power ring fault....

[matt.leung]

got a strange one...

got a phone call today as there is an issue with the power circuit...

on this ring circuit as soon as they plug in two or three items of equipment there is loose of power. The client has already tested the circuit and with no load it reads 240v, and after three or so items are plugged in it drops to 4volts. None of the mcb's trip at all...

the client thinks that there is a loose connection some where, i am thining it could be a borrowed neutral.... any ideas..

going to have a look tomorrow afternoon....

:run

 

[Apache]

Interesting. What are they plugging in? This isn't the symptom of a borrowed neutral. Are they using high drain appliances?

 

[matt.leung]

they are plugging in the computer, and internet router, and a desk lamp... ---- but why the differance in voltage, and nn mcb tripping so it cant be an overload..

 

[Evans Electric]

I,m thinking loose connection here .

 

[batty]

Could be a loose connection in phase or neutral. Mcb will not trip as it is not being overloaded. I assume there is no RCD on circuit.

 

[Lee321]

2 spot on diagnosis above

opps 3

 

[matt.leung]

i have been told that it is a new CU, so there should be an RCD... they have had a couple of new sockets installed, and the client has had a look and can not see any loose connections, he thinks there could be one under the floor... but wants me to narrow it down... how the hell could i do that, IF there is a loose connection...

 

[Lee321]

well you disconnect at the half way point and load up the circuit

if the same happens its in the first half if not the second. then then process starts again

 

[Doc Hudson]

they have had a couple of new sockets installed, and the client has had a look and can not see any loose connections.

I doubt they will be able to identify lose connection by just looking. They need to get a decent screwdriver and have a go at actually tightening everything up. It's not uncommon for connections made by DIY persons to be left only just gripping the conductor. I assume this is DIY work, or they would be calling back the original electrician?

Doc H.

 

[initforthemoney]

An r1, rn test will show up bad connections.

Sorted.

 

[Riggy]

got a strange one... got a phone call today as there is an issue with the power circuit...

on this ring circuit as soon as they plug in two or three items of equipment there is loose of power. The client has already tested the circuit and with no load it reads 240v, and after three or so items are plugged in it drops to 4volts. None of the mcb's trip at all...

the client thinks that there is a loose connection some where, i am thining it could be a borrowed neutral.... any ideas..

going to have a look tomorrow afternoon....

:run

initforthemoney is bang on for loose connections, but the following intirigue me:

1. If it really is a ring how many loose connection would you need to create the symptoms?

2. Your borrowed neutral theory is interesting, how would that work?

3. How many sockets are affected (or are all the items plugged into one socket)?

 

[sparkytim]

As others have suggested this sounds like a high resistence connection either on the Line OR nuetral, seems ok untill any Load draws current.

Is it ONLY one circuit?

If so fully check connections starting from supply end, maybe even faulty MCB or Nuetral connection.

If ALL circuits do the same then check Main Switch terminals IF nothing found then suspect Supply equipment ( Meter / service fuse / supply Cable) fault call DNO.

 

[muffin]

the three items seem likly to be from the same area.

maybe same socket

maybe same 4 way adaptor with surge protection, and maybe this is dropping out.

but then again .....

you need to find out if the sockets all loose power or just one.

 

[matt.leung]

I have been round to take a look, and found that the ring has been extended in connector block, and the N connection has melted and on of the conductors was arching out, in other words there was a sign of a small electrcial fire.....

 

[SteveT]

Well done mate - you may have saved a life or two

Sometimes its best to check everything visually as well as by testing

You can always rebuild from CU/DB

 

[a1]

Thanks for the update, Matt.Leung