Electrical safety check please

[tony359]

Greetings,
A couple of years ago I bought a house with a double garage. The garage gets power from the garden socket (I was then told the garage used to be a car port, that's why it takes power from the socket). The garden socket comes from a dedicated breaker rated 16A and - from what I can see - runs on a 2.5mm line.

I have upgraded the electrical system in the garage myself, installed a DB with a few breakers, each running a different line. I have two for sockets, one for the motorised rollers, one for lights. I have recently installed a powerful heat pump to heat the place. It's rated 17.5A max (it's inverter so it only goes 17.5A when maxed out).
My questions are:
- in terms of house insurance, would it be wise to ask a qualified electrician to 'approve' the system in case (touch wood) anything happened?
- Would it be legal to replace the 16A breaker with a 20A breaker at the house DB - given that the cable running to the garage is a 2.5mm?
- The small DB I installed in the garage comes with 32A breakers for the sockets. The 16A breaker in the house would trip before that of course and I am fine with that but can I leave the 32A in place or is that against regulations?

Basically, I want to be safe and not have issues with the insurance in case of an accident.

Thanks
Tony

 

[JohnW2]

The garage gets power from the garden socket ... from a dedicated breaker rated 16A and - from what I can see - runs on a 2.5mm line. .... I have upgraded the electrical system in the garage myself, installed a DB with a few breakers, each running a different line. I have two for sockets, one for the motorised rollers, one for lights. I have recently installed a powerful heat pump to heat the place. It's rated 17.5A max (it's inverter so it only goes 17.5A when maxed out).

It sounds as if you have loads, or potential loads, appreciably in excess of what should be supplied by a 16A circuit.

Would it be legal to replace the 16A breaker with a 20A breaker at the house DB - given that the cable running to the garage is a 2.5mm?

That, per se, would probably be acceptable, but what sort of cable is this and where does it run?

The small DB I installed in the garage comes with 32A breakers for the sockets. The 16A breaker in the house would trip before that of course ...

By no means necessarily.

... but can I leave the 32A in place or is that against regulations?

Given the 16A one protecting the whole supply, that one is irrelevant/redundant, so it could be anything you wish (or removed entirely).

Is this circuit RCD protected?

It sounds as if you need an electrician to look at all this, not the least because I suspect that you will not have been able to test it properly.

Kind Regards, John

 

[tony359]

Circuit is RCD protected. It runs in the house to a fused switch on the wall and then goes outside, underground via an armoured cable, on to the garage wall into an outdoor socket. I wired the new DB from the socket (in parallel to the exiting cable). I used T&E, the house is 5y old, everything I can see existing is T&E besides the armoured cable running under the garden.

 

[JohnW2]

Circuit is RCD protected. It runs in the house to a fused switch on the wall and then goes outside, underground via an armoured cable, on to the garage wall into an outdoor socket....

Are you saying that the connection from the cable from the CU to the armoured cable goes through a Fused Connection Unit (FCU)? If so, the biggest fuse that could have in it would be 13A, which would further reduce the current available.

Do you know what size the armoured cable is? Is that also 2.5mm²?

What loads in addition to the heat pump do you envisage using from the sockets?

As I said before, I think you probably need the advice of an electrician, not only to inspect and test (and maybe comment upon) what you have done, but also to determine whether the supply is adequate for your requirements.

Kind Regards, John

 

[winston1]

Is the fused switch on the wall a FCU with a 13 amp fuse in it? The plug in the garden socket will have a 13 amp fuse as well. So you certainly don't need a DB and breakers in the garage. All the sockets can be connected directly. Use a switched FCU with a 5 amp fuse for the lights using the switch as a light switch. The motorised rollers can be via a FCU as well.
As for your heat pump that should not be connected as it will overload your max 13 amp circuit.
There is no point in upping the 16amp MCB to 20 amps as the whole circuit is limited to 13 amps by the plug in the garden socket.

 

[JohnW2]

Is the fused switch on the wall a FCU with a 13 amp fuse in it? The plug in the garden socket will have a 13 amp fuse as well....

I've just commented on the FCU (which the OP will probably have to get rid of, if he is to have any hope of getting enough power for his needs), but my reading was that the circuit is not going through a plug, but, rather has been wired ('from the back of') the existing socket ...

