but why wouldn't you use one rated for 3KW if that's what the load is?

 

[peterhanson]

The heating load is actually 6kW, provided by 2 No 3kW convector heaters,- so I suppose I could use 2 x 3kW contactors or a single 6kW contactor ,- which I imagine will be cheaper (?)

 

[Leesparkykent]

You can get 3kw contactors for about £16 each

 

[davesparks]

The heating load is actually 6kW, provided by 2 No 3kW convector heaters,- so I suppose I could use 2 x 3kW contactors or a single 6kW contactor ,- which I imagine will be cheaper (?)

Why not just use one contactor rated for 3KW? The smallest you'll likely get off the shelf at a wholesaler is going to be a 20A 2 pole I would have thought so why not go with that? That'll switch 2x single phase circuits

 

[telectrix]

use a 4 pole contactor 2 for the L's and 2 for the N's.

 

[peterhanson]

Thanks telectrix,
So that way I could switch on two heaters with the one contactor with one live and one neutral to each (?)
In your experience would the supply from the programmer to the contactor always be 240V?
Peter

 

[SPARTYKUS]

They can get hot so if you can install it with space around it, all the better. Which might make two 3kW ones better, just depends what make you get, what enclosure they're going in, where its going.....

or Tels idea with space around it

 

[123]

Get a 230v programmer (vast majority are, some need links added some don't) and a 20A contactor with a 230v coil. Sounds like a really simple job tbh

 

[davesparks]

Thanks telectrix,
So that way I could switch on two heaters with the one contactor with one live and one neutral to each (?)
In your experience would the supply from the programmer to the contactor always be 240V?
Peter

You can use a 2 pole contactor to switch both, or you can use a 3, 4, 6 or any number of poles but you'll need 2 as a minimum. Unless there is a particular reason why you need 4 poles that is.

The switched live to the coil will need to be at the rated voltage of the coil.

All these questions are making me wonder whether you are a trainee or a non-electrical tradesman?

 

[Andy78]

Well for definite, he has very limited experience of using contactors. It's a bit late to wonder whether or not he knows what he's doing after he has been given his advice.

 

[davesparks]

Well for definite, he has very limited experience of using contactors. It's a bit late to wonder whether or not he knows what he's doing after he has been given his advice.

I try not to give the answer away too easily in my replies.