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I'm in the UK and want to replace the connector on my lawn mower. I see you can buy products like this that state they can be used for garden equipment. However, the connector can be plugged in either way, so internally it could have one side with the live connected to the neutral and the other side with the neutral connected to the live?

From what I have read, this is not a problem. If it isn't a problem, then why aren't all plugs able to be plugged in either way?

enter image description here

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  • \$\begingroup\$ Is the lawn mower a Class 2 double insulated one? \$\endgroup\$ – winny Jan 10 '18 at 15:30
  • \$\begingroup\$ The manual mentions "Our products are double insulated to EN60335" but no mention of a Class \$\endgroup\$ – wforl Jan 10 '18 at 16:28
  • \$\begingroup\$ Same thing. Then no problem. You are safe. \$\endgroup\$ – winny Jan 10 '18 at 19:51
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From what I have read, this is not a problem. If it isn't a problem, then why aren't all plugs able to be plugged in either way?

What you have read is only partially accurate.

In reality, and in most cases, a simple appliance or equipment will normally work fine regardless of which way round the line and neutral is connected. Since the voltage is AC it sort of does not have a polarity like DC has positive and negative terminals.

The issue is the switching. Look at the two circuits below.

schematic

simulate this circuit – Schematic created using CircuitLab

The circuit of the left is wired the right way around. When the switch is off the lamp or motor or whatever is connected to neutral and, theoretically, is in a safe state and can be touched without electrocuting you. (Though I would not actually do that just in case the wiring is backwards in general.)

The circuit on the right, on the other hand, has everything live when the switch is open. This makes it a MUCH more dangerous appliance.

Note if the thing contains a fuse, the same issue occurs when the fuse blows. But now, if there happens to be a short to ground in the wiring, the fuse will not blow in the right circuit. Hopefully a ground fault interrupter will take care of that instead.

As such, a standard is employed to ensure the mains is normally connected the right way around.

In reality, in most cases, as long as you do not plan on taking the covers off and working on the guts with the power attached, and the device is a Class II type built correctly with the proper double insulation techniques, the connector orientation does not matter.

Ultimately though you should either use a keyed connector or a non-reversible three pin type and leave the ground pin disconnected.

enter image description here

ADDITION: When cleaning the blades though you should unplug it. Something you should do anyway, but thought I would re-emphasise it. BTW any readers with gas mowers also need to remember to disconnect the spark plug when cleaning the blades too.

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  • \$\begingroup\$ So in the case of a lawn mower connection it's completely safe? \$\endgroup\$ – wforl Jan 10 '18 at 15:05
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    \$\begingroup\$ @wforl Only if the lawnmower is a Class 2 appliance. \$\endgroup\$ – Jeroen3 Jan 10 '18 at 15:28
  • \$\begingroup\$ Remove the "completely". Nothing is completely safe, not even a 1.5V battery as a child may choke on it. Moreover you can only use that plug if your equipment is double isolated. I think all electric garden equipment is, but I am not sure. \$\endgroup\$ – Oldfart Jan 10 '18 at 15:30
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    \$\begingroup\$ There are control circuits that switch the neutral line - washing machine controllers etc but they are enclosed so "safer"... until someone takes the cover off... \$\endgroup\$ – Solar Mike Jan 10 '18 at 15:34
  • \$\begingroup\$ @Jeroen3 yup, thanks for the reference, I added that to the answer. \$\endgroup\$ – Trevor_G Jan 10 '18 at 15:43

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