16 Amp supply for bandsaw

[steve158]

I'm happy to change the device myself as a competent person

What do you mean by a competent person? It seems to me that you are going to do something without understanding the potential of such an action. It is unlikely that your shed is on a ring final circuit as you state.

 

[XH558]

What do you mean by a competent person? It seems to me that you are going to do something without understanding the potential of such an action. It is unlikely that your shed is on a ring final circuit as you state.

I'm very grateful for your concern as to my levels of competence. Most touching.

My shed, it is on a ring as I did the installation. First and second fix. You are most welcome to come and inspect it if you wish.

Should you desire I can post a copy of the IEE Certification too.

 

[XH558]

It's the trade name that MK (purveyor of fine plugs and whatnot) used when they launched their range of CEE17 (now IEC60309) plugs and sockets in the UK...

I have always called them "CEE-Form" rather than "Commando", because the latter seems oddly incongruous.

My days of going commando are few and far between.

 

[steve158]

I trained as a building surveyor. Part of that was building services including electrical services in both 3 phase and single phase. Heating, gas, oil and solid fuel. Commercial and domestic lighting machinery calculating power factor corrections. I have designed extensions to buildings in Conservation Areas, adaptations for those with disabilities including hoist systems.

As for my shed, it IS on a ring as I did the installation. First and second fix.

Oh I see, I get concerned when I see simplistic approaches such as changing the mcb for a higher rating. I incorrectly assumed that you were not aware that this would be notifiable work as required by Part P.

 

[Inspector]

I'm a little curious as to why you guys have what looks to me to be odd steps in the amperage differences of your circuits? I have 15, 20 and 30 amp plugs in my shop and garage for the 220V, not counting the 110V stuff. You have 13 and 16. What is above them?

Pete

 

[Jelly]

I'm very grateful for your concern as to my levels of competence. Most touching.

I much prefer the HSE's "Suitability Qualified and Experienced" over the BR's "Competent" for this very reason...

The HSE wording is nearly impossible to misinterpret because it's never going to be used outside that specific context.

I'm a little curious as to why you guys have what looks to me to be odd steps in the amperage differences of your circuits? I have 15, 20 and 30 amp plugs in my shop and garage for the 220V, not counting the 110V stuff. You have 13 and 16. What is above them?

Pete

MCB's come in 1, 3, 6, 10, 16, 20, 30, 40, 50, and 100A ratings

240V Plugs come in 3, 5, 13, 15, 16 and 32A sizes, but generally only 13A are used in domestic applications, 5A are used for commercial lamp installations which as all switched togther, and 16A is used for some commercial equipment and outside power to caravans and camper vans, I've never seen a 32A installed in real life only in catalogues.

480v plugs come in 16, 32, and 64A sizes, and are generally commercial only.

 

[Inspector]

MCB means mains circuit breaker? I can't recall ever seeing a circuit breaker under 15 amp, even for 110V. Our systems are very much different. So would your 13 and 15 amp plugs be protected by a 16 amp breaker, and the 16 amp plug be protected by a 20 amp breaker?

I'll add my 5hp motors are on the 30 amp breakers in the shop and garage, a 30 amp would be for a dryer in the laundry and a kitchen stove would be on a 40 amp. Domestic hot water is on one or the other, I'm not sure as I haven't had one in decades. Heat and cook with natural gas in this place.

Pete

 

[porker]

MCB is Miniature Circuit Breaker. We use 230V for domestic but lower voltage 110V is used for things like site tools for safety reasons and industrially we use 3 phase 400-415V (domestic is just one of these phases)

Our domestic plug tops are fused unlike a lot of other countries usually at 13A but as above can be lower (5A or 3A) depending on the appliance.

16A sockets are not fused themselves so are protected by their own breaker. They are only really used for machinery and most homes wouldn't have them.

We also use this slightly odd concept of a ring final circuit which is a loop from and back to the fuseboard which allows 32A MCB. Wiring with radials is becoming more popular which is rated at 16A or 20A. Lighting is usually on 6A. Cookers, Showers are typically at 40A. Lots of exceptions to this though depending on application. Won't even get into earthing.

 

[Jelly]

lower voltage 110V is used for things like site tools for safety reasons

If I recall correctly, our 110v tools actually use 55v split phase fed from an isolation transformer with center tapped neutral (not dissimilar to US 240V domestic supplies).

This reduces the classification to Extremely Low Voltage, reducing the complexity of protective systems required for use in wet environments, as the system is considered inherently safe(-er, if you got a fault allowing you to touch both phases, that would still be a seriously bad day).

