Electrics

3 Phase weirdness

So on Friday the 13th we get home to some strange effects. Turning just about anything on makes some of the lights go brighter. The fridge affects the garage lights. The geyser affects the kitchen lights…

Having a working knowledge of 3 phase power, I realise that the neutral wire has come adrift*. Check the box, all looks good. Check the outside box, nope, neutral is floating out there too.

So I unplug everything I can, phone City of Capetown, they’ll send a team. All good. We go out Friday night. We go out Saturday morning. Get back, no change.

I get on the roof, check the wire where it comes into the house. No, problem is definitely on the pole. Phone council again.

Well, they eventually pitched at around 1900 Saturday. And after some stuffing around, found the problem (where, according to them, a previous team had taped over a potential problem which then a few years later hecause a real problem).

These teams are amazing. They still had four jobs lined up tonight, fellow says they get to the depot at 2200 and home at 2300, then are back on the job at 0600. But I’m glad to say he says the pay is good.

Casualties: pretty much the little things that are permanently connected but draws little power — the microwave, two clock radios, computer speakers, the wall wart for the telephone…

* When neutral is not connected to the transformer, a load on one phase pulls neutral towards the line voltage, and in doing so pulls neutral away from the other two phases. The loaded phase falls to say 120V while the other phases go up to 300V or so (relative to neutral).

2012-04-14 by wrm House 1

3-phase redundancy

So there I was, pottering around home yesterday morning, and suddenly the lights go out. And the bleating of the UPS reaches my ear. Some inspection shows that the fridge is still working, Tamsyn is still happily playing on her computer, and all the trip switches including the big ones in the box outside are happy.

Further inspection shows that we have one phase of the three phase circuit, and even further inspection shows some very dodgy looking wiring on the pole side of the feed.

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So Tanya gets instructions to phone council and I bugger off to work.

Long story short, at 1800 it was starting to get dark inside the house, and we still had only the one phase.

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Battleshort!Â I disconnected the two dead phases, and shorted all three phases together on “my” side of the mains breaker (which is the bottom of the bottom left switch in the first picture, but I did it at the input side of the breaker that feeds the garage, just because it was more convenient.

So around quarter past eight, just as I’ve put the bread in the oven [1], the crew pitches.

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Of course, they had to cut all power to fix the feed, and when they reconnected the power everything now hanging off the one phase was cold, so that tripped the outside breaker, which lead to the quickest removal of a kludge you can think of (figured I had to remove all evidence of my meddling before they came inside to look why the lights were not burning…)

[1] We had friends over, and I make Pioneer Woman‘s Marlboro Man’s Birthday Dinner (well, the pan fried steak with blue cheese sauce, crash hot potatoes, and buttered rosemary rolls part of it). With store-bought dough in my black pot, Porterhouse steaks from Constantia Pick & Pay, and lemme tellya, that blue cheese sauce is something else.

2010-01-27 by wrm Foooooood Geek House 0

Undercounter lighting

I wanted to use low-voltage LED undercounter lights in the kitchen. I liked the strip lights from LED z Shine, so I phoned a rep, who promised to get back to me and then… things went quiet. Contacted them recently, but they don’t deal direct and suggested I go to Eagle. The guy at Eagle was particularly non-helpful, said he’d have to order the stuff in and made it clear that he didn’t really want to do that.

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So the other day in Cape Town I walked past an electrical store (RG Jack in Bree Street) on my way from the toy store. Popped in, found this 220V fluorescent strip light. It’s rather expensive, almost R600, except they then give 55% discount so it’s R255 out the door.

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It’s also rather bright :-)

Now I still need to add two switches, one for the undercounter light and one for the downlighters that still need to go into the glass cupboard.

2009-12-03 by wrm House 1

Sunday at home

Last Sunday I decided that I had to get my lazy bum in gear and finish the kitchen wiring.

Before and after. I built a 3 way multiplug into the appliance garage so we can leave the stuff plugged in, just pull it out to use it.

The plugpoint on the left is special. I originally bought it to use it in the bathroom, because hair dryers etc often have two pin plugs. But Tanya’s hair dryer has the “euro” connector that doesn’t fit into that socket. So I swapped a single socket into the bathroom and put this one here so that I can plug the wall-wart to charge the bamix.

All of this took longer than expected, and since I had been monopolising the kitchen the munchkins were hungry.

So Tamsyn made french toast. Using three eggs per person, so we had scrambled egg afterwards :-)

And we started a batch of ice cream but that will be the subject of another post.

Supper was my stoo on the left and vegetarian parsnip stew on the right. Both were great.

2009-05-19 by wrm Foooooood House 1

It doesn’t look like much…

…but it means one less extension cord to trip over.

The wire runs down through the ceiling behind the Colossal Cupboard, under the Hidden Door, and up along the door frame to the plugpoint.

With hindsight it would have been easier to fit the plugpoint before mounting the bookcase on the other side of the wall.

