So, my MIL recently had a small backup system installed so that she could have lights and watch DSTV if needed during load shedding. Requirement was for plugs in the TV room, and all lights in her small retirement unit to be operational when required. Thus only lights on in TV room when watching TV or one or two others when going to the toilet or bed etc. Loads at any one time would be small LCD TV, DSTV decoder, couple of lamps, and occasional lights. Very basic, as cheap as possible.
Got a few electricians to quote but settled on a local electrician, who had done work for her before, to come and install a solution. My wife was visiting whilst this was installed and took a couple of pics. Now I’m no expert but I have a basic understanding of how electrics work and I reckon this install is a bit dodgy.
El-cheapo inverter/charger installed in garage with 2 x LA batteries. Incoming power via wall socket in garage. Outgoing power going from 3-pin socket at back of inverter into conduit into roof, down into DB to 3 x circuit breakers, 2 x lights and 1 x plugs. No other circuit breakers or earth leakage, no fuses/disconnect to batteries, etc. The sparky has committed to providing a CoC but he keeps avoiding her and making excuses for not getting back to her.
Is this safe? Is this legal? Comments/ from the experts please.
The one thing that I would have a look at, is the batts being open, specifically the poles.
Regarding the rest, some others may have a thought or two. But one would think that the inverter-fed circuits, would be clearly marked, and I supposed there is a changeover, to switch those circuits back if the inverter/batts are worked on?
Those are some of my concerns, nothings labelled, there is no changeovers, you unplug the 3-pin from the back and it disconnects the lights and plugs so no backup if the inverter or battery fails.
Also, what happens with earth leakage on the plug circuit when Eskom power is off and the inverter is feeding the plug circuit?
We see the same thing.
Some clever people are here … they will be around.
EDIT: I refrain from saying too much on this matter, as I have a very bad track record.
It seems the backup system doesn’t have any E/L protection. Big no no. Also no clear marking of different supplies feeding into 1 DB. No Change over. Open terminals on batteries. To name n few.
OK let me list 'em.
- You may not connect a generator or inverter to a fixed installation unless it is TN-bonded (neutral is tied to earth). Your el-cheapos generally don’t do that. Without going into details, the regulations are such that the only way to legally do this in SA is with a “bonding relay”. Victron inverters have that built in. Newer Voltronics (since around 2017-ish) too. Sunsynk has an external boxy thing for that. The al-cheapo will not have it.
- No double-pole issolator on output of inverter. There must be a way to issolate the inverter completely.
- The RCD, as noted. It must have an RCD on the output. If you have space-in-the-DB issues, a combined RCD/overload breaker is expensive, but less than a new DB. You can also put a small DB in the garage with a main (inverter) double-pole breaker, and an RCD, before it enters the conduit going over to the other DB. That would be my preference.
- It’s not completely clear if there is a separate neutral bar. It looks like there might be. Backup loads must have their own neutral bar for the circuits that are backed up.
- There should by physical separation in the DB between your backup circuits and the rest. I don’t like it that those three breakers sit in the middle of the rest. Move them to the right end, and label it properly.
- Running inverter from a plug point in garage. No man… you have a conduit going there already, pull in a line and drive it from a breaker in the DB. You could have done that at the same time you pulled in the other wires…
- Changeover switch… again, could go in a small DB in the garage.
- Inverter spec sheet says it does reverse polarity protection by short-circuit and expecting a fuse to blow, but there is no indication of a fuse installed in the inverter. Therefore that DC line MUST have a DC-rated fuse! This is probably by far the most dangerous part of this install.
- DC cabling looks thick enough for the 35A-ish it has to carry.
- Take out the terrible double-adapter on the output
That’s it from me…
Edit: Oh, and I’d over-current protect the entire thing with a 15A breaker. Why? Because I don’t trust that three-point plug on the output to do more than 16A for long periods.
Awesome, thanks Plonkster.
Im very much on the same page that teh install is “dodgy” from what I have seen recently from similar installations at a number of friends places, these units are labeled as “UPS” and the sparky’s that install them take that term with a bit more than a pinch of salt. As you dont have an RCD connected to the UPS that runs your computer, so why connect one tot this unit?
This does spark a question in my mind, Do the mecer trolley inverters have a RCD on its output?
Same principle applies. Sparkies are just pretending that the circuits you are running are “extension cords” to appliances.
Happens way too often at the moment,
They don’t, but they are also not meant to be tied into a fixed installation.
That’s the issue here. The moment you tie it into a fixed installation (in other words, into the DB), then you need to tick these boxes:
- Must be TN bonded
- Must have RCD protection
For things that are not fixed… the regulations don’t care. Once the energy leaves the wall socket… it’s no longer their problem
It’s more of an issue than people think. How many bed lamps have cabling good for maybe 5A or 10A, with a cheap switch… and the only thing protecting that from bursting into flames is a 20A breaker in the DB… and we’re kinda FINE with that…
Edit: That is one place where the British system, that holds a fuse in the plug, is technically superior to ours.
I would rather just pull power from the main db along with the 3 circuits into the garage and add a new db with changeover, protection, etc in the garage.
I guess if this inverter fails, then you can just unplug the the output of the inverter and plug it into the wall again.