.... I wired the new DB from the socket (in parallel to the exiting cable). I used T&E

Kind Regards, John

 

[tony359]

John is correct, the garage DB is wired in parallel at the back of the socket.
Indeed the switch in the house is an FCU. So that has to be changed/removed, thanks.
The armoured cable is 2.5mm.

In terms of needs, it's my DIY room, I can live with some limitations when the heating is on. Again, keeping the Heat pump fan to low speed also reduces the compressor max power to 4-5 amps so that's not a big issue.

I installed the DB in the garage for additional safety and for flexibility - in case I want to isolate only one part of the circuit.

Assuming I remove the 13A FCU from the circuit, can I then replace the 16A breaker with a 20A one and have a safe and 'legal' 20A line to my garage? I will definitely look for an electrician to test/inspect anyway so feel free to comment!

Is there a limitation on how many splices a run can have - from regulations point of view? I use Wago connectors (the label says rated to 32A), I already have two splices before reaching the DB in the garage. If I remove the FCU that would add a third one.

Thanks for your help BTW!

 

[JohnW2]

John is correct, the garage DB is wired in parallel at the back of the socket. Indeed the switch in the house is an FCU. So that has to be changed/removed, thanks.

It could be replaced with a 20A double-pole switch, or merely a 'joint' (with a connector block, Wagos or whatever) behind a blank plate.

Assuming I remove the 13A FCU from the circuit, can I then replace the 16A breaker with a 20A one and have a safe and 'legal' 20A line to my garage? I will definitely look for an electrician to test/inspect anyway so feel free to comment!

That ought to be OK, but you ought to ask the electrician before you do it, to make sure that he/she is not going to have a problem when he/she 'inspects' it!

Is there a limitation on how many splices a run can have - from regulations point of view?

No - but any joints have to be 'accessible' unless they are 'maintenance-free'.

I use Wago connectors (the label says rated to 32A), I already have two splices before reaching the DB in the garage. If I remove the FCU that would add a third one.

No problem. If the joints were to be inaccessible, certain Wagos (in a Wagobox) seem to be acceptable (some debate ) as maintenance-free.

Kind Regards, John

 

[tony359]

Thanks.
All the joints are indeed accessible. I ran most of the wiring in the loft I created in the garage (for insulation purposes) and everything is very accessible and can be easily inspected. I totally understand the risk of joining two cables behind a wall!

Cool, it seems it's not so bad then. I will try and find a good electrician to inspect the new system. Thanks for your time so far!

 

[JohnW2]

Cool, it seems it's not so bad then. I will try and find a good electrician to inspect the new system. Thanks for your time so far!

You're welcome. As I said, I would suggest that, having found an appropriate electrician, you discuss what you plan to do with him/her before you actually do it - just to avoid any possible subsequent problems!

Kind Regards, John

 

[tony359]

I will definitely hold off any major changes to the system, thanks.

 

[ban-all-sheds]

I have upgraded the electrical system in the garage myself, installed a DB with a few breakers, each running a different line.

What made you think that you knew enough to do that?

What did you do about testing?

- Would it be legal to replace the 16A breaker with a 20A breaker at the house DB - given that the cable running to the garage is a 2.5mm?

Why do you suddenly care about that given that you have already broken the law?

Basically, I want to be safe and not have issues with the insurance in case of an accident.

Why didn't you think about that before?

 

[tony359]

Gosh I thought that my previous experience on this forum was just a one off.

What makes you think I'm not qualified to work on electricity?

Go and patronise someone else please.

Goodbye.

(Thanks again John for your assistance!)

 

[ban-all-sheds]

What makes you think I'm not qualified to work on electricity?

This:

I have upgraded the electrical system in the garage myself, installed a DB with a few breakers, each running a different line.

A CU on a 16A circuit.

I have recently installed a powerful heat pump to heat the place. It's rated 17.5A max (it's inverter so it only goes 17.5A when maxed out).

A 17.5A load, plus whatever else is on, on a 16A circuit.

The small DB I installed in the garage comes with 32A breakers for the sockets. The 16A breaker in the house would trip before that of course

No knowledge of discrimination.

So - what did you do about testing the garage installation before and after energising it? I mean - if you are qualified to have done the work you must know what should have been done, and done it, no?