board fed from time clock

[king_11]

Hi I have been asked to put in a 7 way board 6 16 16 16 16 16 16. Each circuit could pull around 13 amps apart from 6 amp obviously. But the customer wants the whole thing pp. a time clock so I've been to the wholesalers and they have suggested i switch it though 2 24 amp contractors via timeclock is this right?

 

[Knobhead]

Why two contactors? Just get a single contactor of the correct rating. Simple and probably cheaper.

 

[Guest111]

Why two contactors? Just get a single contactor of the correct rating. Simple and probably cheaper.

sounds like he is trying to switch the individual circuits not the whole board.

 

[king_11]

Because I'd need a 80 amp contactor? IM trying to switch whole board

 

[Knobhead]

It’s bad practice to split the load between two switches, contactors or whatever. If one contactor fails the other is then overloaded. Do the job properly. You could use a smaller 3 phase contactor as shown. There’s no reason to switch the neutral.

View attachment 11572

 

[telectrix]

sorry, tony, but i preferred you old avatar. where do you pull out such fine drawings so quick?

 

[Knobhead]

Hmm, it looks like one of those awful condoms you buy in a club after a drunken night out. Think I’ll change it back.

The drawing are done in AutoSketch and PhotoShop

 

[king_11]

This has come from Wylex technical office so its gotta be right? Where is the time clock in your pic

 

[malcolmsanford]

Can we assume that these 2 X 24amp contactors ( that is a strange rating) are 3/4 pole and are going to be installed after the MCBs on the load side of the CU ?

Then if that is the case you will need a control circuit for the contactor coil(s). Which voltage contactor coil are you going to use 230volt I assume?

So instead of getting a 7 way CU, get an 8 way and on that spare way fit another 6amp MCB which will be your control circuit.

From the CU take a LINE from that 8th MCB/NEUTRAL/CPC to your time clock supply. From the n/o side of the clock take the LINE to A1 on 1st contactor and parallel to A1 on the 2nd and then NEUTRAL to A2 on 1st contactor and parallel again to A2 on 2nd

 

[Knobhead]

Sort it out your self.

 

[king_11]

its a 4 pole yeah, ok so the new 6amp will control both the contactors?

this is the contactor i was recommened

http://www.******************/Products/WYMESB24.html

2 x24 is still only 50 amp and there is a possiblty of the circiuts pulling 80...is this still okay?

 

[king_11]

Sort it out your self.

thanks

 

[malcolmsanford]

Each pole of that contactor is capable of taking 24 amps each, so your 7 x 16 amp circuits will be going through 7 poles each capable of taking a 24 amp load, so they are fine

 

[Guitarist]

You don't need 2 contactors, just fit an auxiliary block on top and you can control all from 1.
I'm assuming this is for storage heaters. If so, why not just ask the DNO to fit a timeclock to switch the new board?

 

[Knobhead]

Ask Wylex where to fit the timer.

Or do as Guitarist sugests. That way it will be done right.