New Light Trips The Electrics Off

[sienewman]

I have electrics in an outbuilding with a separate fusebox to the house. I have replaced the old bulb light with one of those florescent tube lights and wired it in, however every time I turn the new light on it flicks the electrics off. The plug sockets in the room are all working fine, it's just the light that trips the electrics off. Any advice on what is causing this and how to fix?

 

[ban-all-sheds]

What's tripping? An MCB or an RCD?

What wires were there at the old light, and how did you connect them to the new one?

 

[sienewman]

Please see the attached image. On the fusebox the first switch (on the bottom in the photo) is tripping off. I have attached a photo also of how I connected the wires.

100_4657

• sienewman
• 6 Nov 2015

100_4658

• sienewman
• 6 Nov 2015

 

[ban-all-sheds]

Why are there two of each colour?

Were they connected together like that in the old light (i.e. both reds together, both blues together and both yellows together)?

 

[sienewman]

That is how they were on the old light. I just put them in the new light exactly as they were previously. One of the sets of wires goes back to the fusebox, the other goes to the light switch.

 

[EFLImpudence]

Did it used to trip before?

 

[bernardgreen]

That is how they were on the old light. I just put them in the new light exactly as they were previously.

Are you sure, were not the two reds joined in one terminal and connected to nothing else.

One of the sets of wires goes back to the fusebox, the other goes to the light switch.

Then one set is power from the fuse and you have connected the switch across this supply. Switch on and there is a dead short across the mains. Hence the trip of the MCB

You need 4 terminals

The existing terminals
1/ one white and one blue
2/ earth
3/ the other white and the other blue

and the extra one
4/ the two reds

 

[ban-all-sheds]

That is how they were on the old light.

I think we can confidently say that that is not the case.

I just put them in the new light exactly as they were previously.

Nor that.

One of the sets of wires goes back to the fusebox, the other goes to the light switch.

And we can probably say that both of the blues are not neutrals, that one is a switched live, and that you have connected it to neutral, thus creating an almighty fault when the switch is closed.

Does the light come on, and stay on, with no drama from the circuit breaker when the switch is off?

Look at what wires go to the switch, and think about how likely it would be that one would be live and the other neutral.

 

[sienewman]

I understand this must be a fault on my part as it didn't trip before. I am really not used to electrics and thought changing the light would be a simple enough job, it seems I was wrong. How do I fix this?

The light currently doesn't switch on at all, just trips as soon as it's switched on.

 

[EFLImpudence]

You need 4 terminals

The existing terminals
1/ one white and one blue
2/ earth
3/ the other white and the other blue

and the extra one
4/ the two reds

 

[bernardgreen]

One assumes there is only one switch controlling this lamp.

You may find that the switch fails to work in the near future as repeated short circuits will have damaged its contacts.

 

[sienewman]

There is only three terminals though, where is the 4th terminal for the red wires? I really do appreciate everyones help with this, I am a beginner for sure!

 

[bernardgreen]

The forth terminal is still in the shop. You have to add one of your own.

 

[sienewman]

The forth terminal is still in the shop. You have to add one of your own.

Ooops, that would explain the confusion and why I couldn't find the fourth terminal that I was supposed to be putting the red wires in!

 

[stem]

Of course, none of this takes in to account the two yellow wires. It may be that they are simply not used and are taped up out of the way... On the other hand............ I would suggest you carefully check what exactly each of the wires is connected to at the other end.