Mini MCB tripping when using lawnmower? help please

[Spoonyboy]

Hi, I've just moved to a new house (10 years old) and all the electrics look standard by the builder, apart from some downlights in the house.

The problem I have is using the lawnmower or hoover from the plug in the garage trips the MCB, it is fine when using a corded drill though. The lawnmower works fine if plugged into the house sockets.

This is the setup I have.

Main consumer unit in house with a trip switch to garage (120EB6 B20) 20amp i think?

This goes to another smaller consumer unit in the garage with an RCD 100A and 2 mcb's.
MCB1= The sockets which is 606B B6 (6 amp?)
MCB2 = The light which is 616B B16 (16 amp?)

I'm thinking 6amp is too low for the double socket/lawnmower? (I was also going to spur off the double socket for an outside light).

I have checked over the wiring and none of it looks loose. Any help would be really appreciated. I have pictures of inside the garage consumer unit if that is any help.

 

[Steve]

Lights should be on 6 amp. Sockets on 16 amp.

 

[Spoonyboy]

Lights should be on 6 amp. Sockets on 16 amp.

Thanks, I will double check the wiring again, make sure they are the correct way around. Cheers for the quick reply.

 

[Spoonyboy]

I traced the wires back to the consumer unit and they were wired into the wrong fuses as suggested. I swopped them over and everything works fine now. Cheers Steve!

I have another question now though. I want to wire two outside security lights, I have done this before and run a switched spur from a plug socket (only 1 light).

Because i need 2 lights and only have 1 plug socket in the garage I'm not sure that would be alright. Would it be better if I wired both direct into the garage consumer unit? (there is 1 blank MCB space)

If so what amp MCB do i need? (2x150w PIR lights) and is it ok to wire both to the same MCB?.

Greatly appreciate any help here.....I am done with electrics after this! hurray!

 

[Steve]

Another satisfied customer!

Press the button! (thanks)

 

[sparkwright]

I traced the wires back to the consumer unit and they were wired into the wrong fuses as suggested. I swopped them over and everything works fine now. Cheers Steve!

I have another question now though. I want to wire two outside security lights, I have done this before and run a switched spur from a plug socket (only 1 light).

Because i need 2 lights and only have 1 plug socket in the garage I'm not sure that would be alright. Would it be better if I wired both direct into the garage consumer unit? (there is 1 blank MCB space)

If so what amp MCB do i need? (2x150w PIR lights) and is it ok to wire both to the same MCB?.

Greatly appreciate any help here.....I am done with electrics after this! hurray!

You could wire into the spare fuse way of the garage cu, with 6 amp mcb.

Or you may be able to spur off the socket circuit at the cu, assuming your installation would allow this. In this case you would use the same size cable as the sockets to feed a switched fused spur, then use 1.0 or 1.5 mm thereafter.

Or possibly you could run another cable from the load side of the existing switched spur.

I imagine some or all of lights can be on the same switch.

 

[bongos]

Or possibly from the exisiting lighting circuit/MCB on to new switches/fittings.

 

[Spoonyboy]

Cheers guys.

Due to where the lights are situated its easier and neater to wire them direct to the garage cu. I will put a new 6amp mcb in to run them

 

[sparkwright]

Consider using a 16 or 20 amp mcb, 2.5 mm cable and a switched fused spur. This would give you scope to add an extra socket, if you should need one.

 

[Spoonyboy]

Consider using a 16 or 20 amp mcb, 2.5 mm cable and a switched fused spur. This would give you scope to add an extra socket, if you should need one.

Good thinking, i've got the 2.5mm cable and switched fused spur already.

My security lights are actually 300w not 150w. So I use a new 16amp mcb from cu to switched fused spur with 6amp fuse in, then off to the 2 lights from there?

Cheers!

 

[sparkwright]

Consider using a 16 or 20 amp mcb, 2.5 mm cable and a switched fused spur. This would give you scope to add an extra socket, if you should need one.

Good thinking, i've got the 2.5mm cable and switched fused spur already.

My security lights are actually 300w not 150w. So I use a new 16amp mcb from cu to switched fused spur with 6amp fuse in, then off to the 2 lights from there?

Cheers!

Yes.
The fuse in the switched fused spur would actually be 5 amp.
The wiring from the switched fused spur to the lights can be 1.0 or 1.5 mm cable.
Consider running separate cables to each light from the fused spur; rather than going from one light to the other light.
It will be easier to connect the lights, and you will possibly get a more weatherproof cable entry.
It also makes re-positioning a light in the future much easier.

 

[Spoonyboy]

Excellent! That all makes sense now and its actually easier to run two seperate wires from switched spur to the lights. The extra socket will really come in handy as well, great idea.

Thanks very much for the help.