Electrical install for my shed

[techguy]

First of all, am I allowed to do work myself? I would say I am fairly competent and I absolutely respect the dangers of electricity.

I have a small shed, which I want to put two 10W LED flood lights and a 13A socket on the side of.

There is no mains supply to the shed and I was thinking of putting a leisure battery in the shed, which will be charged by a small solar panel on the south facing side of the roof.

A 1000W inverter connected to the battery will supply a CU.

CU will contain two MCB's (one for the lights, one for the socket). Both will be fed from a 30mA RCD (it's no worry if one circuit trips the other).

As I am using a 1000W inverter, the outdoor socket will be fused at 3A. It will only be use to power a fridge or other low power devices such as other LED lights.

LED flood lights on the shed will be individually switched by a double switch. All outdoor equipment will be IP67 obviously!

For safety I intend to have isolation switches between:

solar panel and battery
battery and inverter
inverter and CU (outside shed)

I don't believe the AC supply from the inverter will be earthed (I can't see how it would be as there is no provision for an earthing rod or anything). Is this acceptable considering the circuits will be RCD protected?

Also, which size wiring should I use for everything? Is 1.5mm fine or should I go smaller? Can I just use twin and earth for everything? For the connection between the inverter and CU (through isolator switch) I was going to use a lawnmower power cable with the end cut off and a 3A fuse in the plug too.

Everything will be sufficiently labelled and there will be warning stickers everywhere! Note that the entire install aside from the actual LED lights, socket, and isolator switch will be inside the shed which is locked and only I have access to.

Thank for all your help, tips etc.

 

[Midwest]

OP if you respect the dangers of electricity, I would engage the services of an competent electrician and one that has a good working knowledge of PV as well.

 

[HappyHippyDad]

As above Tech guy, I would definitely contact an electrician (one that understands solar) or else spend alot more time reading and understanding about 12V supplies. What you have suggested above would be dangerous and that is not just some forum person being over cautious it really would be dangerous.

1. You have no device to stop the battery from over charging, you need a charge controller, this charge controller should be of the correct current rating.

2. A 1000W inverter means that the current going through the cable from the battery to inverter could reach 83A (1000/12) so needs to be 16mm or 25mm, not 1.5mm which would melt in no time.

3. The RCD won't work as there is no earth and no supply earth (this is something I have only just learnt http://www.electriciansforums.co.uk...ctrical-forum/110106-does-system-look-ok.html)

4. Unless the isolation switches have fuses in them you will have absolutely no protection of any kind in your entire system.

5. IP 67 is overkill IP44 is adequate.

6. Have you done any of the maths to determine panel size, battery size, inverter size required etc

If you really don't want to get an electrician and plan to do this yourself then please spend a few weeks/months reading through the internet (there are many websites explaining solar panels) and getting more of an understanding and then also perhaps pop back here with your new system and then the members can offer some advice, but at present I would not go ahead with what you have suggested.

 

[DPG]

I was waiting for your comment hhd! Daz

 

[HappyHippyDad]

Am I that predictable Daz!

I got mine up and running today and it works just as it should, even the 2000w inverter! Very happy!

Obviously didn't put an RCD in as it wouldn't have worked, everyone knows that! (That was a dig at myself OP not you)


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[HandySparks]

HHD,
You've covered most of the issues I thought of but couldn't be bothered to write out.

I'll just add that, if the output of the inverter is connected by a plug containing a 3A fuse, there isn't much point having the circuit breakers.

Also, a fridge might just pop the 3A fuse or hit the limit of the inverter on start-up.