Which fuse for Meddings M10 Drill

Hello folks,

I own a Meddings M10 High Speed Bench Drill. I use this for drilling very small holes (0.5mm - 1.5mm) in wood, it really works very well for this - I love it. I bought it second hand a few years ago, I believe it is from the 1970s.

Yesterday I was drilling with it, and it stopped working. Fortunately it was just the Fuse that had gone. However, it had a 5 Amp fuse in it. Please excuse my ignorance here - but is there any reason for this? Pretty much all of my other machinery (Bandsaw, etc.) all use 13 Amp fuses in the plugs.

I wonder if there is a reason it might have had a 5 Amp fuse, or whether somebody just put the wrong fuse in before, and it should infact have a 13 Amp fuse in it...

I'd really appreciate any advice here!

Thank you,

Theo

Theo,

1/4hp, 5A will be fine.

Fuses die from old age as well.

Welcome to the forum Theo.

I agree with Francis. The motor is probably between 0.5 and 1HP, and 1HP is about 3A in. A 5A fuse is reasonable.

The failure may be normal. Motors start with a heavy surge current, which causes fuses to age somewhat prematurely. Takes years, and fuses are easily replaced.

However, if it blows a second 5A fuse in short order likely something is wrong, so feel free to ask how to fault find it.

Dave

The above comments on blowing a 5A fuse a second time are correct and good advice, as is the comment that fuses die of old age. Lower current fuses have thinner elements and thus are more fragile.

However it should be noted that the fuse rating does not depend on the drill (or other load), it depends on the size of the cable connected to the plug. A fuse in a UK plug is there to prevent the flexible cord from overheating due to overload or fault. Any protection provided to the load (motor in this case) is co-incidental. That said it is good practice to use a fuse rated closer to the expected load current. A 5A fuse is good for about a kilowatt or > 1HP.

Robert G8RPI.

The fuse is there to protect the supply lead, not the machine motor.

Completely agree with last two comments: the fuse in a plug protects the cable from the plug to the device, and therefore should be rated for the cable.

A standard UK 13A plug refers to the maximum current it can safely pass, but unless the cable used is also 13A rated, the fuse in the plug should be changed to a lower rating.

If the fuse rating is too high for the cable used, a fault in a device causing it to draw too much current could melt the cable, with very dangerous consequences.

Very few domestic devices draw 13A; kitchen double ovens come close but that's about all.

Edited By John Doe 2 on 06/07/2022 10:14:00

The 13A system might have been fine in the 50s when it came out, but The square pins and fuse holder were points of higher reistance and the fuse it's self would often run hot. Poor quality plugs have been I suspect the cause of house fires,I would question whether an ordinary 13A plug CAN carry 13A for any length of time without heating up ! Just look at the socket used for a washing machine or tumble drier, or anything drawing 2.5 or 3 Kw, the right hand pin hole will be brown - I rest my case !

A fuse is no way to protect an electric motor, though better than nothing, A proper direct on line starter incorperating a no volt release is the proper way, but these are not cheap.

Back to the question, replace with a 5A fuse, if that then fails you have a problem. Check that there isn't an unwanted load, bearings tight may be. Noel.

Many years ago at college we carried out a 13 amp load test on 13 socket outlets, together with the plug which goes into the outlet. All were British made, those brass plated steel pin ones plugs from the far East weren't available those days. When loaded to 13 amps it was only a short time before both the plug and socket outlet got hot to touch and arcing soon took place. When we took the socket outlet to pieces the so called copper connections were softened and had little or no tension left, the plug was OK but hot. The old 10 and 15 amp round pins ones were much better, but were not deemed to be unsuitable for a ring main circuit, back in1947. All the modern industrial plugs and sockets are round pins. Today many 13 amp plugs are steel pins brass plated, and when the brass is worn away the plug over heats Put a magnet near your new 13amp plug. Yes, in the trade it's well know that fuses age and fail, just like us. John

Plenty of devices draw close to 13A The classic is the kettle 3kW = 13A.
Quality 13A sockets don't overheat unless worn out. A 13A plug with brass plated steel pins is a fake.

A direct on line starter does not provide overload protection by default, it's an option.

Ronert G8RPI

The only sockets I have found running warm had a loose screw on the connector.

Wasn't the old round pin system based on spurs??

Most of the old round pin sockets I remember had split receptors with spring steel closer putting pressure onto the pin of the plug inserted, the pins also had a slot for a part of the pin length, these design features provided better contact than modern 13A plugs offer.

Yes to spurs for 5A and 15A 3 pin round sockets.

Emgee

Where do your plugs come from John? I've just tested 59 of mine, a mix of new and old, and none of them have magnetic pins!

The report of 13A sockets overloading is surprising. The covers of 13A plugs can get warm enough to discolour the plastic because a fuse running at maximum is a miniature electric fire contained inside a ceramic tube, but even hard pushed sockets run cool unless damage causes arcing.

Several posts have suggested fuses are fitted to protect the cable. 'Not wrong' as they say, but fuses are fitted to prevent excessive current being drawn for too long. They protect the whole system. I wouldn't fit a 13A fuse to a 1A radio even if the cable was man enough to take 13A without melting the insulation. If the radio catches fire, I've got a problem.

Fuses age because they get hot when run close to the limit, but they can take a lot more current than the rated value before blowing. A 13A fuse will take 20A almost permanently and 30A for about 5 minutes before giving way. Circuit breakers trip out closer to the rated current, but become unreliable after being popped several times, and mean-bean owners don't replace them. An advantages of fuses is they have to be changed. Except of course, bodgers are tempted by paper-clips and old nails!.

Dave

Except of course, bodgers are tempted by paper-clips and old nails!.

Then there are the Darwin award contenders. Not a mains circuit, but a vehicle. Fuse was replaced with a 0.22 live bullet. Not sure if the fellow was just removed from the breeding stock or removed permanently.

Most NVR switches that I encounter in cheap drills, sanders, etc. have no overload protection. They are simply latching switches that go off when the power source is interrupted. Good quality DOL starters incorporate a thermal overload (settable to the full load current) and latching relay. But as you rightly say they are not particularly cheap.

An affordable improvement on the NVR only option is to add a thermal circuit breaker. I have previously encountered one of these on a fairly expensive router / trimmer.

thermal circuit breakers (RS components)

Continuing from my post above (suggesting a resettable fuse could be considered), here is an example showing trip characteristics from a randomly sampled datasheet: