what switch and how to wire it?

[FrankBlack]

Hi,

I'm new to the forum and very little knowledge of electrics. I need a switch that will allow me to change between 240v sources as follows:

1. 5Kw generator
2. 600W pure sine wave inverter (from 12volts to 240v)
3. an off position

I need to identify the type of switch and what amperage rating I should have. And also how to wire it.

I'm grateful for anyone's help or advice.

Thanks.

 

[ricicle]

very little knowledge of electrics.

Please, for the safety of people and property, use an electrician or educate yourself thoroughly on the subject you are about to undertake. A forum can guide you but not spoon feed it to you.

 

[OwainDIYer]

Hi,

I'm new to the forum and very little knowledge of electrics. I need a switch that will allow me to change between 240v sources as follows:

1. 5Kw generator
2. 600W pure sine wave inverter (from 12volts to 240v)
3. an off position

I need to identify the type of switch and what amperage rating I should have. And also how to wire it.

I'm grateful for anyone's help or advice.

Thanks.

How are you going to handle load shedding so the 5kW load isn't connected to the 500W inverter?

 

[FrankBlack]

Hi,

I'm new to the forum and very little knowledge of electrics. I need a switch that will allow me to change between 240v sources as follows:

1. 5Kw generator
2. 600W pure sine wave inverter (from 12volts to 240v)
3. an off position

I need to identify the type of switch and what amperage rating I should have. And also how to wire it.

I'm grateful for anyone's help or advice.

Thanks.

How are you going to handle load shedding so the 5kW load isn't connected to the 500W inverter?

No idea mate. What would you suggest?

 

[SimonH2]

How are you going to handle load shedding so the 5kW load isn't connected to the 500W inverter?

My guess is manually.
Just a hunch, but I reckon he has some small loads and wants to run off battery for those. But then occasionally he wants to run a larger load, so fire up the genny to run it (and recharge the battery ?)


For the OP, he's probably looking at an industrial rotary switch with appropriate housing, glanding for the cables, etc.
As an example, see the "T" range from Klockner Moeller. Size T0 is possibly marginal, so might need T3.
On Page 7 you'll find switches with "Changeover contact with 0 position" and you'll want switch T0-2-8211/... (or T3-2-8211/...). To complete the part number (the "..." in the codes above), you need to turn to Page 3/4 where you'll find options for enclosure and actuator types - I think you'll want ".../I2" for a plain surface mount switch (but I'm not certain on that).
So you'd be looking for T3-2-8211/I2.

But be warned, such switches don't come cheap !
There may be other/better options - it might help if you gave a bit more detail on how/where this is to be used.

As for how to wire it, my assessment from how you asked the question would be that you should get someone competent to do it for you. Get it wrong and you can damage equipment and/or have a system that allows plugs to have live pins when not powered from a socket. Having bare live pins is considered "a bad thing".

 

[SimonH2]

How are you going to handle load shedding so the 5kW load isn't connected to the 500W inverter?

No idea mate. What would you suggest?

Well that confirms my initial assessment - you should get someone competent to wire the system for you.

One way you could do it would be to use a 3 pole switch. One pole is for the neutral, a second pole switches the light loads between inverter and genny, the third pole connects the heavy loads to the genny but not the inverter.

 

[FrankBlack]

Thanks for all that Simon.

I'd been looking at this type of switch: http://www.ebay.co.uk/itm/110897814137?var=410117576007. Would this do? How about the amp rating?

The application would be basically an off-grid solar set up providing 12 volts for most of my needs, with the inverter for occasional small appliance use. The generator would be a back up for occasional use of the same small appliances or occasional power tools. I just need a convenient, panel mounted switching method really.

 

[bernardgreen]

I'd been looking at this type of switch: http://www.ebay.co.uk/itm/110897814137?var=410117576007. Would this do?

NO because that is an isolator.. 3 or 4 ON OFF switches that operate together.

You need a centre off 2 pole 3 way change over switch.

Please heed the advice given that you ask an electrician experienced in this type of work to design and construct the change over system for you.

Also be wary of items being sold on internet auction sites. Not all are genuine and some fakes can be extremely dangerous.

 

[OwainDIYer]

An experienced electrician familiar with this type of system will probably follow wiring diagrams similar to
http://www.smartgauge.co.uk/nb_ac_sys.html
You also need to take great care over isolating and fusing the battery side which will be high current and can cause severe burns and fire.
http://www.smartgauge.co.uk/whereiso.html

You could start by contacting some of the suppliers and installers listed at
http://www.smartgauge.co.uk/wheretobuy.html

 

[FrankBlack]

I'd been looking at this type of switch: http://www.ebay.co.uk/itm/110897814137?var=410117576007. Would this do?

NO because that is an isolator.. 3 or 4 ON OFF switches that operate together.

You need a centre off 2 pole 3 way change over switch.

Thank you

 

[FrankBlack]

An experienced electrician familiar with this type of system will probably follow wiring diagrams similar to
http://www.smartgauge.co.uk/nb_ac_sys.html
You also need to take great care over isolating and fusing the battery side which will be high current and can cause severe burns and fire.
http://www.smartgauge.co.uk/whereiso.html

You could start by contacting some of the suppliers and installers listed at
http://www.smartgauge.co.uk/wheretobuy.html[/QUOTE]

Thank you for the links. I'll certainly seek the advice of an electrician. I'm just trying to educate myself beforehand so that I know the type of switch to buy and how it all works in theory.

 

[ban-all-sheds]

I'll certainly seek the advice of an electrician.

You need an electrician to do it.

I'm just trying to educate myself beforehand so that I know the type of switch to buy and how it all works in theory.

Let the electrician supply all of the parts needed.

 

[SimonH2]

Just to expand on the comment I made earlier about damaging equipment or having live exposed plug pins (also echoed in the Smartgauge page linked to).

The switch chosen must have positive contact opening, and I think (I'm sure someone will correct me if I'm wrong) the normal requirement for safety switches is for a contact separation of 3mm minimum.

The industrial cam switches generally meet these requirements (but read the small print in the technical docs), but some cheaper switches don't. A good switch has a cam action that pushes the contacts apart - the positive opening bit.

Some switches close the contacts by cam action, and use spring pressure to open them - with these it's possible for the contacts to weld closed and stay closed when you move the switch to another position. It should be fairly obvious that this is "a bad thing". Ditto many toggle and rocker switches that only ever move the contacts (open or closed) by spring pressure.
I'm thinking that there are probably toggle or rocker switches that have the required current capacity and switching function (at significantly lower cost) - but many of them won't meet the requirements to make it safe.

Again, a competent electrician should be aware of these sorts of issues - though I suspect a few (perhaps the ones that only do domestic, and have only ever done domestic) may find it outside their knowledge.