Setting up for high power 230v machines, 20amp

[Doug B]

Make sure the rating for cable, flex, plug and socket is above that of the MCB.

I seem to remember that’s pretty much what my electrician mate said at the time though looking at that plate I can’t believe it’s 7 yeas ago He definitely said 2.5mm could take just over 20amps as he gave me the artic cable I used for the flying leads.

 

[Prizen]

1. How far from fuseboard to socket (cable length)?
2. How will the cable be installed (eg clipped onto wall, buried behind insulation,...)?

1. Shed is quite small. Cable run from shed fuseboard to each machine socket would be no more than 10m
2. Cable will be clipped onto a block wall.

 

[mindthatwhatouch]

I seem to remember that’s pretty much what my electrician mate said at the time though looking at that plate I can’t believe it’s 7 yeas ago He definitely said 2.5mm could take just over 20amps as he gave me the artic cable I used for the flying leads.

Sounds good, luckily I don't do much sparky work anymore.. lost count of the number of times Ive seen too small flex, connectors or components on something because its only rated at say 10 amps and the MCB or fuse is substantially larger. Sometimes installed by so called electricians.
The protection is there to protect the cable, not the equipment.

 

[mindthatwhatouch]

Sorry to clarify, I wasn't saying use SY for the fixed just for the flex.

10 metres is not a small shed!!!!

Personally I'd not use exposed T&E (though I don't know if that applies in this case)

Definitely type C breakers. (and what Guineafowl stated above )

 

[Prizen]

Sorry to clarify, I wasn't saying use SY for the fixed just for the flex.

10 metres is not a small shed!!!!

Personally I'd not use exposed T&E (though I don't know if that applies in this case)

Definitely type C breakers. (and what Guineafowl stated above )

The run might be up to 10m but my shed is only 8m long x 4m wide

 

[guineafowl21]

1. Shed is quite small. Cable run from shed fuseboard to each machine socket would be no more than 10m
2. Cable will be clipped onto a block wall.

2.5mm2 T&E will be more than adequate, in that case.

You might want to consider some cable protection, like trunking.

For the socket end, I assume the machines have a round, blue 16A type. You can get nice boxes with a blue socket and isolation switch built in.

 

[Doug B]

For the socket end, I assume the machines have a round, blue 16A type.

They arrive with just a short piece of flex,no plug

 

[Sideways]

Proforma comment in case anyone cares and for future readers of the thread.....
Installing a new circuit, breaker, etc is work covered by the BS7671 Wiring Regulations and Building Control in the UK. It's not considered DIY and is notifiable. That means designed and installed to standard, tested on calibrated equipment and results submitted. Any problems arising from DIY - including consequential damage to the equipment and property would be at your own risk.
I personally have no problem with folk making their own choices and taking responsibility for them, but if you haven't read the 450+ pages of the regs (and very few would do it for fun) you don't know what and how much you're unaware of. Just be aware that if you DIY, in the worse case you may find yourself uninsured or warranty voided.

 

[spb]

Proforma comment in case anyone cares and for future readers of the thread.....
Installing a new circuit, breaker, etc is work covered by the BS7671 Wiring Regulations and Building Control in the UK. It's not considered DIY and is notifiable. That means designed and installed to standard, tested on calibrated equipment and results submitted.

More than that - being notifiable means either a qualified third-party certifier is appointed (which will probably cost just as much as getting an electrician to do it for you), or building control notified of your plans, before any work begins. Building control will take note of the qualifications and experience of the person doing the work when deciding how much inspection they need to do, and they'll charge you accordingly.

BS7671 applies to any work done on a fixed electrical installation, notifiable or otherwise, and needs to be tested and certified. The difference is that testing and certification under BS7671 can be done by a competent person, not just a registered competent person, so it is feasible to do yourself provided you've got the right knowledge and equipment to fill in the forms accurately. For notifiable work (changing a consumer unit, installing a new circuit, or anything in the vicinity of a bath or shower), if you want to stay within the law, you're not likely to save much money, if any, over getting an electrician to do it.

 

[Prizen]

You guys in the trade?

 

[Sideways]

No But I have investigated DIYing notifiable work and decided it just wasn't worth the cost and hassle.

 

[guineafowl21]

No But I have investigated DIYing notifiable work and decided it just wasn't worth the cost and hassle.

You were absolutely right to post the above.

The reason I’m happy to give advice is that this forum is the right place for such advice. It’s not Facebook or some other social media guff. In an ideal world we should all get all electrical work done and certified by a competent professional.

I’ve looked into the legality of such things, asking a qualified electrician whose specialty is legislation. He posts regular videos examining the regs in detail. Here is a quote:

“For homeowners working in their own property, there is nothing preventing them from doing electrical work of any kind. The only applicable legislation is the Building Regulations, and that just requires that 'Reasonable provision shall be made in the design, installation, inspection and testing of electrical installations in order to protect persons from fire or injury.'
nothing more. Generally that's achieved by complying with BS7671 wiring regulations, but DIY work is rarely checked or tested by anyone, so plenty of non-compliant DIY work goes unnoticed and when it's eventually found, it's usually years or decades later and there are no records of who did it or when either.”

He goes on to cover notifiable work, such as adding a new circuit. This is almost never prosecuted, and if it is, it’s as a result of an accident and is lumped in with the other charges. In a nutshell, there is a big difference between filling your van with tools and writing ‘electrician’ on it, and doing work in your own house.

 

[HappyHacker]

As an electrician I have seen good work done by DIYers and dangerous work done by "electricians". The problem is that electricity and the way we use it is very safe while every thing is OK but the problems start if there is a problem and the installation is inadequate for the problem situation. Have a look for Emma Shaw Inquest to see what I mean and that installation was done by "professionals".

I have seen accessible bare live conductors, bolts used instead of fuses even a working fuse wrapped with foil as obviously it was being overloaded and an installation without any earth of any sort. All working fine until something goes wrong.

So as a professional I am reluctant to offer advice over the internet as I have not seen and tested the installation and picked up on the warning signs that would indicate a problem.

One bit of advice i will give is to use H07RNF for the flex to connect equipment, in my view it is better than SY for that purpose, although one of my machines does use SY. One of the problems with SY is that the braid, it's not armour, should be earthed and usually isn't. I believe SY was designed for control panel interconnects where it would be fastened and protected rather than being dragged across a floor.

 

[guineafowl21]

As an electrician I have seen good work done by DIYers and dangerous work done by "electricians". The problem is that electricity and the way we use it is very safe while every thing is OK but the problems start if there is a problem and the installation is inadequate for the problem situation. Have a look for Emma Shaw Inquest to see what I mean and that installation was done by "professionals".

+1 Anyone can wire up a device and get it working, it’s the circuit protection (lack of) that’s the ticking time bomb. It takes a tiny amount of power to kill a human, many orders of magnitude less than is useful for an appliance. Electrical outlets must therefore remain potentially lethal. It’s only the layers of protection, and testing, that make them relatively safe.

I’ve read brief accounts of the Emma Shaw inquest. To my mind, the failure there was not burying cables 50mm, or having them outside prescribed zones, and then not protecting them with an RCD. The metal studwork should also have been earthed. Lack of IR testing, too. Every layer of protection was breached.