Installing inverter

[UsedtobeGinger]

Hi, seems like a jolly place - are there any electrical experts on here?

I have a self-build Relay, installed ,most electrics about 3 years ago. I put in EHU (with a consumer unit including 2-pole RCD) with a single outlet socket, solar panels, lots of other stuff. I did not put in an inverter, as I didn't really need 230V off-grid for anything.

Anyhow, time moves on and I am working from the van on occasion, and would like to charge my laptop when off-grid, so am looking to install a low power inverter to supply the aforementioned AC outlet socket. As far as I can tell, there are a couple of ways I could do this safely - with the main things being to a) keep the EHU and Inverter AC supplies isolated (I am proposing to use a manual switch) and b) avoid the possibility of my leisure battery charger from being supplied by the Inverter output.

Re the two options in the diagrams attached, does anyone:

1) have any comments on safety issues? - I am not totally sure about avoiding earthing loops and whether / where neutral-earth bonding might be necessary
2) think there would be any other advantages to either option?

Thanks in advance for any constructive comments - including if you point out any howling errors in my diagrams!!

 

[UsedtobeGinger]

Soz, ignore this - see next post with the correct diagrams!

 

[Squiffy]

If you only want the inverter to charge your laptop, then cut out all the hassle and just use a cigar 12volt type socket with a small plug in type 300w inverter ( Pure sinewave, but I've never found it necessary) because that's all you need for any laptop/phone or tablet. That's what I've used (Modified inverter) for over ten years and never had a problem. Phil

 

[UsedtobeGinger]

Thanks Phil. I am quite nervous about a modified sine wave inverter used for a laptop - and a complication is that I consult for a firm who give me one of their laptops to use, so its not just straightforwardly my problem if it goes kaput because of the supply. I looked for a low power plug-in inverter, but none seem to be true sine wave.

 

[Squiffy]

Just as quick search and found this but there are many more.

https://share.google/N1SFGgvyNXsPwNuoW

Phil.

 

[trevskoda]

A inverter to charge a laptop is over the top, many do this but as above a cigy charger which ups the voltage is cheap and simple, look online for one to do your l top.
One thing i notice from your first post is no polarity change over switch in front of fuse box and between mains input plug, it has been known for some sites to have the pos and ground/neg wired wrong way round, very dangerous as all unit switches will be neg/ground and things like kettle bodies live, £40 odd bucks well spent.

 

[UsedtobeGinger]

A inverter to charge a laptop is over the top, many do this but as above a cigy charger which ups the voltage is cheap and simple, look online for one to do your l top.
One thing i notice from your first post is no polarity change over switch in front of fuse box and between mains input plug, it has been known for some sites to have the pos and ground/neg wired wrong way round, very dangerous as all unit switches will be neg/ground and things like kettle bodies live, £40 odd bucks well spent.View attachment 6558

I will look for the ciggy voltage raiser thing, thanks for responding.

But if I have understood your second point, if the polarity of the EHU input was reversed, wouldnt this throw the double pole breakers in the RCBO and the Consumer unit? I had thought the possibility of reverse polarity was why the advice is to use double pole breakers, rather than single pole. Though I can see why, if you already had a system with single pole breakers in place, it might be a good option to fit the item you show.

 

[UsedtobeGinger]

... sorry, more accurately, I should have said if reverse polarity (misnomer really) occurs then a double pole RCD will throw in the event of eg an earth problem.

And my understanding is that AC "reverse polarity" is only really a safety problem if there is a fault issue with your system - if there is no such fault, then everything will still work fine. But if your consumer unit is only single pole, reverse polarity means that if there is a fault, only the normal live side would be disconnected when an earth fault is detected - which would in fact leave the normally neutral (but in this situation live) side still connected + risk of shock. Double pole would disconnect both sides if there is an earth fault, so doesn't matter whether there is "reverse polarity" or not.