i ve noticed a few mentions of 240v machinery tripping 13 amp circuits and as i'm just at the stage to start wiring my new workshop,would it be advisable to install heavier 16 amp circuits for these machines.
workshop power supply
- Thread starter david.tamlaght
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ajs
Established Member
Not a bad idea to get a couple in. Alternatively get the cable laid at the same time as the ring circuit but leave it as bare cable until it is needed, the additional labour and cost of cable is fairly low if cables are already being put in. The breaker and socket can easily be fitted later when a circuit is needed. If you need a new consumer unit now ensure the new one has a couple of spare spaces to accommodate the 16A circuits in due course.
sawtooth-9
Established Member
Always good to provide more power than you expect to use.
You have not told us what machines you want to run, so it's difficult to advise.
For a real workshop, I would run some heavy cable from your mains ( at least 6 mm square = about 36 amps ) to a sub board in your workshop. If you can do this from two phases, you can get some real power for most single phase machinery.
If you need more than that, go to a three phase supply - 30 amps per phase equates to close to 100 amps at 240 volts.
I run power from a three phase generator producing 32 amps per phase.
If you read those mentions very carefully, you will determine how and particularly when the tripping occurs. Nuisance tripping generally occurs in the first half second after you have switched the machine on. Why is this? Because a motor is an inductive load and it draws a huge current for a a short period of time after initial energising. Have a read up on 'circuit breaker tripping curve', e.g. c3controls Suggest to your electrician that a D-rated breaker is fitted where appropriate. Simply upping the circuit capacity is not a reliable way to solve the problem (a motor that draws nominal 10A might still trip a 16A circuit on startup if the 16A breaker fitted is a B-curve).
I'm totally blind to all things electric.If i don't understand something ,i leave it to someone who does.
I take it from the replies that i would need 2 circuits then. 13a for normal power tools and 16a for machinery (350 sabre/tp107/lathe/dewalt radial arm)
i'll mention these replies to my sparkie ,especially that D rated breaker.
the line from my house was laid many years ago to my picture framing workshop and was put in to accommodate future machines so will be at least 6mm or maybe 10 .don't remember tbh
The only thing in the framing shop that requires any great power is my HGP260 vacuum press and have never had it trip off on the 2.5 circuit .
The whole system is going in new so cost isn't really an issue .Whatever it needs will go in at the start and be done with it .
Thanks to all for the advice
I take it from the replies that i would need 2 circuits then. 13a for normal power tools and 16a for machinery (350 sabre/tp107/lathe/dewalt radial arm)
i'll mention these replies to my sparkie ,especially that D rated breaker.
the line from my house was laid many years ago to my picture framing workshop and was put in to accommodate future machines so will be at least 6mm or maybe 10 .don't remember tbh
The only thing in the framing shop that requires any great power is my HGP260 vacuum press and have never had it trip off on the 2.5 circuit .
The whole system is going in new so cost isn't really an issue .Whatever it needs will go in at the start and be done with it .
Thanks to all for the advice
Something i ve just noticed on an associated thread .
Is it not possible to install a curcuit of 4 blue outlets on 16 amp with the appropriate breaker at the board or does each outlet need its own feed and breaker direct from the board .
The circuit seems to be a no no going by that other thread
Is it not possible to install a curcuit of 4 blue outlets on 16 amp with the appropriate breaker at the board or does each outlet need its own feed and breaker direct from the board .
The circuit seems to be a no no going by that other thread
ajs
Established Member
Each one is on its own circuit back to the consumer unit. They don't use domestic style ring circuits. This is one of the perennial fudges proposed here and elsewhere, they can't be wired to a ring circuit even though the cable is rated for the power.
As sawtooth-9 said a secondary consumer unit actually in the shop isn't a bad idea. It can simplify some requirements such as isolation within sight of the socket, also if additional circuits need to be added later they only need wiring back to that instead of the main unit.
You have not stated the type of supply to the property, the cable sizing to your workshop or the construction of your workshop, ie is it metal framed. Also don't use historical ring mains in your workshop, these days we fit radials and preferably run individual wires in conduit. Use 2.5mm CSA on a 20 amp protective device or 4.0mm CSA on a 32 amp protective device. With twin and earth the CPC is smaller, only 1.5mm in a 2.5mm cable.
Each socket should technically be on it's own circuit protected by it's own device, this is because if they were all on the same circuit then it is possible that the loads would pull excessive current that is not high enough to disconnect the protective device but would result in an overload current. Saying this I have seen this done in a domestic workshop enviroment where there is only a single person working and the argument was that they could only ever use one machine at a time.
You must have a distribution board in your workshop, it is the only way to provide individual circuits with a protective device and I would say that as this all involves design then it is notifiable to your local building control, for this you will need the installation certified which will require the proper test equipment so my advice would be to get a qualified electrician to undertake the work, NOT a domestic installer who is really a glorified electricians mate.
The reason why is because with a 13 amp socket there is a fuse in the plug, fitting a 16 amp socket would mean that anything pluged into that 16 amp socket would only be fused at the board by a 32 amp device.
