Inline rcd no earth

[rasklit]

Id like to run one of my domestic lighting circuits from batteries (charged via solar panel during the day.)

Id like to "rcd/fused spur", protect the circuit after the invertor, before it goes into the changeover relay, but am struggling with the earthing aspect of RCDs.
Has anyone done this that they have a quick simple diagram. ? Thanks

 

[securespark]

You wanna do what??

Can you provide a diagram?

 

[mikeyd]

but am struggling with the earthing aspect of RCDs.

With all due respect: DON'T DO IT YOURSELF.

 

[rasklit]

You wanna do what??

battery - floating inverter - inline rcd/fused spur with 2a fast blow fuse - changeover relay - lighting circuit.
When the batteries discharge the inverter cuts out, cutting power to the changeover relay, which reverts the circuit back to the existing layout via the CU.

Its options for connecting earth and neutral on the output of the inverter, i think it depends on the output of the inverter eg 230 0 0 or 115 115 0 (which i dont have yet - its all still a thinking project)

Latest osg arrives today, im hoping it will shed a bit more light.

 

[rasklit]

but am struggling with the earthing aspect of RCDs.

With all due respect: DON'T DO IT YOURSELF.

If you were the electrician coming to install this system for me, would you prefer to be given a load of the wrong bought parts thats made it hard for you to do, or a load of parts that had been thought out a bit and made it easier for you to do.


Maybe it doesnt matter but im just trying to predict problems

 

[Aragorn84]

Surely the proper solution would be to ditch the battery and use a grid tie inverter?

 

[rasklit]

Surely the proper solution would be to ditch the battery and use a grid tie inverter?

This is about storing surplus during the day and releasing it at night...

 

[Aragorn84]

And a grid tie inverter does more or less exactly that by feeding the excess into the grid (which you get paid for)

 

[rasklit]

Doesnt work when there is a power cut though.
I have a 2kw generator to run large items when there is a power cut.
This about keeping the lights switched on as well, and the cheapest solution i can think off.

 

[Aragorn84]

Large batteries arent cheap though, and unless you go buy proper traction batteries, they certainly wont last long constantly being charged and discharged every day.

If your going to have a power cut, you'll be firing up the generator anyway, i just dont see the point in what you propose...

 

[rasklit]

, i just dont see the point in what you propose...

Do you not see the point in my wanting to RCD protect a dc powered circuit? - which is what I asked about in the initial heading,
or
do you not see the point in the whole idea? which is NOT what i asked in the original topic.

 

[Aragorn84]

The requirement for an RCD surely depends on what (and where) the circuit supplies, information which you have not provided.

The whole idea is barking mad. If you have mains power, continually charging and discharging a big lead acid battery is an extremely inefficient way to use the electricity produced by the sun. If you have a power cut, and happen to have a generator, then surely your just going to spark that up and power the lights from there.

Not to mention that if as you propose, EVERY night its going to then discharge and switch back to mains after the battery runs out, dont expect your battery to last much more than a couple of months, unless you spend a LOT of cash on traction batteries.

 

[rasklit]

Aragorn123 please stop banging on. All the rest has been worked out. I have an endless supply of batteries at vertially no cost.
Everything auto cuts out, when voltage drops, to protect the 120 ah deep cycle battery, the amps that would be drawn from the battery are about 10ah max, that includes inefficiencies from the inverters, and loss through the cables and diodes.

I know I do need to RCD protect the circuit as its the standard lighting circuit in the house already. Its already RCD protected through the CU, but when it is to be run from dc batteries, it doesnt run through the cu.

Please stick to the initial topic or shut up.
Im honestly wishing id never asked.

Would you believe that my local council building control guy has been far more helpful about this project than you.

Now youve made your point, you think its a crap idea, good for you.

Can a mod now please lock this topic, ive found the answer on a website for other idiots with the same idea as me.