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Plumberpro, Plumber
Category: Home Improvement
Satisfied Customers: 40
Experience:  Fully qualified plumbing , heating and gas engineer 20 years experience
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I have fitted 4 x 20w LED lamps and 2 x 60w lamps outside via

Customer Question

I have fitted 4 x 20w LED lamps and 2 x 60w lamps outside via a dawn dusk sensor through a 3 amp fuse box to the garage & boiler circuit. When the boiler kicks in and lights are on it trips the switch in the consumer box but the 3 amp fuse is ok.
Why is this an how can I get the lights to stay on without tripping the circuit ?
Submitted: 4 years ago.
Category: Home Improvement
Expert:  AssuredElectrical replied 4 years ago.
Welcome, my name is XXXXX XXXXX I would be glad to assist you.
Let me get some additional information if possible.

1. The 4x20 and 2x60 lamps were an addition, all new, is that correct?

2. The switch that is tripping in the consumer unit, can you read a size on the switch?

3. Can the new lights be separated or do they all have to be together "ON" at the same time right now?
In other words, can we separate them for testing purposes?

4. Do you know everything that is on that same switch besides these lights and the boiler?

Expert:  dianne-cssm replied 4 years ago.
We received your customer service inquiry, however, we are unable to respond to you because we do not have your email address. Please contact customer support at [email protected] co. uk and provide us with your email address and a link to this question page so that we can help you. ( Thank you, XXXXX XXXXX Customer Support Team.
Customer: replied 4 years ago.


The answer to your questions are as follows.

1. All lamps are new.

2. There is no size on the actual switch as it controls a bank of 5 MCB

The MCB's control the following.

a. Lights downstairs & garage.

b. Ring, Kitchen & Living.

c. Ring Bedrooms

d. Ring, Garage & Heating

e. Hob

3. The lamps have all been tested independently.

4. As listed above.



Expert:  AssuredElectrical replied 4 years ago.

I do apologize for the delay in getting back with you. It seems your response did not notify nor post to my message board, so I was unaware of you providing the information.

I see that customer service has that part cleared up now by their post to you.

On the lights, it sounds as though when the tripping occurs, it happens to the main one that controls those 5 MCB's?
Is that correct?

Which one of the MCB;s listed has these lights connected?

Unsure of why the switch has no number, if it trips it should have a specific number it is rated for to operate.

Possibly a picture of the consumer unit with that switch could be posted?

Posting a picture is easy once it is on your PC, just CLICK HERE and upload it, then the site will give you links for the picture. Post the link here and then it can be accessed.

Thanks, XXXXX XXXXX I apologize for the delay in your response earlier getting back to me.

Customer: replied 4 years ago.

Hi, thanks for the response.

Yes customer service has cleared their query, thank you.


Yes, the lights trip the main RCD that control 5 MCB's.

The MCB's have the following listings.

1. Lights downstairs & garage.

2. Ring, Kitchen & Living room.

3. Ring & Beds.

4. Ring Garage & Heating

5 Hob

I have wired the lights from the back of a socket in the garage.

I am unable to send a picture to you at the moment as the work is at my daughters house and I cannot get access until later today.

I will take a picture then and send it to you, so no rush.

Many thanks for your response to date.

Expert:  AssuredElectrical replied 4 years ago.

Ok, thanks for the extra information, and when you are able, a picture may help as well.

It is interesting that the lights being connected to the garage and that is also on the same MCB as the heating, but they do not trip the MCB but the main RCD.

So, is it possible for you to do a test? It tales some extra time, but it does help narrow down the possibilites.

Since it is tripping the RCD, it leads me to believe that it is an earth leakage of some type.

Not knowing exactly how they are wired from the beginning to the end.
If you could disconnect the 2- 60 watt fixtures. Then see if the remaing 4 lights still trip the RCD with the boiler running?

If not, it will have narrowed down the issue to one of those lights.

If it still trips, can you reconnect the 2- 60 watts and disconnect the 4-20 watts for the same test.

I think this gives you an idea of the reasoning on the tests, to eliminate what may work on the line and what does not.

If it is an earth leakage situation, then maybe we can narrow it all the way down to the one light that may be causing the issue.