Looking to extend power to a new workshop and hoping to take a feed from an existing supply in the garage. The garage is supplied from a CU in the main property via armoured 10mm cable to a small CU with a 63amp trip running a 6amp lighting circuit and 16amp socket circuit. My intention is to upgrade the garage CU so I can add additional breakers and feed the new workshop from that and recycle the small CU into the new workshop. While having a look at how its setup at present I noticed that on the CU in the property the garage breaker is only 16amp, I was expecting to find at least a 32amp breaker. My question is can this be correct? If not, what would people suggest is the correct way it should be done? Cheers
that breaker may be offset to the cable size due to distance between the house and the garage also how far from the garage is the new workshop (and how much power is that going to need) added to the garage needs can the current 10mm supply all that?
also make sure that aint a plastic cu in the garage as if it is yes you can re use it but you will need to build a fire prof cupboard to inclose it with in your work shop with a door big enough to allow for repairs to the cu without needing to remove the cupboard (stupid amd 3)
Distance between house and garage is about 3.5m, distance to new workshop is about 10m. Requirement in the workshop is for 7 double sockets and a basic lighting circuit running two strip lights. I have a jointer/thicknesser and a table saw (single phase) so should they be better off on separate breakers? But recycling the old CU may not be an option as it is plastic and is not expandable. Only one machine will be running at a time. My electrician has moved to Oz and before I found him I had some proper cowboys on previous properties, he sorted everything for me which ended up meaning I paid twice but now without him I don't want to go through it all again. I would prefer to understand whats required so I can be confident that the person doing the job will be doing it correctly. Cheers
no prob with that and if the sockets are run in a ring there should be no prob in your new workshop im sure some of the time serverd sparks can help with the distance calcs (maths has never been my strong suit) and dont have the tables to hand either (best to get your self all up on what you need so you dont get taken for a mug) that sounds like that cable was over rated for what it is running atm (prob to allow for upgrading) and sounds ok for extending but a spark will know better
Yes, in the garage CU it's a CPN RC263/030 63a 30mA Double Pole RCD and the one at the property CU is a Proteus B16 Single Pole MCB, that's the bit that is confusing me. I would have thought the one at the house would be of a higher rating, similar to the 32a RCBO I have on the unit running to a patio heater. The one time power tripped due to a dodgy drill it bypassed the RCD and tripped at the main CU. Cheers
that is due to trip times (just because two rcds or mcb trips work to trip at the same mili amps to trip the speed can differ greatly)
also the same two trips (mcb or rcd) can trip in a total reverse for a netural earth fault vs a live earth fault (ie trip A is faster than trip B for a live to earth fault where with a netrual to earth fault trip B is faster than trip A)
The CPN RC263/030 63a 30mA Double Pole RCD in the garage is NOT a over current circuit breaker, it is just an RCD. The 63A rating is telling you what it can safely carry and break. Te overcurrent protection is provided by the 16A at teh house and the local ones in teh garage CU. Your electrician should be able to advise on uprating te 16A to 32, 40 or 50A - whichever he considers appropriate.
I'd have said the best way to do it would be to Henley block from your incoming supply into a separate fused switch unit dedicated to power your workshop. This would travel via an SWA cable to your workshop and terminate into a dedicated mini consumer unit with RCD protected 32Amp for ring finals and a 6Amp for lighting radial. You might as well use a metal CU in the garage as SWA glands will bolt-up very nicely to a metal housing vs plastic, i find the metal housings far nicer to work with, always have done so i am very pleased to see the new regs change. It is as simple as that really, no need to touch your domestic consumer unit although it can be done that way to save money. Choice of SWA cable you can use is either two core and the armour is your earth or use 3 phase where you utilise the third core of the cable as the earth along with the armour, much better on longer runs. Make it neat and tidy too, I had a customer call in Building Control for some other issue after i had done my job last month and the inspector had everything tested due to some cowboy knocking down a wall without supporting the ceiling. The inspector was incredibly impressed by the neat tidy quality work i had done on the wiring he asked to take pictures so he could use in his presentation of how things should be done. One thing must be said as rule of thumb for the DIY person is that if an existing installation has a rated breaker installed you must not change it to a larger rating. There is a reason that rating was selected, you can go down in rating but NOT up... If you want to go up in current rating you need a professional re-wire unless you completely know what you are doing.
The general consensus is if the detached building going up in flames will not affect the dwelling then you can fit plastic. If not sure, fit metal
The trouble with correctly rated over loads (fuses to you people) is that they keep getting in the way and tripping. As for RCDs, well do NOT get me started. Best thing is to use 'the force' and ignore all good practice and the regulations and do what Dickins you feel like. Go gadget sparky.......
Billy, if you want to talk down and use your "pro" language, get it right. It's an overload protective device. An "overload" would typically describe a motors thermal overload fitted in a DOL or similar starter. You say fuses, then say they get in the way by tripping. If you're going to be rude, at lease be correct.
Forums
Facebook
Twitter
You Tube
Instagram
Shop