Off grid Consumer Unit to ring sockets

[satnas727]

Hi, I have 500W, 30A MPPT Charge Controller, 2 x 110ah Leisure Batteries & 1000W 24 V inverter. I want to run a ring circuit of 4 double sockets around my log cabin. Can anybody give me advice on the consumer unit from the inverter and what MCB do I need with instructions. Any photos or drawing wold be great

 

[Marvo]

Why do you specifically want a ring circuit, why not just a radial? I'm assuming the sockets are for 230v appliances so you're only going to have a 4Amp supply connected to 4 double sockets, you could just run a radial using 1mm flat twin (depending on length and installation method) and protect it with a 6A MCB.

 

[satnas727]

yes but I am told to use 2.5 cable and on a ring unit its loss is less. I am willing to look at radial but as its wooden log cabin is this a fire hazard.

 

[satnas727]

is it better to have 3 double sockets to raise the amperage.

 

[Marvo]

With a 1000watt inverter the maximum current you'll be able to draw will be 4.25 Amps and that's also probably peak load not constant load capabilities. Even a 1mm cable is already probably oversized for the current available, install a 2.5 ring final circuit if you wish but it's a waste of copper and money if the inverter is the only supply you're installing.

The number of sockets you install makes no difference to the amperage available, however many you install you'll have 4.25A total available between them.

What are you planning to plug into this circuit?

 

[satnas727]

Run a TV, xbox one and sound system also cctv dvr system. should I increase the inverter to 2000w and still run off 6 amp in the consumer unit.

 

[Marvo]

Entirely your call, the 1kw will probably cover what you've listed but the minute you plug in anything that heats like a kettle or fan heater etc it will trip. Even if you use a 2kw inverter to supply the sockets a 1mm flat twin radial circuit should be fine as long as you're not installing the cable in an insulated wall or something similar.

 

[satnas727]

Thanks the cable between the inverter to the consumer unit any ideas on what to get.

 

[Marvo]

Does the inverter have its own built-in over current protection and On/Off switch? What is the make and model number of the inverter?

 

[satnas727]

Sunshine Power Inverter 1500W 24V Pure Sine Wave Sunshine Pure Sine Wave 1500W 24V.

 

[Marvo]

That's a 1500 watt inverter, I thought you had a 1000w watt version.

It comes with its own built-in overload protection so why install a consumer unit?

This kinda inverter is better used with extension leads as it was intended by the manufacturers. One of the technical issues with this type of inverter in a permanent installation is that the neutral and live usually float with respect to earth, ie there's no internal N-E bond in the inverter so you really should use 2-pole switching if the sockets are switched. Also you have the earthing issues to deal with if you install a CU and hard-wired sockets, you'll need to install an earth rod and bonding if necessary and somehow create a N-E bond on the supply side external to the CU.

Just use extension leads, it's going to save you a lot of headaches.

You say in your profile you're a trainee, is this a job you're doing at someones property?

 

[satnas727]

The inverter is the only item I have not bought yet can you recommend one to me for wiring with a consumer unit if you can, Sorry for the confusion.

 

[solarfred]

I have considerable experience of generic Chinese inverters. I would seriously consider using eg. Durite or Victron. They cost more but there is a big reason for that. Your biggest fire risk is from a cheap inverter not the wiring.
If you are running CCTV then you may need a bigger battery bank. Check the amps of the recorder (which I guess is AC). If you leave the inverter on 24/7 it will kill your battery. Inverters need to be switched off when not required on small systems. If you know all the loads and have worked out the daily watt hours then you may be OK. However 500watts in winter is not a lot for constant loads after a few days of dull weather the alarm may go off. You have 50% of 110ah of storage for maybe a week of zero solar. Also these cheaper inverters are normally set to switch off the loads when the voltage is 10.5v (x2 for 24v)which is death for a battery. I would get a controller which monitors and controls the loads to cut off before damage is done. Decent MPPT controllers can be programmed to do this with their respective inverters.

 

[satnas727]

What is the best inverter to buy to wire to a consumer unit. Any links for the inverter and the cable to the consumer unit.

 

[Marvo]

I've used the Victron inverters and they're good units, not cheap but you get what you pay for. MultiPlus - Victron Energy As Solarfred says the Chinese inverters are something of a lottery, there's a few solid ones but plenty you want to avoid. I'm not sure about other makes and models available in the UK.

To measure the load you should use a test lead and a clamp meter with a 'max hold' facility. If you take the power requirement from the info sticker on the individual appliances it will be highly inaccurate. Make up a test lead like this and use it to actually supply the items.
(obviously use a UK 13A plug and trailing socket not the 16A version shown)