Hedge trimmers, generators and invertors

Hello -
I have a relative who needs to be able to trim about 400 metres of tough
hedgerow once a year. At present they have a light but sturdy electric hedge
trimmer, but the cable obviously isn't long enough. The furthest bit of
hedge is 200 metres from a power socket, I can think of 4 options, in
descending order of sensibleness:
1) Buy a petrol hedge trimmer, maybe £200. With this size of job, I guess it
would be a fairly hefty one, so there would be safety issues and also and
presumably a learning period while arm muscles were built up.
2) Buy a small petrol generator (maybe less than £200), and run the electric
trimmer from this. The generator might be useful for other tasks, and we
could carry on using the nice light electric trimmer.
3) All of the hedgerow is accessible by car, so we could buy an inverter
(maybe less than £200) and run the electric trimmer from that. The inverter
might be useful for other things. Time spent setting up the wires and stuff
would not be a problem, as it would only happen once a year.
4) Work out what sort of cable would be needed to run the electric hedge
trimmer 200 metres away from the house. It would have to be hefty to reduce
voltage drop and there are probably safety issues to look into.
Should we just take the conventional option of a petrol hedgetrimmer?
Reply to
Pay a local farmer to do it with his tractor and trimmer probably only take an hour so
Reply to
Four stroke 800w generator £140 inc from Costco. You would pay that for a petrol trimmer and it will be useful in the forthcoming power cuts, if you can afford the fuel.
Reply to
I think that this would be your best option.
Not so good as small generators do not like sudden transient reactive loads imposed on them, especially from motors.
Same as above.
Big, very fat cable and awkward.
Reply to
There's a fifth option, which is an electric trimmer which takes rechargeable batteries.... I haven't a clue how many batteries you'd need to do 400m - maybe too many? But worth considering before ruling out, anyway!
Reply to
Yes, I hadn't really considered that. I don't mind doing the hedge over several days, with recharging sessions in between. My main concern would be whether a rechargable trimmer would be designed for a heavy-duty task like this. The hedgerow is a mixture of various knarled, spiny and woody plants.
Reply to
We have both rechargeable (Bosch) and (heavy duty - Viking) electric hedge trimmers. My wife uses the rechargeable one for her flower garden hedges - ideal for light- duty stuff. I use the electric trimmer for my hedges - much thicker stuff to trim. The rechargeable trimmer would be a waste of time on my hedges.
400m of "various knarled, spiny and woody plants". I'd forget rechargeable.
Reply to
Hugh Jampton
Simon formulated on Monday :
That is a none starter - the rechargeables are only suitable for the very lightest of duties.
The car battery plus inverter solution would soon flatten the car battery and most inverters are not up to running heavily loaded motor loads. Assuming a suitable inverter and further assuming 400w motor, a single 120amp hour leisure battery (better suited to this type of use) might run it it for 1.5 hours to the half discharged point of the battery - so not much use without a whole series of batteries to go at, plus a good charger.
I would suggest a generator or a series of new outdoor sockets mounted every 50 yards, but the latter would be a long term investment. Not sure what a robust mains hedge trimmer might draw, but a 3core 2.5mm armoured should cover it I think.
Reply to
Harry Bloomfield
In message , Hugh Jampton writes
Agreed. I have a some Viking kit, a standard 600 and a long reach 700 and I would be reluctant to tackle a 400 metre woody hedge with them. Someone suggested paying someone to do it which could be an excellent idea, however, even if you can find a local farmer or itinerant contractor with a tractor mounted flail, who can do the job as an adjunct to another local cut, it is unlikely to be an inexpensive and you could pay the same over 3 years that a petrol trimmer would cost. You should be able to pick up reasonable Stihl or Husqvana petrol kit (minimum 60 cms cutter) for around £250 if the 400m hedge and other stuff around your garden is all you want it for.
Reply to
First option must be to compare the cost of having someone do the job for them, mind 400m could take a couple of mandays.
I'd do this for a hedge this long simply because a petrol hedge trimmer will put a couple of kW of power in your hand and cut 75cms in each sweep but as you say they make the arms ache, electric ones seem to be about 600W and 55cm but are so slow. I generally use an old Stihl hl75 but keep a 20 year old robin for close work. keep the heads oiled, adjusted and sharp.
As my little 2 stroke generator will handsomely run a 750W angle grinder I'm sure it will run a domestic hedge cutter and it only cost 60quid so this may be worthwhile.