Thanks.
Its an all timber constructed shop.
the supply is either 6 or 10mm .not sure
The spark doing it is a fully certified guy with great experience and knowledge so it will be done properly .
I was just getting info as to the special requirments of running machines to guard against any future issues like tripping at start up .
Think i ve got my head around it now as to whats needed .
With a decent sparky then you will get a safe job, he will know about fitting type C protective devices for any loads that have a high inrush current and sizing wiring accordingly so good luck and once up and running let us know what you get upto in your new workshop. There is a wealth of good info around here, my professional background was not woodworking, EC&I engineer and software but my woodworking has really progressed with the info from around here, downside is the bank balance because of some really good tool reviews.
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Drifter2406
Established Member
Mine is fitted with a separate consumer unit for the Cabin off of my household one and another one in the Cabin with 12mm armored cable 150ft ish long, all running from a 16A supply, all my machines are about 3-3.5 HP and as I don't use all of them all at the time it has been fine for over 10 years.
You may have a separate circuit for lighting anyway, so you might just need a slightly bigger consumer unit.
It's also handy to have a circuit for low-power devices e.g. workbench things, battery chargers, laptops etc., so these don't go off if the "big machines" circuits trip, or you've switched them off for safety.
If starting again, I would also like a big rotary switch to turn the big machines on/off. Maybe dust collection would be on a separate switched circuit.
It's also handy to have a circuit for low-power devices e.g. workbench things, battery chargers, laptops etc., so these don't go off if the "big machines" circuits trip, or you've switched them off for safety.
If starting again, I would also like a big rotary switch to turn the big machines on/off. Maybe dust collection would be on a separate switched circuit.
I have posted about mine on here before, with a new install of power we had:
- white plugs for normal (charging / air filters / etc.) including a number with usb sockets
- red plugs for machinery, separately wired
- blue plugs for fridges and freezers (we have the workshop in the old garage and then a further 6m extension on the front for storage / fridges / freezers / etc.
All the red plugs are wired through a rotary switch - so regardless of any machine plug being on or off, I can turn off all machines with one switch - leaving he air filters / battery charging / wine fridge / etc. still running... Used anytime we have children of a certain age come over - very useful...
- white plugs for normal (charging / air filters / etc.) including a number with usb sockets
- red plugs for machinery, separately wired
- blue plugs for fridges and freezers (we have the workshop in the old garage and then a further 6m extension on the front for storage / fridges / freezers / etc.
All the red plugs are wired through a rotary switch - so regardless of any machine plug being on or off, I can turn off all machines with one switch - leaving he air filters / battery charging / wine fridge / etc. still running... Used anytime we have children of a certain age come over - very useful...
so the rotary switch isolates the whole 16a board .is that correct as i intend fitting 4 blue i6a sockets ,all wirded individually with 4 trips at the CU .sounds like a good idea and the usb plugs on the 13a plug circuit too.
I don't have any specific 16amp fuses / boards... so all mine are wired on rings
the red / power tools circuit, comes out of the fuse board and into the rotary switch so that you only turn off that circuit - not the others - if you have it before the board it would then turn off the whole board and that could be fine for you if all your 16amp options are running from one board and the rest from another, but my board runs all the circuits, so I have to isolate post board not pre board...
at a logic level there is no issue putting it before the board, but I have no idea what the electrical significance of that might be - would need to check.
mine was all done by a professional company and signed off, so i told them what I wanted at a conceptual level and let them do the electric bits!
If you have a 16 amp socket connected to the ring, this contravenes the regs because there is no protective device between the 32 amp side and the 16 amp potential load, in other words the cable on the 16 amp side would not handle the potential fault current needed to disconnect a type B 32 amp protective device let alone a type C if one has been fitted.
https://www.ukworkshop.co.uk/threads/16amp-socket-advice.127835/
Inspector
Nyuck, Nyuck, Nyuck!
You guys do things differently than on this side of the earth so lots of what is said flies right on by me. When I was making my shop I told the electrician what I would need running at any one time and he set it up accordingly. I told him maximum a 5hp air compressor (it is left on so never know when it will kick in), 5hp dust collector, the 3hp or the 5hp table saw and possibly a 110v, 20amp planer/jointer (planer/thicknesser) and the lights. He set up a 100 amp sub-panel for shop and garage off the 200 amp main panel for the house. 110v, 20amp and 220V, 20 and 30 amp circuits on each wall on their own circuits. I have never tripped a breaker in the 6 years being here and don't have to walk more than a few feet to reach a plug. I suggest you work with the electrician to design and map out your wiring and to put the plugs up the wall so that a sheet of plywood can lean on it and not cover the plugs. Mine are not quite high enough and that plug is always the most convenient one. Also a weatherproof plug or two on the outside of the shop is handy when you want to work outdoors.
Pete
Pete
Mutley Racers
Established Member
Hi. My garage workshop sounds similar to this with fridges etc running off of the same supply. I am looking at getting a consumer unit put in. Can you link to your post please.