 

[Sideways]

The UK style "ring main" aka "ring final circuit" is not common beyond the UK. Most / all of continental europe uses unfused domestic plugs, typically rated 16A on radial circuits protected by miniature / moulded circuit breaker.
The UK ring I believe is a legacy of WW2 era copper shortages. The ring is wired in 2.5mm sq copper with a 1.5mm earth wire. Multiple sockets are distributed around the ring which typically runs around a floor of a domestic dwelling, fed from both ends from the same 30 or 32A fuse or breaker. Fine as designed but if the ring is broken, the 2.5mm conductors are rated around 20A so a low grade overload of long duration does pose a risk of overheating the cables.

 

[Bodger7]

After reading all the advice offered I decided to contact a local electricians firm. They got one of their electricians to 'phone me and after explaining the set up in my workshop his advice was pretty much the same as that given by Sideways. So I now have a 2 metre extension lead with a Commando socket on one end and a 13 amp plug on the other. The bandsaw arrives Tuesday so I will find out then whether that will be sufficient.

 

[julianf]

Amps and voltage etc are not always as clear as they would seem.

If you have kit on the end of a long wire, the voltage drop means increased current draw, and blown fuses. The same unit may work absolutely fine on a different circuit.

Breakers are as simple as just a number either. My table saw would happily carry on running off a 13a fuse. But needs a 16a C curve breaker to deal with the start up current. C curve is what you might call "slow blow".

What would i do in the OPs situation? Put a 13a plug on it and plug it in. See what happens. Worst case its going to blow the fuse, as, well, that's what fuses are there for. If it works, job done. If it doesn't, very little lost (its not going to kill the machine, the operator, the wall wiring, or anything else - again, that's the whole reason for the fuse)

If it does not work, just replace the fuse with a nail.

The next move would be to install a 16A socket on the wall, with a dedicated breaker, but that's a bit more involved.


(the comment about replacing the fuse with a nail was a joke, so if you got agitated, please relax)

 

[Inspector]

Julianf. We are woodworkers! It should be a proper brass screw with the head aligned vertically.

Pete

PS. The screw remark is also a joke.

 

[Spectric]

We also use this slightly odd concept of a ring final circuit which is a loop from and back to the fuseboard which allows 32A MCB. Wiring with radials is becoming more popular which is rated at 16A or 20A. Lighting is usually on 6A. Cookers, Showers are typically at 40A. Lots of exceptions to this though depending on application. Won't even get into earthing.

The ring main should be consigned into the history books, and there is no usually! Each circuit from a distribution board should be designed to handle the required load and cable chosen based on current, volt drop and method of instalation. 2.5mm radial on a 20 amp device or a 4.0mm radial on a 32 amp device. The protective device is then selected to ensure that circuit wiring is protected under fault conditions. Yes I have seen 16 amp sockets wired into a ring main but this is a no no as there is no protection. Also you cannot just change the type of protective device. A 16 amp type B will need 3 to 5 times the working current to trip (48 to 80 amps). A 16 amp type C requires 5 to 10 times the working current to trip(80 to 160 amps). Is the loop impedance of that circuit low enough to allow the increased fault current required, it could well have been marginal before the change. Also remember that the total loop impedance is not just that of the wiring within your shed, it is the whole circuit back to the local sub, before modern testers it was refered to as external impedance Zo. Providing the fault is L to N then earthing is less of an issue but L to the conductive parts of a machine and then you realise how important the means of earthing can become. Examples here are people using armoured cable, incorrectly glanded or placing to much reliance on the armour for the CPC, run the earth as a core within the cable and that can make life easier. With large industrial supplies we used to run seperate CPC's along with the armoured cables, ie a 95mm cpc with a 185mm 4 core.

 

[Peri]

After reading all the advice offered I decided to contact a local electricians firm. They got one of their electricians to 'phone me and after explaining the set up in my workshop his advice was pretty much the same as that given by Sideways. So I now have a 2 metre extension lead with a Commando socket on one end and a 13 amp plug on the other. The bandsaw arrives Tuesday so I will find out then whether that will be sufficient.

I may be in a similiar situation soon - how did you get on?

