Which is best, single phase or three phase power on site?

Which is best, single phase or three phase power on site?

Site power can be the bane of the flooring contractor’s life. 110 volts (or 240 volts dropped down to 110) has its limitations. For the really heavy duty jobs 110 volt machines lack the guts or the power to do the job, and even where they can just about get by, they can add many expensive man hours to the cost of the quote.

For this reason, right at the beginning of the process, when assessing and compiling your quote make sure that the site has a power supply suitable for the machines needed to do the job.

If three phase or 415 volt power is already installed it increases substantially the options available. Most of the larger floor grinders and planers, shot blasters and larger dust control units require three phase power. The majority of commercial premises, blocks of flats and garages will have three phase. Small independent retailers and domestic houses are less likely to have it though a number will, for example food outlets with commercial ovens and tanning salons; so don’t assume power is not available.

If there is three phase power on site, it may not necessarily have the tell-tale red 415 sockets on the wall. Machines or equipment needing 3 phase may well be hard-wired into the building’s supply. In which case take a look at the distribution board and see if the circuit breaker has a single or a triple lever switch. The former is single phase, the latter is three phase. If three phase is available it is usually quite a straight forward and inexpensive job for an electrician to wire in a suitable socket. Most flooring machines use either a 32 amp or 63 amp, five pin 415v socket. If there is no three phase power in the building, having it installed is not usually feasible, taking several weeks lead time and a four or five figure installation cost. In which case maybe a generator is an option.

Yes, there are 110v equivalents but for medium to large jobs they work somewhere between eventual and unfeasible, and often with compromised quality. So be sure to stipulate that adequate three phase power must be installed before work commences. Alternatively, build into your quote the cost of hiring a large 3 phase generator. Be aware though that generators are not 100% reliable and have been known to break down, and also build into your quote likely diesel usage. The questions of transportation of the generator, security and insurance cover also need addressing.

Is three phase 415 volts safe to work with? Thankfully electrocution events are rare because plugs, cables and machines have adequate protection from the increased current. The rare events usually arise by not following common sense precautions -

Before starting work, undertake a risk assessment, identifying risks as follows :

  • Only ever operate machines for which you are competent and have had adequate training for.
  • Only ever use cables and equipment that have recently been electrically tested.
  • Never allow plugs to drag along the floor.
  • To unhook a plug from a machine or a power supply, always grasp and yank the plug rather than the cable.
  • Do not overload the supply; check the machine’s ratings as compared to the power supply’s amps. Under-powering a machine will cause the motor to burn out or set on fire.
  • Do not use too many cables. Multi-Hire restricts customers to hiring no more than three cables or leads per machine without good reason. This causes a voltage drop, machine under-power and a fire hazard.
  • Do not use electrical flooring machines in the rain, unless the manufacturer’s instructions specifically allow you to.
  • Switch off and disengage from the power source a machine before adjusting or repairing it. Do not attempt any repairs unless you have had adequate training.
  • Stop using immediately any machine that appears to be faulty.

Of course all the above do’s and don’ts apply equally to single phase 110 volts.

There is no good reason to avoid using three phase power and indeed by doing so you may well be putting yourself at a competitive cost and time disadvantage, as compared to a company comfortable using 415 volts, there’s no good purpose in using the wrong machine for the job.