Jump to content
Security Installer Community

Help - split load CU RCD tripping


Guest rafal

Recommended Posts

Just installed my DSC 832 and I have very strange electric problem.

The panel is connected to its own 6A mcb in the non RCD section

of the split load /one section with an isolator switch, other with an RCD/

consumer unit. As soon the mcb is switched on the RCD section trips out!!!!

So far I have found the following:

- works ok with the RCD section off

- it trips with the 832 transformer connected /panel disconnected/

- it trips with the earth wire disconnected

- tried different wire from the CU to the transformer

Link to comment
Share on other sites

If you look in the consumer unit you'll see there are 2 neutral bars. You've connected the neutral of the alarm supply to the wrong bar.

35222[/snapback]

Whoohaaa, result! It is bloody working!

Thank you, thank you, and thank you!!!!

You have just saved my sanity. I feel a bit like a plonker.

But if you do not know, you do not know.

After all I am an electronics engineer not an electrician.

But have no fear, I

Link to comment
Share on other sites

No probs, I've seen people do this many times over the years!

I once worked with a firm that had this subby on a job who changed a consumer unit and did this. By the time he'd finished he'd condemned half the appliances in the house and even meggered a couple of lightbulbs for earth faults before someone else pointed out the fault in the CU!

Link to comment
Share on other sites

No probs, I've seen people do this many times over the years

35250[/snapback]

Lurch you can fix mine now (that was easy). I have a TT system with an RCD MCB DB The intermittent tripping is a pain in the but. ive used insulation tester, issolated load the lot i recken som ferkin mouse is lickin the cable when im not there. Its been behavin itself for about a month and went again so shove it out with the RCD stuff the regs i want a constant supply.

Jef

Customers!

Link to comment
Share on other sites

Tricky one, hard to do a lot from here!

I'm a bit pushed for tiime at the mo but I'll try and give a more useful response later.

For a start, are any of the circuits looking dodgy from the results oif the megger?

If everything is on one RCD you could alter the DB so only certain circuits are on a 30mA RCD and the rest, such as lighting and non socket circuits etc.. are on a time delayed 100mA RCD.

Link to comment
Share on other sites

No probs, I've seen people do this many times over the years!

I once worked with a firm that had this subby on a job who changed a consumer unit and did this. By the time he'd finished he'd condemned half the appliances in the house and even meggered a couple of lightbulbs for earth faults before someone else pointed out the fault in the CU!

35250[/snapback]

Sometimes it is unbelievable what people can get away with and still call

themselves professional. People running around with a neon tester

insisting that the spur is ok when the neutral is burned out.

A senior Debenhams electrician moved a 3phase socket and rewired

lewden plug trying to much the colours of the flex cable and the solid core

cable in the socket /blue to blue!/ Lucky I check it before connecting 15k worth

of equipment. I made him a little explanation drawing.

He got very upset with me

Link to comment
Share on other sites

Interesting comments on electricians skills being made here. :unsure:

We had a faulty dishwasher that the engineers came back to many, many times. In the end we discovered that it had been built using a batch of faulty actuators (not sure what you call them, they're wax-filled and electrically heated to move valves) so different bits of it kept failing and shorting.

After a few visits and at least 5 replaced controllers one guy decided our house wiring was faulty and stuck a "unsafe do not use" label on the socket. He had "tested" it with some small device and said the earth impedance was too high. Quite how this would blow a dishwasher is beyond me; if it's working properly it won't touch the earth.

I hired a big tester myself and everything in the whole house was fine. The particular socket is right next to the consumer unit and earth point so got the best readings.

So we contacted the electicity board who came out, checked it all and said the earth was fine. They pointed out that as we have overhead supply the Neutral is actually earthed as well - at every other pole on the route they said. Their comments about the dishwasher engineer were unrepeatable. :realmad:

Of course this was an appliance engineer, not an electrician. The real professionals got it right! :D

Link to comment
Share on other sites

After a  few visits and at least 5 replaced controllers one guy decided our house wiring was faulty and stuck a "unsafe do not use" label on the socket. He had "tested" it with some small device and said the earth impedance was too high.

35363[/snapback]

AKA 'clutching at straws'!

