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Building a Home Workshop, Part 7

Getting power where it's needed

by Julian Edgar

Click on pics to view larger images

At a glance...

  • Positioning power points
  • Single high current power point for charging an electric car
  • Electrician quotes...
  • ...and final prices
  • Sourcing parts
  • Finished - power and lights working!
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Last week we looked at the lighting systems being used in the workshop. This week it’s time for power.

Power Points

It’s one of those things that sounds pretty simple – where in a workshop to put the power points. However, if you want the best outcome, it’s anything but simple.

For example, many people distribute the power points evenly around the periphery, eg in a shed putting one double power point in each bay. But that assumes that the requirement for power is also spread evenly throughout the workshop.

And that’s not normally the case.

In fact, before you can know where to position the power points, you need to have a good idea of how the workshop will be organised.

Click for larger image

We will cover the reasons for the internal organisation in next week’s article, but at this stage just take a look at where things will go. (Note: these diagrams are only roughly to scale!)

As can be seen, across the back wall of the shed (ie, the far wall as you enter through the roller doors on the right) there are: lathe, mill, bandsaw, and a bench housing a sander, grinder, drill press and hydraulic press. Furthermore (and not shown on the diagram), tucked below the bench is an air compressor.

Therefore, just across the shortest wall, there are seven machines requiring power. Clearly, lots of power outlets are needed here!

But you can go one step further. Both the mill and the lathe may well need a second power outlet for each machine. For example, each might need a suds pump to circulate coolant over the item being machined. Each might also need a dedicated work light. So it makes sense to provide both the lathe and the mill with double power outlets.

The bandsaw, grinder, sander, drill press and compressor are most likely to need one power outlet each – so that’s two-and-half doubles. So, leaving one spare outlet, that adds another three doubles.

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Put these power outlets on the diagram (each green dot a switched double power point) and the distribution looks like this.

But hell, go on at this rate and the workshop will have something like 25 power points! That’s far more than is needed, so let’s apply the same logic we did to the first section of the workshop – what power-using activities will be taking place?

Certainly, the island workbench will be a hive of power use. An angle grinder, jig-saw, portable electric drill and other electric hand tools will be often used. Rather interestingly, each of these tools can also easily cut or penetrate power cables, so here another aspect needs to be considered – safety. By far the safest way of getting power to a bench is by means of a hanging power socket. By plugging into a socket located above your head, cords no longer need to run across the floor and the workbench itself.

Click for larger image

So we can add a hanging power socket located above one end of the workbench. We can also put in another hanging power socket, along the same plane but located closer to the centre of the workshop. Remember, these are above head height so don’t intrude at all.

About this stage I physically stood in the near empty workshop, muttering to myself and pretending to do jobs.

“OK, I need to make a bracket. I’ll cut it out with the bandsaw, smooth the edges with the belt sander, drill some holes in it with the drill-press.

“OK, time to turn up the radio.”

Click for larger image

Er, but where’s the power outlet for the radio? There isn’t one! Something as simple as that – a radio needs its own power outlet within easy reach of the workbench. Ditto for a cooling fan. Here the extra power outlet has been added.

Time for more talking to myself.

“Ok, now I’ll install the bracket under the bonnet. Bring the car in and park it at a slight angle to enhance access.

“Now where’s that power point for the electric drill?”

Click for larger image

Here another three double power outlets have been added. The one nearest the roller doors will be mounted adjacent to the switchboard, near the light switches and another special power outlet I’ll come to in a minute. As can be seen, the north-east part of the shed is being designated as the ‘car working’ area.

(So what’s that darker blue car that never moves? It’s very likely to be an old car being restored, or a new unique car being built. I know from experience that will be something or other that just takes up space for years – and rather than pretend it won’t happen, I am organising the workshop around it!)

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So what about power outlets on the southern wall? I think only one double will be needed. The grey object, the pan brake metal folder, weighs a huge amount so once it’s in place, it’s very unlikely to be ever moved.

Totals

Let’s add them up. The wall-mounted power points comprise 10 doubles – a good number, as power points can be bought in bulk in packets of ten. In addition, there are two hanging single power outlets at the ‘working’ end of the workshop.

In case I need power outside the workshop, there’s a power outlet close to the doors, and there’s a ‘surplus’ power point near the workbench for a radio or fan. The permanently installed power tools each have power access, and power tools that will be rolled into position for relatively rare use (eg power hacksaw, friction cut-off saw, wood-cutting saw bench) can use the hanging power outlets or those on the north wall.

Handheld power tools being used on cars can also use the north wall power outlets (three doubles in this area), the single southern wall double or the single hanging nearest to the workshop centre.

The Special Power Point

Click for larger image

And there’s another, special, power outlet I want installed next to the switchboard. It’s a high current power outlet. Most power outlets in Australia are rated at 10 amps but you can also buy power outlets capable of much higher currents. How high then? Well, without going to a three-phase power system, you can have a 32 amp power outlet, a design that has a uniquely configured socket and plug.

And why have a 32 amp power point? It makes it so much easier to charge an electric car....

Electrician Quotes

I started buying the power outlets many months before the shed was built.

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Using eBay, a packet of ten double power outlets was bought for AUD$55 and ten deep mounting blocks for $19. These prices are way under half what my local hardware store charges - and the goods were brand new.

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To form the mounting plates for the power points, galvanised sheets were cut and folded so they would clip around the top-hat shape girts (longitudinal wall beams). These plates were then pop riveted into position.

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The hanging power outlets (three were bought although only two were used) cost about $30, complete with hanging chains. These were a second-hand eBay buy.

