Previous in Forum: Electrical Heater for Closed Drain Vessel Offshore Platform   Next in Forum: Dot Matrix
Close
Close
Close
17 comments
Associate

Join Date: Sep 2010
Posts: 45

Single Phase RCD Type C/Breaker

04/12/2012 12:29 AM

I did the installation almost 9 yrs ago (residential house). The ckt comprises 1-phase CB. Two weeks ago, my client informed me about frequently triping of CB. He said, it can trip 2 times or more per day. If he restore it, it works for some hrs and the action repeats. I assigned technician to go at the site and did the following: opening all JB terminals and reterminate them, check the water pump terminals and reconnect it; also performed physical inspection of the installation. He did not see the tangible problem. On friday, 6.04.12, my customer called me again, telling that the CB was totally failed, and off course the problem was persisting, he said. The technician attended the problem, by using test lamp he discovered that the CB terminals was not conducting power.He replaced the same and new one, the ckt was put in operation and worked properly. After some hrs,the CB started triping as the first one, it is still in operation.

PLEASE help!

Register to Reply
Pathfinder Tags: rcd single phase c/breaker
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Commentator

Join Date: Oct 2011
Posts: 95
#1

Re: SINGLE PHASE RCD TYPE C/BREAKER

04/12/2012 1:20 AM

CB trips when more ampere flows through it. If CB is 40A and ampere flowing thru it is more. After some time CB will trip . This is thermal tripping. If you energise , it will work till the temperature rises to the tripping thermal temperature.

The solution is increase the ampere rating of CB. But take care the wire/cable capacity. If more current passes though you wire, it will burn.

Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 30332
Good Answers: 818
#4
In reply to #1

Re: SINGLE PHASE RCD TYPE C/BREAKER

04/12/2012 5:31 AM

<...The solution is increase the ampere rating of CB...>

The solution is to find out what has changed since the CB started tripping, and correct it!

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply Score 1 for Good Answer
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 467
#5
In reply to #4

Re: SINGLE PHASE RCD TYPE C/BREAKER

04/12/2012 7:51 AM

Agreed. This could be as simple as a loose ground or neutral in the panel, or may not be the circuit at all, but a fault in one of the appliances that are hooked up to it. Boosting the CB rating is literally playing with fire.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 30332
Good Answers: 818
#2

Re: SINGLE PHASE RCD TYPE C/BREAKER

04/12/2012 3:05 AM

If it is a residual current device, check that there is no path between earth and neutral downstream of it. If there is, then there is a fault downstream of it; rectify the fault, for that is what the device is indicating.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Guru

Join Date: Jun 2010
Location: srilanka
Posts: 2725
Good Answers: 5
#3

Re: SINGLE PHASE RCD TYPE C/BREAKER

04/12/2012 3:06 AM

How many outgoing circuits are connected to the RCD/CB?. Megger each circuit and also measure current in each circuit when carrying load. When it trips if you can't switch on again switch off circuits one by one and isolate the fault.

__________________
pnaban
Register to Reply
4
Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1610
Good Answers: 61
#6

Re: Single Phase RCD Type C/Breaker

04/12/2012 6:44 PM

Have you thought of using an amp meter to measure the amperage on the circuit? That might tell you something. Just a thought.

Register to Reply Good Answer (Score 4)
Participant

Join Date: Mar 2012
Posts: 3
#7

Re: Single Phase RCD Type C/Breaker

04/12/2012 11:31 PM

Many years have passed since installation of this single phase breaker. To remedy the problem, replace the breaker, with a similar one. Over time, the bi-metal strip will weaken causing it to trip. Also over time the load on that circuit may have been increased. The breaker is there to protect the circuit from over voltage and high amperage draw usually causing a high heat in the wiring. Double check the usage and replace the breaker.

Register to Reply
Associate

Join Date: Jul 2011
Posts: 48
Good Answers: 1
#8
In reply to #7

Re: Single Phase RCD Type C/Breaker

04/13/2012 3:08 AM

Just to confirm these devices do not protect against over voltage, they only detect current It's possible that the RCD side is failing or indeed there is actually a fault on the circuit. I would change the device and rule that out first

Register to Reply
2
Power-User

Join Date: Nov 2011
Posts: 286
Good Answers: 15
#9

Re: Single Phase RCD Type C/Breaker

04/13/2012 3:47 AM

Hi

Had a similar problem with an RCBO (combined MCB and RCD).

In my case it was a 32A ring main circuit. The circuit would run for anywhere between 30 mins to a few hours.

I was able to test everything plugged into the circuit and everything proved ok.

The ring was disconnected and a 500V megger used to prove the wiring. Turned out one of the cables had started to be break down and although had a resistance of a few thousand ohms under test was in trouble.

This has happened twice now - one where the cable was under a concrete slab so had to be abandoned and the other where it got against something hot and degraded.

Time to test the wiring.