 

[Farm Labourer]

As I type this, I have Gary the Spark (Part P) in the workshop installing 20A supplies for a new P/T and one for my 16A extractor, which as a very naughty boy, I've been running out of a 13A socket. He has taken the existing 50A supply into the building which has it's own ring, protected by a board and MCBs and jumped that to a dedicated unit that has three new 20A rated breakers. One spare and one each for P/T and extractor. He has run armoured cable to two rotary switches. The machines connect straight into the rotary switches. Or rather, when the P/T gets here it will as it is supplied with only 500mm of cable and that will be a new challenge (as it sits in the middle of the 'shop)! Total cost not finalised but I'm not expecting change out of £250. Parts alone are nearly £100. The risk of a fire and the ensuing issues with a claim once it became apparent that it was probably caused by drawing too much load caused me to go down this road. Having spent a King's ransome on a new P/T - the extra wonga to provide it with safe power was hardly worth worrying about. I have a 30A supply for a welder and was going to go down the route of using that and splitting it for each device but was concerned that the P/T would not start if the extractor was running, so just bit the bullet. I must own the only farm in E Anglia without 3 Phase - which does grip me!

 

[Bodger7]

I may be in a similiar situation soon - how did you get on?

Hi Steve
I stuck with the 2 metre extension lead for a week or two but then realised that I had a similarly constructed lead for our caravan that is about 30 centimetres long so I used that instead as there is less lead to get in the way. The bandsaw has had constant use since it arrived and there hasn't been a single problem with this arrangement. For what it is worth my whole workshop works off a spur into a household ring main and I know that I should alter this but my only problem has for some reason come from a small dust extractor that is used infrequently. The mini lead from a caravan supplies shop is a cheap way to test whether this will work for you. Best of luck.
Peter

 

[Peri]

Thanks Pete.
My workshop runs off an extension lead - not the greatest solution, but I live in rented property and my workshop is about 40 feet away, on the other side of a communal car park. Upgrading the electrics isn't possible.

Admittedly, in the winter with the fan heater, dust extractor and tablesaw going the plug can get a tad warm, but I've never blown any fuses yet.

I'm considering upgrading my TS, and the Itech model I'm looking at doesn't state a 16amp supply, but the next model up, with the same motor (2.2kw), does.

 

[Spectric]

I'm considering upgrading my TS, and the Itech model I'm looking at doesn't state a 16amp supply, but the next model up, with the same motor (2.2kw), does.

My TS has a 2.2Kw motor and runs from a 13 amp plug, the same as my bandsaw but there is a lot more to supplying a load than just amps. The length of a cable run introduces a volt drop which will effect the current you can pull, your supply is at the end of an extension lead and protected by a 13 amp fuse which will more than likely not be capable of running your loads. There is a solution but not when you have to cross a public space, can you not move the saw closer to your house when it is needed, I know it is weather dependant but there are others in a similiar position. Not knowing what you are cutting, but let's assume sheet goods then rather than the table saw have you thought about a tracksaw! With a couple of tressles it will give you a Portable solution for less cost.

 

[JobandKnock]

My TS has a 2.2Kw motor and runs from a 13 amp plug, the same as my bandsaw but there is a lot more to supplying a load than just amps. The length of a cable run introduces a volt drop which will effect the current you can pull, your supply is at the end of an extension lead and protected by a 13 amp fuse which will more than likely not be capable of running your loads.

I'll echo Spectric's comments about cable run lengths. As someone who spends a disproportionate amount of his working life out on construction sites I have experienced loads of issues with extension cables which were too long for the machinery we want to run on them. All our cables are on what we refer to as BS.4343 connectors (referred to elsewhere in this thread as CEE type 17 or Commando, although I've never heard a site sparky or HSE inspector refer to them as such) and the only way I've ever found to get my deWalt DW745 portable site saw or my 14cfm compressor to work consistently is to use the 32A sockets on the transformers (which have very large pins in comparison with the 16A ones, which in turn are larger than the 13A square pins on a domestic plug top) and the thickest single extension cable I can lay my hands on. Cheaper extension cables only have 1.5mm cross section wire in them. Heavy duty ones should have 2.5mm cross section and even thet can sometimes be too thin to start an 1800 watt (universal motor) saw at the end of a 15 metre (50ft) cable run. I first adopted a 4mm cross section cable when I bought the DW745 which fixed the issue, but I then needed to go to a 6mm cable a couple of years ago when I acquired the compressor (2.2kW induction motor) because the 4mm cable wouldn't always work. The circuits these go onto are generally just 20A MCB protected, so it isn't the MCB which is the limiting factor, it's the voltage drop caused by trying to use too thin a bit of "electric string". The downside of going to a 6mm cable, though, is that is set me back about £85 at the time, and it is also very "nickable" so it always has to be secured and locked up when not in use.