The quickest way to do it in terms of the time is a splash of pva (be sensible regarding the electricity supply). Bonding, which is a plasterers undercoat that can be applied thick then multi finish or normal filler. Problem with this is bonding and multi finish usually only come in big sacks and you only need a cup full. If you are feeling brave then ask at a building site for some bonding.
You can do it in 2 or 3 goes with a decent filler like tx110 from toupret, that's a product worth having in a cupboard anyway. Read the instructions fully and mix it according to the packet.
It's also quite popular to remove the light switch from the back box and put a plastic bag over it with tape or a rubber band around. Just make sure you don't accidentally touch any contacts with the trowel or filler knife if you do it that way.
Bit late to this but I hope it's worked out well. You can vary the drying time of the TX110 by changing the temperature of the water you mix it with. I've become very scientific about the amount of powder to water as well because it is so good a filler when it's the right consistency.
The quickest way to do it in terms of the time is a splash of pva (be sensible regarding the electricity supply). Bonding, which is a plasterers undercoat that can be applied thick then multi finish or normal filler. Problem with this is bonding and multi finish usually only come in big sacks and you only need a cup full. If you are feeling brave then ask at a building site for some bonding.
You can do it in 2 or 3 goes with a decent filler like tx110 from toupret, that's a product worth having in a cupboard anyway. Read the instructions fully and mix it according to the packet.
It's also quite popular to remove the light switch from the back box and put a plastic bag over it with tape or a rubber band around. Just make sure you don't accidentally touch any contacts with the trowel or filler knife if you do it that way.