Garage lights trip RCD

[Cameron_s92]

Looking for a bit of guidance, we recently installed a garage consumer unit to replace the "twin and earth running up the driveway" job the previous owner left. We used 16mm SWA to future proof for EV charging. The T&E cable was running off a socket in the hallway and powering 3 LED battens and a socket with no issues.

I decided to move the garage over to its own MCB. When you power the LEDs without lamps in everything is fine, when you power the LEDs with just 1 lamp in a unit, the man RCD trips in the house. The RCD was already tripping at random times over winter but we though this was due to the rain getting into the garage. Everything (including the garage roof) has since been replaced. I've double checked all the polarity and that seems fine, the LEDs are plastic so no earth point, the only other thing I can think of is an inrush current.

Would love to hear any feedback or souloutions the group has

 

[pete01]

Neutral in wrong bar in house DB assuming twin rcd?

 

[ericmark]

I would also go for wrong neutral first.

 

[Murdochcat]

inrush current won't trip a RCD and if the "new" garage MCB is on a shared RCD you can't use it for an EV

 

[Cameron_s92]

inrush current won't trip a RCD and if the "new" garage MCB is on a shared RCD you can't use it for an EV

That's good to know, the EV is a long term plan, but didn't want to spend twice in 5 years.

 

[Murdochcat]

That's good to know, the EV is a long term plan, but didn't want to spend twice in 5 years.

Hum

Photo of main CU and garage CU?

 

[Cameron_s92]

Yeah, rechecked the photos and I think i have followed the wrong neutral tail from the RCD so its on the wrong bar as you all pointed out.

The other side of the main CU only has a 2 pole switch, and no RCD. If I moved the garage to that side, is there anything extra i would have to do to satisfy UK regs? Presuming an RCD in the garage CU would be a minimum.

 

[Murdochcat]

Photos

 

[ericmark]

As said EV charging rules are charging week by week, the only way to future-proof is to put in a duct, so required cable can be used. I personally decided that RCD's in the main cause too much trouble, so went for mainly RCBO's except for two RCD sockets which fed my freezers.

In the main for an EV it needs some way to measure what the house is using, and needs some way to give the supplier control, so it can use cheap off-peak supplies, and not overload the system, so the supply cable often has data cables within it.

Both solar panels and EV charging points need permission and/or registering, so any work involving them needs to be done by electricians who can complete the required forms, so even as an electrician with 50+ years of experience, I could not fit my own EV or solar panels.

Even fitting a supply to a garage, I should pay £100 plus vat to register the work. And clearly if expecting another electrician to add to what I have done, the paperwork must be in place, this varies depending on where you live.

With SWA cable, I would not be fitting an RCD at the origin, and I would be considering if a TN-C-S or TT supply to shed was most appropriate, considering the supplies may be used outside. Also, materials of which the outbuilding is made from, if metal, then likely will need a TT or TN-S supply, and TN-C-S can't be used.

The main problem is Loss of PEN it seems this is becoming more of a problem, back in 2005 when this guidance was published about supplies to out-buildings the problem of broken PEN was rare, and little is said about TT supplies.

The main problem for the DIY is testing, without the test equipment it is trust to the Lord, and I suggest when doing electrical work, that you download the free forms from the IET website and complete them, not so much as they are needed, although they are, but as a check sheet to ensure you don't miss out any tests.

 

[Cameron_s92]

Here is the house CU, I believe that is a TN-S. This is before I started, the spare 32A MCB on the non RCD side is now on the RCD side and is being used for the garage

 

[endecotp]

Here is the house CU,

There seem to be only 3 power conductors going to the meter. What’s going on?

Edited to add:

It looks like the neutral current doesn’t pass through the meter. I guess it disappears under the board and into the back of the CU. Did you do that? I guess the meter will still record correctly, if it measures only the live current and the live-neutral voltage. Beware that having what should be a pair of conductors entering a metal CU through different holes can have dangerous consequences due to eddy currents.

Or have I misunderstood what is visible in the photo?

 

[pete01]

Wheres the new swa cable?