test rig with fault causing fault elsewhere

[jonthesparks]

:confused5: I have been asked to wire up a couple of CU on plug tops on a display for tenants to show how to go about basic fault finding before they send for a call out .
I used 2 wylex boards , one with dual rcd and one with none .
I put a neutral earth fault but that resulted in the plug top supply tripping out before the show CU tripped , so i changed the fault to live earth and still it tripped out the plug top supply .
any ideas on how to contain the fault to my test unit . I knew i should have paid more attention in college about discrimination .

 

[Thefailsafe2012]

Are you plugging the CU's into 30mA RCD protected sockets?

 

[jonthesparks]

no but the socket is protected by an rcd

 

[MarkieSparkie]

Separate the incoming supply from the portable CU test box(es) with a 230V/230V isolation transformer (similar to the more familiar 230v/110V yellow site transformer).

 

[Thefailsafe2012]

no but the socket is protected by an rcd

so it is RCD protected then lol! Either only use your rigs at places where they don't have RCD's or take a genny with you :walkman:

 

[Marvo]

.......or take a genny with you :walkman:

Pleeeeese don't apply a neutral - earth fault to anything that's plugged into a generator. Many small generators have split windings and with a neutral-earth fault you'll either make the chassis of the generator live (assuming it's not connected to an earth spike) or you blow the hell out of the windings.

I'd suggest rather go with Markiesparkie's isolating transformer idea.

 

[Thefailsafe2012]

Pleeeeese don't apply a neutral - earth fault to anything that's plugged into a generator. Many small generators have split windings and with a neutral-earth fault you'll either make the chassis of the generator live (assuming it's not connected to an earth spike) or you blow the hell out of the windings.

Sorry Marv, was a joke I promise!

 

[Marvo]

No probs, especially in the general public forums I thought it was best to clarify in case it was taken as a serious suggestion.

 

[Marvo]

To be honest I'd use a 12v battery or 12v pool light transformer and fit some indicator LED's but I'm not sure if the RCD would trip to a leakage fault with an ELV supply.

 

[dc-electrix]

I would see if you can use the transformer from a shaver socket, its cheap and cheerful and wont weigh you down. Do remember that you will only be able to run a very small load, but as you said its a test rig so no need for massive capabilities.

 

[trev]

Why can't the housing association/council just send people round when tenants have problems. This will encourage idiots to think "Well doing that was perfectly safe so this will be too"
It'll end in tears mark my words

 

[Sintra]

Basic fault finding should not be encouraged to any incompetent persons let alone a housing association or whoever wanting test rigs made up. All the tennents need to know is how to reset a mcb, RCD or rcbo. If it holds fine if not lift the phone. These people should not be encouraged by anything more.

 

[Knobhead]

I’ve come across some stupid ideas before. This ranks high in the list.

A housing association would not / could not encourage DIY repairs!

 

[jonthesparks]

It would seem that some people have got the wrong impression about what the aim of this test rig is about , to clarify , basically want to show the first steps , and the only ones necessary for tenants to put their supply back on in the case of say a lamp causing the rcd to trip out , thats it , no tools involved little brainpower required .

 

[Sintra]

You don't need a live rig with faults incorporated to show them that. A simple set of written instructions would do the job.