This is the second-last electrical run required. I still need to extend it to Jessica’s room and to the outside plug point for the washer, dryer and chest freezer. (The last electrical run will be for a plug point for Tamsyn’s computer). Edit : of course I’m lying, we still need plug points in the master bedroom, but for some reason that doesn’t come up on my radar…

The master bathroom’s looking good.

2008-11-26 by wrm House 2

What I did yesterday afternoon

I always get my best ideas in the shower. In this case, the best way to get power to the gate motor.

There’s a plug point in the living room, I drilled a hole through the wall, fitted this box on the outside, and ran a pipe …

… through this Malawian-dug trenchette …

… to this weatherproof box, where I will eventually fit a plugpoint for vacuuming the car …

… and via a flexible conduit you almost can’t see in the above pic, to the gate motor.

A dip in the jacuzzi with a good looking girl and a glass of red wine rounded off the day.

2008-08-27 by wrm House 1

Ouch eina moer

About four or five years ago I rewired the DB at Amperbo. It’s a 3 phase ‘box, and dated back to shortly after the second world war when my grandfather built the place — think ceramic holders for fuse wire, big switch boxes looking like something from Dr Frankenstein’s lab, and the like.

I replaced all most of this with modern trip switches, an earth leak unit, two geyser circuits, etc. We also ran new wires up to the loft for the geyser and lights, replaced some of the wiring to the plugs (especially the rusted pipe under the kitchen floor which shocked Pieter every time he cooked in bare feet), and so on.

Anywayz, at the time, we bought a 3 phase earth leak unit, cost a bit over R800, and we thought it was rather steep.

So I went to buy a 3 phase earth leak yesterday. R1715.

And thence the title of this post.

2008-08-14 by wrm House 0

Geek Alert : Electrickery

This is the distribution board (DB). The pre-payment meter (bottom left, outside the picture) was wired in later, see the taped wires on the left hand side? The extended wires go down to the meter and then back up to the mains switch at the bottom left.

The red/blue/yellow wires go to the switch at the upper right hand side, and from there to the cable that feeds the garage. That’s the whole point of 3 phase — power to the workshop!

Nicely balanced phases, one phase feeding plugs, one phase feeding lights, and the third phase feeding the geyser.

Only one problem — I much prefer my lights and stove to also be on the earth leak circuit (I got the worst shock of my life unscrewing an Edison screw lightbulb from a metal mounting. The socket was fed via ripcord / flex and obviously the outside of the screw was live. That house still doesn’t have earth leak, but then, I don’t live there any more).

Oh yes, the reason I’m tracing all of this is that I need a circuit for the oven, and two circuits for the jacuzzi (the jacuzzi is wired for a single 40A feed, but I have three 30A circuits only). I have the old stove (3 phase) feed, as well as two plug circuits, the one that used to feed the kitchen, and the one that used to feed the lounge. I’m planning to use the old lounge circuit for the kitchen, and the old kitchen circuit for the fridge and the washing machine / tumble dryer (which will have to live out on the back stoep).

Circuit	Current
Oven	14.5A
Dishwasher	~5.5A
Stove (Electric domino)	13A
Geyser	18A
Lights (estimate)	5A
Washing Machine	7A
Tumble Dryer	11A
Jacuzzi Heater	18A
Jacuzzi Pump	6.6A

I played with these values a bit and realised that I’d have to change things around quite a bit to balance the load on the different phases. I also grouped things together logically — we’re unlikely to use the oven and dishwasher at the same time, and even less likely to be in the jacuzzi with the pump on at the same time. So also, the jacuzzi heater can be on the same circuit as the washing machine and tumble dryer, those things are not likely to be used all at the same time… I hope. Comments are of course welcome.

Circuit	Red	Blue	Yellow
Plugs 1 (Bedrooms)		5A
Plugs 2 (Kitchen)			5A
Oven		14.5A
Living Room		5A
Dishwasher	~5.5A
Stove (Electric domino)	13A
Geyser	(18A)
Lights 1 (estimate)			2.5A
Lights 2 (estimate)		2.5A
Fridge			5A
Washing Machine			7A
Tumble Dryer			11A
Jacuzzi Heater			(18A)
Jacuzzi Pump	6,6A
Total	38A (20A)	27A	45.5A (27.5A)

(You’ll notice that the total is not the sum of the column — this is because, for example, the fridge, washing machine and tumble dryer is on one 20A circuit, if it draws more than that the subcircuit will trip).

A total over 30A total is obviously bad, since that would trip the mains. On the other hand, we can learn to not run the jacuzzi heater, the washing machine and the tumble dryer at the same time. The geyser can of course come on at any time, which is why they invented a little black box called a load control relay. I bought a 10A unit — if the stove circuit (stove, jacuzzi pump and dishwasher) draws more than 10A, the relay will make sure the geyser doesn’t come on. If I’m only using one of the stove plates, the stove will draw less than 10A and the geyser will have power.

I might end up fitting a load control relay to the jacuzzi heater circuit as well if things turn out to be a problem.

2008-08-13 by wrm Geek House 0