RCD spur trips whole house

[Taylortwocities]

PICTURES

we need
PICTURES

of the consumer unit and the main switch.

Thanks

 

[10monty]

I will try and get some posted up tomorrow

 

[ban-all-sheds]

Made me wonder if this is TT with an ELCB or RCD before the CU?

If it is TT, let's hope it is before...

I have a metal Wylex ...

 

[sparkwright]

Thanks for all your input, it seems I have completely wasted my time in doing this.
I do indeed have a test button on my consumer unit, which I had never even noticed before, so I will swap the rcd spur for a standard one.

I had a sparky round a couple of months back to quote me for a new board and he said the existing one wasn't rcd protected. Guess he was just trying to coax me into getting it done sooner rather than later.

Thanks again for your help.

You don't say if the RCD on the consumer unit is 30 mA or 100 mA (or something else).

 

[bernardgreen]

If your main switch is an RCD then pressing the test button on the external socket WILL trip the main switch as it will see it as a fault condition.

In theory the pressing the test button on an RCD should NOT trip an upstream RCD as the test button does not ( on a normal ) RCD create an earth fault. It creates an unbalance by connecting a resistor between Live after the sensor and Neutral before the sensor creating the test current on only the Live through the sensor. Some RCD test buttons may create a fault to earth but that would require an earth connection to the RCD. An RCD incorporated into a socket would have an earth connection available.

 

[10monty]

Ok here are the pics.

View media item 35989 View media item 35992

 

[sparkticus]

OK you do have an RCD. It is designed to trip when a leakage current equal or greater than 100mA is detected. In reality it will probably trip at much lower leakage. A 30mA RCD on the same circuit as a 100mA RCD rarely displays any discrimination and both usually trip under fault conditions. As bernardgreen has suggested, your socket RCD probably connects live with earth (through a resistor) to cause a trip current when you press the test button. That test current also causes the main 100mA RCD to trip because it "sees" that leakage current.

Both RCDs will most likely trip during a real fault.

 

[Taylortwocities]

OK. That makes sense.

You have an RCD on your consumer unit. That is the main switch but it is rated at 100mA. That provides a very basic level of safety for the installation but protection for the socket needs to be 30mA to provide an acceptable level of personal protection (eg lawn mower running over cable, etc).

So the 30mA RCD you have installed will provide that.

The problem is that the main switch RCD will trip if there is a fault of more than 100mA so it may trip - as well as the 30mA rcd - in the event of a fault or (it seems) when you press the test button.

There is a way round it but it would be expensive and may cost more than upgrading your consumer to one with RCDs on all circuits.

My advice. Leave your 30mA fused spur in place and make a plan to get your installation upgraded.

 

[xr4x4]

OK. That makes sense.

You have an RCD on your consumer unit. That is the main switch but it is rated at 100mA. That provides a very basic level of safety for the installation but protection for the socket needs to be 30mA to provide an acceptable level of personal protection (eg lawn mower running over cable, etc).

So the 30mA RCD you have installed will provide that.

The problem is that the main switch RCD will trip if there is a fault of more than 100mA so it may trip - as well as the 30mA rcd - in the event of a fault or (it seems) when you press the test button.

There is a way round it but it would be expensive and may cost more than upgrading your consumer to one with RCDs on all circuits.

My advice. Leave your 30mA fused spur in place and make a plan to get your installation upgraded.

Good advice,

Also I'm assuming that the new sockect actuallly works?

 

[Alarm]

Agreed, how have you tested it?

 

[10monty]

I'm assuming you mean do I know the new rcd spur works. In answer to that no I dont, and I guess I wont until its too late. For now. I thinl I will replace it with a standard fuse spur and get my board updated sooner than I was going to. Thanks for all your comments, appreciated.

 

[xr4x4]

I'm assuming you mean do I know the new rcd spur works. In answer to that no I dont, and I guess I wont until its too late. For now. I thinl I will replace it with a standard fuse spur and get my board updated sooner than I was going to. Thanks for all your comments, appreciated.

I wouldn't, leave it as it is.

I meant, does the socket actually work?

 

[10monty]

Sorry yh the socket works ok

 

[securespark]

Also, you have tails that are not RCD protected entering a metalclad CU. Let's hope it is not a TT supply as said earlier.

As regards the spark, I don't know why he didn't try to coax you into having a new CU by telling the truth.....

 

[Alarm]

Sorry yh the socket works ok

How do you know?
By plugging in something?

What?