110V

[Safety]

Hi all,

I am looking for guidance on why we should use 110v on a construction site, Is there any legislation that bans 240v?

[Whitehall]

It is not banned, but follows the very essential principles of reducing risk- good ol' ERIC PD

By reducing to 110v (which is not always possible) you certainly reduce the chances of a work place fatality should there be a problem.

You would have a tough time justifying why you chose 240v when a 110v was possible to the family of the loved one that was killed and the courts.

It is all about simple reduction of risks, limiting the potential of the hazard to cause harm.

No legislation that is so literal, but clearly reasonably foreseeable, reasonably practicable both apply.

[ddlh]

Agree with above - by using a 240- 110 transformer you will reduce the risk of fatality in case of electric shock. (Note not eliminate but reduce the risk!) Best practice in most industries Safety

Dave

[say-fish]

It's best practice to use 110v and most tools nowadays that aren't battery powered are 110v, you can however buy plug in RCDs which plug into 240 supply which you then plug your tool into, I would highly recommend this as any damage to the cable (which is the biggest concern on a harsh construction sites) will cause it to trip and cut the supply immediately, at least if something did happen and somebody got electrocuted you would have been seen to at least apply one principle of preventionl, somewhere between isolation and reduction

[kevlarion]

you'll find 110V more reliable than 240V with an RCD.
110V transformers don't have an RCD on them, so they don't trip if something goes wrong unless the circuit pulls too much current (like a short circuit) but it will continue to function if there is a bit of current leakage.
110V systems are actually 55V - 0V - 55V which is only a few volts higher than the voltage on a telephone line. While it doesn't eliminate the risk of electrocution, you would have to try quite hard to do permanent harm with 55V to earth. You can however do serious harm with 110V and no earth.
The downside of low voltage systems is that they pull a higher current than 240V systems. A 1000W tool will pull 4A on a 240V circuit, but will pull over 8A on a 110V circuit.
In order to accommodate this higher current without overheating the cable 110V circuits usually have thicker conductors than the equivalent 240V circuit.

It's important to match a 110V transformer with the amount of power required by the tools that will be used on the circuit, and their length of use.

Transformers are rated using KVA, since a VA is a Watt, KVA is the same as KWatts.
If you are using a 2000W angle grinder on the circuit, you will need at least a 2KVA transformer.

Transformers also have a duty cycle, and for the sealed IP65 type you use on building sites this is usually 25%, so you can run it at full power for 15 seconds out of every minute. If you go over the duty cycle a lot a thermal cutout switch will disconnect the transformer until it cools down a bit.