Generator connection

**IanF** · 23-Jan-15, 11:46 AM

Originally Posted by Houses4Rent

I am thinking of a far simpler set up. I really only need power during load shedding and other outages for my PC, printer, router, screen etc. so I can continue working. Is it feasible if I buy a small genny (what size would I need?) and when the power went I just start up the genny and use an extension to plug my PC gear straight into the genny.

What are the pros and cons/risks?

That's what I do. Then when the power comes back the lights come on.

**KCS** · 23-Jan-15, 12:59 PM

We have kept it simple, as we don't need to power the whole house during the outages. My big concern was charging my laptop, phones, security and the fridge. The rest we can do without, and we use battery LED lights. Also have gas for cooking (braai!)

In view of this I bought a 3,5 kva generator which I installed with a nice thick lead to a multiplug, located near the fridge. During outages I just plug in the fridge, and switch off the fridge when we need to boil the kettle or charge any of the devices. The generator has a decent earth into the ground, as well as AVR (I assume this means Automatic Voltage Regulator?) as well as an overload cut-off.

This kept it really simple and the cost very low. Also, I never plug the computer straight into the generator power supply, only use it to charge, so I assume that the charger will take the brunt should there be a spike in current?

The question marks above are assumptions, I am not an electrician. Would welcome comments.

Cheers

KC

**ians** · 23-Jan-15, 01:14 PM

Originally Posted by AndyD

The problem with a lot of the small generators is the the neutral is at an equal voltage as the live with respect to earth so they're configured 115(L)-0(Earth)-115(Neutral) L-N is 230v. You cannot connect this type of genny to a DB, it's designed for use with trailing leads only. Also genny's are notoriously poor at producing sufficient current in the case of a fault and don't achieve required disconnection times of circuit breakers or other OCPD's.

Andy why did you have to go spoil it and bring that up. That is why you have to plug it in so that it doesnt become part of the electrical installation. We discussed this issue during the last load shedding episode. Just imagine trying to stop all these generators being connected, there are thousands of them connected to DB's. The worst i have seen to date are the suicide cords, with the plug on both ends of the cable.

**AndyD** · 23-Jan-15, 05:35 PM

Eek, 'plugging it in' would not be a wise move.

Originally Posted by Dave A

Is the earth tapped in the middle like that, or is it just that without an anchor the live and neutral float off the "ambient" earth voltage in equal measure?

My experience so far is if you bridge the earth and neutral at the generator, the neutral stays at 0V and live goes to 220V relative to earth, which solves the problem. Of course, make sure your earthing system is appropriate (have an earth spike).

In some smaller site type generators the centre of the windings is actually tapped and bonded to the chassis as an earth which ties both L and N at 110v wrt earth, they're not floating. The problem is when the centre tapped earth is bonded internally to the generator chassis. If you bridge a centre tapped earth and neutral you're effectively shorting out half of the winding which would cause a fault condition and probably damage to the windings. This is what would happen with a cowboy connection into a DB.

These generators are designed to be used with extension leads only.

**Houses4Rent** · 24-Jan-15, 10:00 AM

Hm, can you sparky's please tell me and KCS how to set up a very simple thing like a generator powering a few things of choice via an extension lead?

I won't need a fridge/freezer as it can survive 2.5h load shedding. I really only need to power my PC (desktop), router, printer and scanner without risking frying any of them due to problems induced by the generator (Voltage & Amp variations). I can charge my cell via USB from the PC

**AndyD** · 25-Jan-15, 12:14 AM

Originally Posted by Houses4Rent

Hm, can you sparky's please tell me and KCS how to set up a very simple thing like a generator powering a few things of choice via an extension lead?

I won't need a fridge/freezer as it can survive 2.5h load shedding. I really only need to power my PC (desktop), router, printer and scanner without risking frying any of them due to problems induced by the generator (Voltage & Amp variations). I can charge my cell via USB from the PC

Just use extension leads to your PC'sand laptops etc. The stability of the voltage and frequency of the generator power is down to how good the built-in AVR is so for electronics it's always worth spending a bit extra and getting a decent genny.

**Houses4Rent** · 25-Jan-15, 10:56 AM

Thanks Andy, but how does one establish what is a decent genny and AVR? Any trusted brands/sources which can be named (Cape Town).

**AndyD** · 26-Jan-15, 12:30 PM

I've got limited generator experience but I've always paid the extra and purchased Honda. So far I've not regretted it, some of my gennys have not had an easy life and are over 10 years old.

As with anything I'm sure there's some Chinese brands that are very respectable but the problem is there's a lot that aren't and most of the time you're relying on info from the salesman who's going to tell you anything. The number of times I've heard 'they're made in the same factory as **insert well known brand name**' is laughable and not just for generators.

**ians** · 27-Jan-15, 04:54 PM

Something to note, not all small generators cannot be connected to a house. I indicated to a customer today that it was not wise to connect a small generator to a house. He set the record straight with documentation and a diagram showing how to do it.