Reply to
Hire a big genny-on-a-trailer once a year. Easier to keep moving it forward a few dozen yards at a time than having to drag a 'portable' genny.
Reply to
In article ,
When filming on location we often get cable runs of that order - and run fairly high power lamps. The cable the sparks use for this sort of thing is 2.5mm flex - and I'd say it will be fine for this relatively low load. It's too big to fit ordinary 13 amp fittings so you'd need to use these plugs and line sockets :-
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13 amp short tails at either end using 1.5mm flex. I'd also have an RCD plug on the trimmer.
This is the cable:-
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But you're probably looking at about 250 quid - just for an extension lead. ;-)
Reply to
Dave Plowman (News)
Lightweight hedge trimmer is probably 3A (720W), but it may be wiser to consider 4A re load/stall etc.
Voltage drop... o 2.5mm - 18mV/A/m - 200m @ 18mV @ 3A = 10.8V drop o 2.5mm - 18mV/A/m - 200m @ 18mV @ 4A = 14.4V drop o 4.0mm - 11mV/A/m - 200m @ 11mV @ 3A = 6.6V drop o 4.0mm - 11mV/A/m - 200m @ 11mV @ 4A = 8.8V drop
Whilst not "fixed wiring", 525-01-02 limits voltage drop to 4% of 9.2V assuming Uo is 230V (it may be lower or it may be higher which would be to your benefit).
Earth Fault Loop Impedance... o Socket disconnect time needs to be 0.4sec, 413-02-09 o Assuming TN-S supply (Ze 0.80ohm) vs TN-C-S (0.35ohm) o Assuming 70oC re black cable in direct summer sunlight o R1+R2 for 2.5mm flex Phase & CPC is 7.41+7.41mohm/m ---- R1+R2 = (7.41+7.41) * 200 * 1.20 = 3.56ohm o R1+R2 for 4.0mm flex Phase & CPC is 4.61+4.61mohm/m ---- R1+R2 = (4.61+4.61) * 200 * 1.20 = 2.22ohm o Earth Fault Loop Impedance Zs = Ze + (R1+R2) ---- Zs-2.5mm = 0.80 + (3.56) = 4.36ohm at 70oC ---- Zs-4.0mm = 0.80 + (2.22) = 3.02ohm at 70oC
Verify CPD ops under calculated Earth Fault Loop Impedance, Zs o Assuming house socket is fed by a Type-B MCB CPD o Table 41B1 in IEE, 2D in OSG 16th lists ---- 16A requires Zs < 3.00ohm ---- 10A requires Zs < 4.80ohm ---- 6A requires Zs < 8.00ohm o House socket will require a 10A or lower Type-B CPD ---- CPD disconnects Earth Fault within 0.4s & 5s with 10A MCB ---- irrespective of whether 2.5mm or 4.0mm cable used
I doubt the trip characteristic of a SFCU fuse protected spur off a 32A Type-B ring feeding an outside socket will do. It would require a dedicated circuit with 10A MCB fitted.
Earth Fault Current... o Iprospective-earth-fault = Uo / Zs ---- for 2.5mm flex = 230 / 4.36 = 53A ---- for 4.0mm flex = 230 / 3.02 = 76A o Type-B breaker instant trip characteristic requires 5*Ln ---- for a 10A Type-B CPD instant trip (0.1sec) = 50A ---- both 2.5mm flex & 4.0mm flex achieve this ---- disconnect time ( 50V has
Reply to
Dorothy Bradbury
But if you trim it back to the same point every year you'll only be cutting new growth which won't be that thick or hard.
Reply to
Extension cable sounds quite workable. An RCD would be needed, and significant care taken re thorns.
However I'd be asking whether the car access was on a level surface, and if so would be tempted to look at a bolt-on roofrack with a dexion-like structure added to it and the trimmer bolted to it. Make 1 pass in lowest position, move it up, make another pass, etc. Let the car do the work!
Reply to
Except you can't cut it back to the same point each year - it develops a huge knot at the cutting point, so you have to cut it very slightly longer each year, then after 10 years, cut it all back below the gnarled mess with loppers and start again.
(I have some 400 metres of hedging round my house, mostly hawthorn. After doing it myself for a couple of years, I now pay someone to cut it. It takes 2 (young, fit) blokes 2 days to do - it used to take me about 5 weekends.)
Reply to
Indeed. It takes me vest part of ahard day to heft a petrol trimmer to the inside of the hedge..the farmer does the top in 1/2 hr with flail..
Reply to
The Natural Philosopher

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