Link to comment
Share on other sites

  • 5 months later...
Guest Sparking_mad
Lurch you can fix mine now (that was easy). I have a TT system with an RCD MCB DB The intermittent tripping is a pain in the but. ive used insulation tester, issolated load the lot i recken som ferkin mouse is lickin the cable when im not there. Its been behavin itself for about a month and went again so shove it out with the RCD stuff the regs i want a constant supply.

Jef

35264[/snapback]

Is your property a thatched cottage or similar?

If not is your C/U a split load board, has the cooker panel got a skt outlet on it, have you got a garage or other similar outbuilding which is outside the equipotential zone of the home ie is it seperated from the house. The reason will become apparent and its not because i'm nosey. I recently got a call to a rural cottage and found the voltage trip inoperative and replaced it with a 30mA rcd and promptly tripped so put in 100mA one instead but to no avail and now am going down the route of putting individual RCBO'S on all circuits supply skt outlets and 1st floor lighting points (dont like lights on rcds) for obvious reasons because of thatch and fires. On a TT system your earthing comes from the rod what was your Earth Loop Impedance reading in an ideal world should be less than 200Ohms but with rcd you can get away with 1666Ohms. How old is the installation.

Link to comment
Share on other sites

Is your property a thatched cottage or similar?

If not is your C/U a split load board, has the cooker panel got a skt outlet on it, have you got a garage or other similar outbuilding which is outside the equipotential zone of the home ie is it seperated from the house. The reason will become apparent and its not because i'm nosey. I recently got a call to a rural cottage and found the voltage trip inoperative and replaced it with a 30mA rcd and promptly tripped so put in 100mA one instead but to no avail and now am going down the route of putting individual RCBO'S on all circuits supply skt outlets and 1st floor lighting points (dont like lights on rcds) for obvious reasons because of thatch and fires. On a TT system your earthing comes from the rod what was your Earth Loop Impedance  reading in an ideal world should be less than 200Ohms but with rcd you can get away with 1666Ohms. How old is the installation.

54472[/snapback]

Looked at all of the above. I completely rewired the place two years ago. I have tested, tested, and tested again and cant find a fault. The problem with intermitent tripping is one trip about every 8 weeks. the problem is no one else is at the property when this happens. Ive tried issolating the usual suspects (both poles of each circuit a curcuit at a time) and still it goes. Its fixed now i just through th RCD away.

Jef

Customers!

Link to comment
Share on other sites

Looked at all of the above. I completely rewired the place two years ago. I have tested, tested, and tested again and cant find a fault. The problem with intermitent tripping is one trip about every 8 weeks. the problem is no one else is at the property when this happens. Ive tried issolating the usual suspects (both poles of each circuit a curcuit at a time) and still it goes. Its fixed now i just through th RCD away.

Jef

54493[/snapback]

Why have you thrown it away, could you not have linked it our with a rusty 4" nail just so you dont have a hole in the front of your DB ?

www.nova-security.co.uk

www.nsiapproved.co.uk

No PMs please unless i know you or you are using this board with your proper name.

Link to comment
Share on other sites

On a TT system your earthing comes from the rod what was your Earth Loop Impedance  reading in an ideal world should be less than 200Ohms but with rcd you can get away with 1666Ohms. How old is the installation.

54472[/snapback]

I know I'm diverting from the original subject, but is there a "standard" written down anywhere for ELI?

I ask because an appliance engineer said ours was too high and "probably" the cause of the fault he was fixing (no, I didn't believe him either). I think it was about 30 ohms via a rusty rod at the time. Anyway Southern Electric came and checked it, and as we're on overhead cables changed it around. They have earthing rods on every other pole apparently and linked it to those. It's now 0.15 ohm! Beat that! :yes:

Link to comment
Share on other sites

Guest IM_Alarms

Hmm try working at a power station if you want low readings........ 0.01/ 24kA+ meter doesn't go any lower/higher!

:stab:

Link to comment
Share on other sites

If you look in the consumer unit you'll see there are 2 neutral bars. You've connected the neutral of the alarm supply to the wrong bar.

35222[/snapback]

who says sparkys make the best alarm engineers... :whistle:

Link to comment
Share on other sites

re-appliance engineers,once had a fault with a new washer a relative bought kept tripping the rcd,called out (wont name names) blamed it on the spur supplying the washer,i was there when he turned up..' look he says the washer is live' with one lead on the live and the other the washer casing :no: after much laughing and holding groin area to stop urine leaking,he promtly left in shame....last seen rocking back and forth in a chair mumbling the words gaz and B******d

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.