Fuse for garden office keeps tripping

Crazy_Diamond

Hello,
I recently had electrics for a new garden office installed. A new consumer unit was installed in the original house plus a consumer unit in the garden office. I was told this would provide me with sufficient power to run a heater, office equipment, lighting and also supply 32a for a hot tub if we were to install one in the future.

I am finding that the fuse for the garden room in the consumer unit in the house keeps tripping when I run a 3kw heater plus my computer bits which add to a further 200w so about 15a max. Any ideas why this might be? When I spoke to the electrician that installed it he said that because the consumer unit was rated at 40a it could overload and suggested uprating it. However my 15a is way under this, could anything else be causing it to trip? I have tested all the appliances and they are fine - it trips with 2 different heaters. Would water cause this problem? The room is a little damp at present but the tripping does seem to occur when the appliances have been on for about 30 minutes.

Any advice would be much appreciated, I am sitting in 8 degrees cold at present as I am too scared to put my heater on!

Crazy_Diamond

Also does anyone know why it would be the fuse in the main house that would trip rather than the one in the consumer unit in the garden room?

muckybutt

Terminology is the key here as are photos.

The house fuse is it a fuse - circuit breaker or an rcd ?

Your house electrics are they covered by an rcd ?

From what you have said so far it sounds to me that the cable to the garden room is protected by an rcd rated at 40A. Then inside your garden room there is another consumer unit that is not rcd protected, this is key in knowing what it what.

What I suspect is the heaters are tripping the new board in the house as that is far more sensitive than just a normal fuse / mcb. Your house electrics I am presuming that they are not covered by an rcd therefore when you plug the heaters in the house they wont trip.

Util you post photos or a description of all the fuses / breakers etc then we're just clutching at straws

Crazy_Diamond

Many thanks for your reply. I will try to post photos later but I can tell you that the consumer unit in the garden room states on it:

'this installation or part of it is protected by a device that automatically switches off the supply if a fault occurs'.

It has a rating of 80a.

muckybutt

That's a start then as you have an RCD somewhere !

Crazy_Diamond

This is the one in the garden room
http://www.tlc-direct.co.uk/Products/CPD02P.html

muckybutt

Providing that's the one you certainly have in the garden, then the unit in the house is where the RCD is which is what will be tripping out as you have said.

It could be a couple of things :

Faulty heaters or the cable supplying the garden room has a fault on it.
Given that everything else in the garden room works and does not trip the circuit then I am swaying more to the heaters being faulty.

When the electrics were put in did the electrician give you any paperwork to say the supply had been tested ?

Owain_Moneysaver

If it's that one you don't have an RCD in the garden room as that unit is main switch only.

Could you post a photo of the house consumer unit and show what actually trips, and also a photo of the Electrical Installation certificate for the garden room.

Crazy_Diamond

Here is a photo of the main consumer unit in the utility. The unit on the right is the new one installed specifically for the garden room although it does also have our kitchen lights on it.

Crazy_Diamond

The switch that trips is the black one in the middle of the box on the right labelled summer house.

Crazy_Diamond

muckybutt wrote: »

Providing that's the one you certainly have in the garden, then the unit in the house is where the RCD is which is what will be tripping out as you have said.

It could be a couple of things :

Faulty heaters or the cable supplying the garden room has a fault on it.
Given that everything else in the garden room works and does not trip the circuit then I am swaying more to the heaters being faulty.

When the electrics were put in did the electrician give you any paperwork to say the supply had been tested ?

I don't think it is the heaters. I have tested several including one which is brand new and they all seem to trip it. The tripping is very ad hoc and is normally 30 minutes or so after the heater has been turned on. It seems to be tripping more frequently as time progresses.

I do have the paperwork, is there anything specific that would be useful to post. I am a bit reluctant to upload it all as it has personal details.