Register to Reply Good Answer (Score 2)
Power-User

Join Date: Jan 2008
Location: New Hampshire
Posts: 106
Good Answers: 3
#10

Re: Single Phase RCD Type C/Breaker

04/13/2012 8:04 AM

The key to this is, the OP said water pump. I would start checking there first. If the breaker is tripping thermally, the pump must be drawing excessive current. Not enough to trip instantly, but enough to cause the breaker to heat up. If it is an RCD, then the motor may have an insulation problem. Just my 2cents.

__________________
rrnut-2
Register to Reply
Power-User

Join Date: Nov 2011
Posts: 286
Good Answers: 15
#11

Re: Single Phase RCD Type C/Breaker

04/13/2012 8:17 AM

If the pump tripped on a short circuit it would trip the breaker and show over. For it to take its time it would suggest its pulling about 50 or 60 amps. I don't know whether we are 110V or 230V but even at 110V its some mother of a pump to be running in a domestic environment. A simple ammeter tong test over wiring will sort this and take it out of the equation.

You have virtually eliminated the possibility of a faulty breaker by swapping it.

Its possible the pump is breaking down. Is it double insulated - many are. If it is it won't have an earth path back.

My bet is a failing cable.

Register to Reply
Power-User

Join Date: Nov 2007
Location: Dominican Republic
Posts: 278
Good Answers: 10
#12

Re: Single Phase RCD Type C/Breaker

04/13/2012 9:25 AM

Use a fluke clamp meter with min/max amp reading.

Register to Reply
Guru

Join Date: Jun 2006
Location: Ottawa Canada
Posts: 1975
Good Answers: 117
#13

Re: Single Phase RCD Type C/Breaker

04/13/2012 2:17 PM

I had the same problem with a hot tub I was called in to fix. It was a very expensive circuit breaker...a two hundred dollar dual phase GFI. Same symptoms exactly. We also changed the GFI, and the symptoms did not go away.

The fix was...clean and dry the pump area. Install ventilation.

It was stray leakage current which was the problem.

A similar problem on the airplane I was told to fix turned out to be a wire in a wire bundle which was chaffing. I figured it out suddenly when I discovered that the breaker would trip every time a technician walked to the back...flexing the underfloor wire bundle. A real bxxxxx to find, but easy to fix once we found it.

Two possibilities. I bet there are more.

__________________
If it was easy anybody could do it.
Register to Reply
Commentator

Join Date: Aug 2010
Location: alabama
Posts: 81
#14

Re: Single Phase RCD Type C/Breaker

04/13/2012 4:55 PM

Well dont know if theres much left to say. Except I would like to think the wire should be ok being only 9yrs old, check anyways. I maintain a sWmill that still has rubber and paper insulated wires in the office area and still ohms 100+ megohms. Breaker maybe weak, check with another circut. And I personally think the water pump probably has bearings going bad to cause the thermal trips or could be something restricting the flow of water causing back pressure, assuming the pump doesnt hVe a relief on it I would think so since its a 110v pump(sounds to cheap to hVe one) thats just what the maint. man in me is thinking. Oh and since u changed the breaker and its still doing it I say pump.

__________________
MattJohnson
Register to Reply
Commentator

Join Date: Oct 2011
Posts: 95
#15

Re: Single Phase RCD Type C/Breaker

04/14/2012 1:37 AM

MR. Thobias,

Did you solved it ?

Register to Reply
Associate

Join Date: Sep 2010
Posts: 45
#17
In reply to #15

Re: Single Phase RCD Type C/Breaker

04/16/2012 7:48 AM

Not yet sir,because I was out of city.But I hope from all these directed instructions I will rectify it.Thax very much u all .

Register to Reply
2
Power-User

Join Date: Feb 2009
Posts: 176
Good Answers: 6
#16

Re: Single Phase RCD Type C/Breaker

04/15/2012 1:34 AM

This is an RCD breaker so in my opinion an earth fault is more likely to be the problem If the pump is plugged into an outlet & outside several things come to mind

1st has your technician used a insulation tester / meg ohm meter meter on the circuit to confirm there is no fault in the circuit

2nd have you checked the outlet &/or junction boxes as ants love making nests in the back of them this has been a problem many times for me in the past especially at the start of the wet season

3rd Have you tried running the Pump on another circuit with an extension lead if so does the original circuit or new circuit trip ?

4th Is there any other loads on the circuit apart from the pump ? such as a fridge that can cause this random tripping because of cyclic defrost ect

finally has any 1 added any thing to the circuit since you installed it like another outlet or an appliance as I have seen this done by home handyman & it has been below standards & caused faults

Register to Reply Good Answer (Score 2)
Register to Reply 17 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

3PhaseDesign-Craig (1); arifkunnath (2); brettj1au (1); DGCYS (1); kramarat (1); MattJohnson (1); pnaban (1); PWSlack (2); rrnut-2 (1); silverfox (2); swschenk (1); THOBIAS MABUGO (1); wareagle (1); Yusef1 (1)

Previous in Forum: Electrical Heater for Closed Drain Vessel Offshore Platform   Next in Forum: Dot Matrix

Advertisement