Socket Tester Works Load Trips...

[NewHomeowner]

Hello everyone - I hope someone can advise me.

First up, I'm an enthusiastic DIYer, but I know my limits - What I describe below is a job for an experienced electrician, but I want to know whether there's something basic I'm missing before I call one out as they can be expensive and cash is tight.

I've just moved into a new (ish) house with a garage.  The garage seems to have power to it supplied by a Steel Wired Armoured cable - 3 cores red, blue, yellow. The Wilex consumer unit in the garage has a 20a circuit breaker and a 6a circuit breaker. The RCD is 63a.  All of these were empty (no wiring).  As an experiment, I wired up the 20a circuit breaker to a double socket to see if there was power. The Socket Tester showed three lights, so all good! - The garage would soon be a 'workshop'!

But .... as soon as I plugged in a lamp with a plug to get some light in there, the RCD trips. Same thing with a drill.  Just plugging IN the device tripped the RCD - Anyway, So....  I wired up a basic pendant light / switch to the 6A circuit breaker and the same thing happened definitely even before I turned on the switch - The RCD tripped. So, ANY power at all causes the RCD to trip but the socket tester did not.......cause the trip?

In the house, the circuit breaker labelled 'garage' is a 32A Crabtree startbreaker Consumer unit.  This did not trip, nor did the house RCD. 

Is the problem likely to be with the SWA cable? Or is the problem that the RCD in the Garage is higher than the circuit breaker in the house? (63 v 32)?

Thanks all - sorry for the basic question.

NewHomeOwner

 

[pewter]

Have you connected into the garage consumer unit correctly?

Is the garage RCD working correctly? It might need testing

 

[ProDave]

It sounds like your neutral is not through the RCD or something like that.

Can you post a picture of what you have done?

 

[Doc Hudson]

Welcome to the forum newhomowner. First of all reading your post it looks like you don't fully understand the difference between RCD's and MCB's (Miniature Circuit Breaker). A little explanation may help you get your head around what is happening. The MCB's (your 32A, 20A & 6A devices) detect overload: Too much power going down a cable to prevent overload and damage to the cables. Whereas RCD's detect very small amounts of current flowing to earth to prevent electric shock. The plug in tester will not trip an RCD, but anything that consumes more than 30miliamps can cause the RCD to trip if the wiring is wrong, or damaged.

Doc H.

 

[SPECIAL LOCATION]

Hello everyone - I hope someone can advise me.

I've just moved into a new (ish) house with a garage.  The garage seems to have power to it supplied by a Steel Wired Armoured cable - 3 cores red, blue, yellow. The Wilex consumer unit in the garage has a 20a circuit breaker and a 6a circuit breaker. The RCD is 63a.  All of these were empty (no wiring). 

Obviously there has been power there in the past.....

WHY did the previous owner disconnect it????

Is the RCD damaged / faulty ??

May need to get the RCD tested first to verify it is working correctly...

Guinness

 

[ProDave]

Obviously there has been power there in the past.....

WHY did the previous owner disconnect it????

My guess is a phart pee thing.

I'll bet the buyers solicitor asked about DIY electrics and part P certificates, so the seller just disconnected it and said there are no DIY electrics.

Nice to see the system is "working"

 

[SLIPSHOD & SLAPDASH]

Reversed polarity

 

[NewHomeowner]

It sounds like your neutral is not through the RCD or something like that.

Can you post a picture of what you have done?

I will post a picture up, but to date, other than connecting the temporary socket as a 'test' I haven't done anything.  That is to the Garage CCU.  MCB's and RCD were there, but no wiring out from the CCU, just the SWA IN to the CCU

 

[batty]

You say its a newish house I assume its probably at least 8 years old as the SWA is old colours. Is it an estate house? did builder not provide electrics in garage? more info is needed. I will say electric is dangerous if you don't know what you are doing to me it sounds like you are in this category. Welcome to the forum.

 

[kerching]

Just a thought....where did you connect the neutral in the garage board for your temporary test socket?

 

[Andy™]

You say its a newish house I assume its probably at least 8 years old as the SWA is old colours.

not always....

found a socket wired in 2c rubber flex w/o earth the other day. house wasnt built until mid 80's...

 

[batty]

Nothing ever surprises me see all sorts doing one at the moment  rewired but earth's are all cut off. Lucky I am doing it on day work and new owner wants it safe.

 

[sparkytim]

Nuetral / Earth reversal would explain it, check which colours are which at supply end and see if the same at the Garage Consumer Unit.

 

[NewHomeowner]

Thanks to everyone for their replies. I'm back home on Tuesday after a short break away at the in-laws.  Just to be clear - By NewHomeOwner, I meant I'm new at owning a home, NOT that the home is new.  I'd say it was 1950's, perhaps - probably explains the wiring colours - all the sockets are IN the skirting boards, for example!

I don't know if the previous owners ever had power in the garage.  They themselves only had the house for a couple of years, so it may not have been them that had it installed.

Kerching ...  the garage CCU has the RCD, and two CB's.  The RCD was connected red into right hand top of the rcd (the supply?), the yellow into the earth bar, the blue into the neutral bar. All of this was already done.

The only connection I made was my temporary socket into the 20A CB.  blue into the neutral bar, brown into the top of the circuit breaker, I sleeved the earth wire green/yellow and connected this into the earth bar.  I wired up the temp pendant in the same way.  Both loads tripped the RCD.

 

[steptoe]

ah, but how is the SWA connected at the main CU in the house?

also, to say LINE[red] in RHS of RCD means nothing, many [most I work with] RCDs have LINE[red] in LHS

 

[ProDave]

I think we really need that picture of the wiring in your CU when you are able.

 

[steptoe]

AH,

just noticed,

your neutral doesnt even connect to the RCD,

that is your problem,,,,,,,

 

[Barx]

well as others have hinted at. I would say the connections are wrong somewhere. Check in the main house CU see of the colours are connected same as in the garage cu. Then post a pic of inside the garage Cu, showing all the connections. You say the blue goes to neutral bar. Does that mean it doesn't through RCD first?

 

[Andy™]

Thanks to everyone for their replies. I'm back home on Tuesday after a short break away at the in-laws.  Just to be clear - By NewHomeOwner, I meant I'm new at owning a home, NOT that the home is new.  I'd say it was 1950's, perhaps - probably explains the wiring colours - all the sockets are IN the skirting boards, for example!

I don't know if the previous owners ever had power in the garage.  They themselves only had the house for a couple of years, so it may not have been them that had it installed.

Kerching ...  the garage CCU has the RCD, and two CB's.  The RCD was connected red into right hand top of the rcd (the supply?), the yellow into the earth bar, the blue into the neutral bar. All of this was already done.

The only connection I made was my temporary socket into the 20A CB.  blue into the neutral bar, brown into the top of the circuit breaker, I sleeved the earth wire green/yellow and connected this into the earth bar.  I wired up the temp pendant in the same way.  Both loads tripped the RCD.

well there's your problem

 

[ProDave]

well there's your problem

Well spotted.

the Blue coming IN from the main house CU should go the the other top terminal of the RCD, and not straight to the neutral bar.

That being the case, this has probably never worked, so dispels my previous theory of the last owner disconnecting it to avoid part P questions at the time of sale.