As covered last week in Part 6. I also bought on eBay the surface mount sockets for the metal halide lights.

But it wasn’t until I started to get quotes for the electrical work that I realised that I’d be buying nearly everything in the way of hardware!

In short, the quotes for the electrical work were amazingly high. This is what needed to be done:

  • Wire the 12 metal halide lights to two switches, in two banks of six

  • Wire the three compact fluorescent lights to one switch

  • Wire an outside light to one switch

  • Wire 12 power points, probably in two circuits

  • Install a switchboard containing two RCDs (safety switches), two 10-amp circuit breakers, two 20-amp circuit breakers, one 32-amp circuit breaker, one main switch

  • Install a 32 amp power outlet

  • Run a cable from the house

  • Install a 50 amp circuit breaker on the house board

Remember, all the power points and lights were already supplied and mounted, and the trench would be pre-dug.

The first quote was $2200, but that included the supply of the 32 amp power outlet ($300!) and a plug to suit it ($140!). The switchboard, cable, conduit, main switches and some of the circuit breakers were also to be supplied by this electrician.

After I lifted myself off the floor, I consulted eBay to find a 3-pin 32 amp power outlet (good brand, secondhand but in near new condition) for $58 including postage. I don’t have an immediate need for a plug to suit this socket, so that knocked $382 off the $2200 quote.

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I then went chasing circuit breakers, to find that they’re available brand new on eBay for $3 each – no mis-print! I didn’t have these individually priced from the electrician but I can’t imagine that they’d be anything like this price if supplied. Four-pole RCDs (safety switches) were only $25 each!

So when the next electrician came to quote, I said I’d be supplying everything but the switchboard, conduit and cable. His quote was $1650.

The next electrician, despite having nearly everything supplied, said that it would take two blokes two full days – and so the bill would be $2200. After I was resuscitated, I asked if I could run the wiring in the workshop and they could just do the connections. That was OK but the bill would still be $1500.

This didn’t make a lot of sense. One electrician had said it would take 12 hours using one bloke, another said it would take 16 hours with two blokes – WTF? One guy was quoting $2200 supplying nearly everything, and another was quoting $2200 but supplying only the cable, bare switchboard and conduit.

I am not begrudging someone earning a decent rate of pay for the job they do. So to get a feel for the job, I totted-up how long I thought it would take me to do it, if I knew my way around switchboards and – more importantly – if I was legally allowed to do it.

  • 12 power points at 15 minutes each – 3 hours (power points already mounted)

  • 12 lights at 15 minutes each – 3 hours (lights already mounted)

  • 3 lights at 15 minutes each - .75 hours (lights already mounted)

  • Running cable for above – 2 hours

  • Switchboards – 1.5 hours (switchboard already mounted) [Note: this was the only guesstimate I got quite wrong – in actuality, it took the electrician more like 3-4 hours to do the two switchboards]

  • Outside light - 0.5 hours (light already mounted)

  • Running cable to house switchboard – 1 hour (trench already dug)

Total: 11.75 person-hours

Clearly – clearly – the quote that said it would take two men two full days (ie 32 person-hours!) was just crazy, and the quote that budgeted 12 person-hours was about right.

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So I went back to the ‘12 hour’ man and asked for a revised quote if I supplied everything but the cable and the conduit. His quote dropped to $1100. (Later, when I added the installation of a [supplied] safety switch for the house switchboard and added-in the two hanging workshop power points I’d forgotten to initially mention, the price went up to $1300 – so, excluding the extra safety switch that’s not part of the workshop build, say $1200.)

As with the price of the shed itself (see Building a Home Workshop, Part 1), it sure pays to shop around and to do absolutely as much as possible yourself!

So what electrical parts did I need to buy and how much were they? After discussion with the electrician, here was my additional shopping list (remember, cable and conduit were being supplied by the electrician).

  • 2 x 20-amp circuit breakers (for two power point circuits)

  • 2 x 10-amp circuit breakers (for two lighting circuits)

  • 1 x 32 amp circuit breaker (for the 32 amp single power outlet)

  • 2 x 4-pole RCDs (protection for whole shed)

  • 2 x 100-amp main switches (one for house circuit board, one for shed)

  • 1 x 18-pole power board (to mount the above components on)

  • 1 x small junction box (to connect the hanging power points to the rest)

  • 1 x 50 amp circuit breaker (for the house switchboard, to cover the shed)

These components were all bought from the one eBay supplier – the same firm that had already supplied the power points, metal halide light surface mount sockets, and the power point mounting blocks. The bill for the above listed components was just $140, including postage.

Electrical Work

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I watched every step of the way Steve the electrician worked – not because I wanted to check up on him, but because I wanted to learn. And to be honest, nearly all the wiring was very simple - and that which wasn’t simple, could be understood after a few minutes of explanation.

I’d suggest that anyone who can find their way around the engine management wiring of a car could, after a day of instruction, safely wire a shed – and after a week of instruction, be able to do it just about with their eyes shut.

However, here in Australia – and especially in the state of Queensland – it’s illegal to do any mains power electrical work without the appropriate licenses.

So I got to sit around and watch Steve wield his screwdriver. That’s not quite true, because I had to dig the trench (probably the hardest work in building the whole workshop!) and run a cable.

Conclusion

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As you’d expect, having proper power points in the workshop, and being able to switch on the two lighting systems, made an immediate and radical difference to the ‘completeness’ of the space. It also meant that full-on attention could be given to organising storage – and getting the machinery into the workshop.

Next: organisation and storage

Go here for the next in this series.

Interested in home workshop projects and techniques? You’re sure then to be interested in the Home Workshop Sourcebook, available now.

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