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Help with table saw switch and cable

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Westwood

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I am refurbishing an 18 year old SIP ten inch saw and need to upgrade the on off switch to something like the photo attached, and I have to extend the power cable. So I'd like to buy new cable and rewire fully. i have a new 16 amp circuit to connect that to. There seem to be hundreds of switch options out there, many American clearly.

Can any kind person point me in the direction of a switch suitable for british 240v electrics I can purchase and help with the right grade of cable please ? Thanks in advance
 

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sunnybob

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I just LUUURVE that 13 amp plug :shock:
Whoever wired that, DO NOT let them fit the new lead and plug.
If it was you, dont admit it on a public forum (hammer) (hammer) :roll: :lol:
If its a single phase motor, that giant switch box wont be required. A pic of the plate on the motor will answer that question.
Axminster and ebay among others are filled with NVR switches.
 

Westwood

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I hasten to add that NO, I didn't wire that plug ! That is as I bought the saw.
Hence my plan to rewire it completely with new and better cable running from a new NVR switch to a properly wired 16 amp male socket.
Yes I know that eBay has loads of switches out there - the problem is choosing something suitable. Was kinda hoping that someone here with a similar saw or the experience could suggest one or two suitable switches. I'm more than happy with an eBay purchase , just haven't bought such a switch before and don't want to but some piece of rubbish.
Better pics of both the existing MK switch and the makers' plate following
 

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Trevanion

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Have a look at the actual motor plate and see what the amp rating is, then buy a suitable 240v DOL starter like this in the amp range:
https://www.ebay.co.uk/itm/Dol-starter-1-phase-230v-or-3-phase-400volt-coil-Electric-motor-overload-fitted

You'll also need to pick up a couple of M20 cable glands to put on the box as the ones that come with it are a bit rubbish:
https://www.ebay.co.uk/itm/2-X-20MM-M20-NYLON-CABLE-GLAND-GLANDS-COMPRESSION-FIT-IP68-RATED-BLACK

I like to use SY cable, mainly because it looks good:
https://www.ebay.co.uk/itm/SY-Cable-3-Core-2-5mm-Steel-Braided-Multicore-Control-Flexible-Various-Lengths

Wiring the switch is pretty straightforward

Power cable in:
Live to L1
Neutral to L3
Earth to earthing plate

Motor cable in:
Live to T2
Neutral to T3
Earth to earthing plate

Bypass L2 to T1 with an extra length of wire, adjust overload to the amperage stated on the motor plate and put back together and the machine should start.
 

sunnybob

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From that description plate 3HP is roughly 21 amps. A normal NVR switch as you show is rated at 16 amps. :roll:
So unless the motor plate says different, youre going to need a switch as described above.
The motor plate is the decider because it could already have a different motor, especially if it was actually working on that 13 amp plug! :shock: :shock:
Have you looked inside? There might well be an iron nail across the live terminals. That would fit in with the wiring standard. 8)
 

Distinterior

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sunnybob":lpzbuyo0 said:
From that description plate 3HP is roughly 21 amps. A normal NVR switch as you show is rated at 16 amps. 8)
Would you care to elaborate on that observation please SB...?

By my reckoning,... 3HP is about 2250W which means it will draw a bit less than 10A under normal conditions....???
 

sunnybob

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according to t'internet..... 1HP at 240 volts is roughly equal to 7 amps.
I used my non tehnical brain to multiply that by three.
I cant claim to have electrical theory in my mind, so I always use the resources available.
If that is wrong, I can find the bit I read and pass it on to you.
 

Distinterior

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1 HP = Approx 750 Watts x 3 = 2250 Watts
2250 Watts ÷ 230 Volts = 9.782 Amps

I t may be possible that the information you looked up was for a 110/120 Volt motor...?
 

Westwood

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You're losing me guys !!!!
I thought this was a case of choosing a new NVR switch and wiring that to my new 16 amp set up
I'm happy with the SY cable and will go for that thank you, Trevannion.
I'll have a look inside and see if I can post up other pics
 

sunnybob

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Forget the theory!
You still havent told us what the rating is on the motor plate.
Without that info, you risk (worst case) setting fire to something.
 

sunnybob

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Distinterior":36whwmo0 said:
1 HP = Approx 750 Watts x 3 = 2250 Watts
2250 Watts ÷ 230 Volts = 9.782 Amps

I t may be possible that the information you looked up was for a 110/120 Volt motor...?
on this site
https://www.engineeringtoolbox.com/elct ... _1499.html

it gives this
230 volts motor - single-phase : 7 amps/hp

I dont have the theory to make ANY argument, but this is where I got the info from.
 

Trevanion

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I've got a 2.2KW/3HP motor that's rated at 11.6A on the plate, and then I've got a 1.5KW/2HP motor that's rated at 14A on the plate, and another 1.5KW/2HP rated at 7A on the plate! :-k

I know absolutely zilch about motors so I have absolutely nothing to add more than that.
 

Westwood

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Opened up but can't see any other motor plate inside Bob.
Surely the plate would be in a visible spot on the outside of the saw case rather than deep within ?
Any SIP owners verify that please ?
Pic of the back of the switch there too.
And yes, I can see it needs a thorough clean and TLC.
I've had it running with the 13 amp plug that it came with but want to make a proper and safe job now
 

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Trevanion

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The plate will be on the motor itself, you may need to wangle your phone in there to take a photo if it's not easy to see without taking the motor out.

You may need some new belts before long too, those look a little perished.
 
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