Inverter 3pin 240v dc plug to consumer unit.. can this be done?

[jrthwaites]

Hi,

ive recently set up a solar system with a charge controller & 24v battery system to inverter. Which converts it to 240v - it has a 3pin uk plug on the inverter which powers uk devices. I want to run lights & possibly a ring main on it if poss? What’s the best way to connect the inverter to a consumer unit via the 3 pin. Is it possible? I’m very new to this / winging it
TIA

 

[Kannon Fodda]

First the obligatory safety warning as you say you are "winging it" that 240V electrics can kill. If you don't know what you are doing you really should get it done by a professional.

In practice, most motorhomes have lighting and other power kit running at 12V. Running lights at mains voltage incurs the inefficiencies of the inverter. You normally only use mains power off grid in a motorhome for heavy large things that can't be done on 12V such as microwaves, hairdryers and similar (if you really need them) and then you are probably looking at decent 2000W level inverters or greater.

You don't say the size / power of the inverter. You suggest a "ring main" but it's not clear if there would be enough power (amperage) from the 240V inverter output to cope, but in practice a three pin socket outlet on the inverter, equivalent to a mains wall socket, does 13Amp max (at least that is the biggest fuse you can have in the plug).

It would be a bodge and unusual, but in theory you can wire your 13A plug to suitable flexible lead, and take the cable to the inlet fuse of your consumer unit (fuseboard). You then wire your circuits again with flexible leads, to the fused outlets to the consumer unit. In some respects you consider the consumer unit and it's subsequent circuits as a big extension lead, and we all know that many of the multigang extension leads are frowned upon for their potential to overload.

Big challenges will be to ensure the powered 240V circuits have adequate earthing and other safety cut off such as RCD. Not that easy to achieve in a motorhome when you actually don't have an earth.

You can get switchgear to enable you to swap from mains hook up (EHU) to the inverter output and vice-versa. That adds a whole extra level of complexity and it can be simpler to keep your inverter output and EHU circuits entirely separate. For me I have a single 240V output from a small 375W rated inverter (used for a powerful laptop or recharge of an e-bike battery) kept entirely separate to the 12V power that does lighting, water pump, 12V TV, USB socket, with the 12V charged from engine or solar or mains change if on hook up. There is an entirely separate 240V socket outlet system for hook up use to a small ring circuit of 13A outlets (but few campsite will give you more than 16A, and most only 10A so you still have to watch your overall use).

 

[dunnah01]

I just put these connectors in the 240v supply, one from ehu other from inverter output and swap over to suit on or off grid.

 

[laurieash]

Could you use a small extension with a 13 amp plug on each end.
One into your Inverter and the other into a socket on the van.

Not a sparky so don't no if it's viable.
Just seen dealerships with extensions plugged into just the sockets not into the Huck up point.

 

[Googlebot]

I have just done that. Works a treat and using an auto changeover means no thinking about it.

The link to the thread is in my signature.

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[Googlebot]

Could you use a small extension with a 13 amp plug on each end.
One into your Inverter and the other into a socket on the van.

Not a sparky so don't no if it's viable.
Just seen dealerships with extensions plugged into just the sockets not into the Huck up point.

That is a recipe for death.

I would never ever do that.

 

[autorouter]

Could you use a small extension with a 13 amp plug on each end.
One into your Inverter and the other into a socket on the van.

Not a sparky so don't no if it's viable.

Let's be clear about this. That is something you should never do under any circumstances. Potentially lethal.

There are proper ways to connect an inverter, that will connect the sockets. Either just to the inverter, manually/automatically switching between hookup and inverter. You'd want an extra RCB and a double-pole MCB, or an RCBO. If you don't know what that means, you need to do further research until you do.

 

[Bessy765]

By putting a 13 amp plug at each end of an extension lead you will leave live pins exposed. This is why the live is a female socket and requires a male to plug in to it as the male plug with exposed pins is never live.

 

[Bessy765]

Also if you just connect the inverter directly to the vans 240 volt circuit, you may end up powering the battery charger that’s charging the batteries the powering the inverter (makes you dizzy just thinking about it. For safeties sake consult an electrician familiar with motorhome electrics

 

[Raul]

Could you use a small extension with a 13 amp plug on each end.
One into your Inverter and the other into a socket on the van.

Not a sparky so don't no if it's viable.
Just seen dealerships with extensions plugged into just the sockets not into the Huck up point.

There is a term for this set up. It’s called a suicide lead. Sometimes used in off grid from generator. Not for everyday use, and should not be done for obvious reasons.

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[autorouter]

What’s the best way to connect the inverter to a consumer unit via the 3 pin. Is it possible? I’m very new to this / winging it

To answer the question, use a changeover switch (manual) or a changeover relay (automatic). A changeover switch swaps the COMMON connections between CONNECTION1 and CONNECTION2.

CA20A211/GBA001E | Kraus & Naimer, DP 3 Position Double Throw Cam Switch, 20A | RS

uk.rs-online.com

Inverter loads are the loads you want to run from the inverter, like the sockets. Non-inverter loads are the loads you definitely don't want to run from the inverter, like the water heater element, the battery charger or maybe the fridge.

Connect the Inverter loads to the COMMON of the changeover switch. Connect the inverter output to CONNECTION1, and a wire from the consumer unit to connect hookup power to CONNECTION2.

You can't just use any old changeover switch. You need a 'break-before-make' type, which definitely disconnects one side before it connects the other side. Some of them have an OFF position in between the two other positions.

Here's some of the things you need to think about. Quite a lot at first, but remember that plenty of people have connected up an inverter, in a motorhome, yacht or canal barge, and everything works fine.

Don't connect the battery charger to the inverter - the battery powers the inverter, the charger tries to charge the battery with power from the inverter, it's obviously a bad idea.

High power loads for more than short bursts will drain the battery quickly. Water heater mains elements, fan heater, even a 3-way fridge on mains power will drain the batteries. Use gas or diesel for these instead. However high power in short bursts is OK: microwave, hair dryer etc.

Low power loads like phone and laptop chargers will work fine from the inverter, but the problem is a high-power inverter may have quite a high self-consumption. For example a 10 watt phone charger might result in 20W of self-consumption, which is very inefficient, especially if left on overnight.

You also need to think about protection devices. An RCD protects against electric shock. An MCB protects against overcurrent. An RCBO is a device that does both. Using an RCBO on the inverter output is a good idea.

 

[gus-lopez]

Could you use a small extension with a 13 amp plug on each end.
One into your Inverter and the other into a socket on the van.

Not a sparky so don't no if it's viable.
Just seen dealerships with extensions plugged into just the sockets not into the Huck up point.

If they are they should be shut down.lift up the external EHU flap ,touch the pins and You'll be dead.

 

[pappajohn]

Sorry to be blunt...... You're having to ask so it's not a job for you to do.
Get a qualified motorhome technician or sparky to do it

 

[cargom]

Sorry to be blunt...... You're having to ask so it's not a job for you to do.
Get a qualified motorhome technician or sparky to do it

Hi yes i would get a sparky to do it

 

[Stealaway]

I simply took a 2.5 mm flex from the 1000watt inverter socket to a separate new twin 13a socket to supply the TV and sound bar. I have just installed a further one from this into the garage for an a electric charger. Maximum load will be either the size of the inverter or the 10amp fuse in the inverter plug.

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[gpat]

I think it contravenes the electricity act as what would happen if you accidentally plugged your van into the mains hook up