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Arbalist:
I'll get an electrician in to hook things up but I'll probably do the wiring myself in my new shed. Thought I'd need just a simple two way consumer unit until I started looking, now I'm getting confused. Too many choices, can anyone help me out!

http://www.screwfix.com/p/mk-sentry-4-way-rcd-garage-consumer-unit/33248

http://www.screwfix.com/p/lap-3-way-fully-populated-rcd-garage-consumer-unit/29910

http://www.screwfix.com/p/mk-metal-garage-kit/14107

I'll be putting in four fluorescent tubes for lighting and a simple ring of metal clad sockets with the wiring in plastic conduit. Think six doubles should do it.

lordedmond:
I have the first one installed , my next statement is qualified with me being a time served sparks when I left school at 15 that was 51 years ago I am not a house brasher but more industrial leanings

They all suffer with one drawback with the RCD on the incomer if you have a fault that trips the RCD it all goes off and you are in the dark , you need a unit that has a normal breaker for the incoming and the RCD on the ring main cct.

Now comes the crunch with RCD and workshops that we use it's the VFD drives that have delta filters on them the will ,do trip RCD with the delta caps passing enough to earth to trip it , not all do it

My Myford does it and I have tested it carefully and it ok ,it's the filter for the odd order harmonics that cause it to fault the RCD when you switch off the lathe.

Now you may ask what I have done to sort it ,I have disabled the RCD my choice ,not recommended but I have things earthed correctly and I am confident that I am safe , I have also put in a copper earth rod local to the WS and I know this is good because I have tested it and it's less than 0.1 ohm

If you are not sure please be safe and consult a qualified sparks about this but your light must not be controlled from a RCD the must stay on when the ring main faults

Remember you cannot see it ,smell it but by ek you can feel it

Stuart

Arbalist:
I kind of assumed that there would only be an RCD on the circuit for the sockets, as you say it's daft to have it on a lighting circuit. I'll have to look out for that!

lordedmond:
In the first link the mob on the left is the RCD that is the incomer the other two may be one 5amp and one16 amp not sure

Therefore the RCD controls everything


FWIW that's why in a domestic situation the consumer units are split one half has the RCD and the other not, you tend to put the lights and freezer/fridges on the non RCD side and all other on the RCD controlled side

I am old fashioned and a firm believer of earth bonding of all things that you can touch eg. Lathe and mill less than the span of your arms must be bonded with 16 mm bonding cable that way if one gets hot there will be no difference in the potential between them and therefore no risk.

With electric drill 250volt and mowers just use a RCD plug or dedicated RCD socket in case you cutt the cable
Stuart

Your best bet is to get a small consumer unit and fit it out as you require normal MCB for light and a RCD for your sockets and another normal one for the ring that has your machine on.
But do not forget to bond them together and any radiators that my be in the workshop, a rule if you can touch both pieces of equipment with each hand bond it

hermetic:
Hi Arbalist,
  If you get a plain consumer unit with a 60A incomer (formerly known as the main switch) and then fit a 32A RCBO (residual current breaker overload) to protect the ring main and the standard 6A MCB to protect the lighting. As has been said above, if you are using a VFD or inverter drive type device you will have to use an RCBO which is suitable type for use with this equipment. Unfortunately nuisance tripping of RCD's and RCBO's by equipment using capacitors (vfd's etc) which filter transient voltages to earth is an ingoing problem to which there seems to be no 100% cure at the moment. At least this means your lights won't go out. I am lucky, I have three phase in my workshop, but still use fuse protection. There is nothing wrong with this as long as all the machines are properly earthed, and the earth is good. The RCD monitors the current flowing in the live and the return(neutral) or the phases in three phase systems, and trips if there is any imbalance in the readings. This still requires the machines to be earthed properly, as if it is not it will not trip untill someone touches the machine and provides a "path to earth" for the fault current. I am telling you all this to emphasise the importance of earthing all metal machines even if you are using an RCD.
Phil.

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