Electricians in the house?

[surveyor]

Fitted a new pump at the weekend. The spec show an input power of 1.3KW and an output power of 1.1KW. The pump is a third more powerful than the one it replaced, but this was ancient and I suspect used just as much power....

We also have a old three door under bar fridge.

They co-existed fine for two days, but will no longer do so. Earth breaker goes if they are on at the same time. Turn one off and all is good.

Any suggestions of what the problem may be. Its's the fact that they were happy to co-exist for two days that has confused me.

PS - I know my limits so will not be re-wiring anything myself!

Edited by surveyor on Monday 21st April 08:42

[Neil - YVM]

What do you mean by 'Earth Breaker'?

The consumer unit will probably have miniture breakers for each circuit, which trip if overloaded, and 1 or 2 RCD Trips, which are the main ones for the board, but also detect earth issues.

From what you describe, it sounds like your larger pump, is now overloading the circuit and therefore the mcb is tripping.

[R1 Indy]

By earth breaker, do you mean the MCB breaker, or the RCD?

1.3 KW is only around 10Amps, so can't see it being overloaded, depending how its wired?? Are they just into a normal 13A socket on a ring main?

[surveyor]

Ok. We have two consumer units. The second is in an extension, this has breakers for separate circuits eg pump, sockets etc. this is then linked somehow back into the main consumer unit. I forget its name, but the breaker that is popping is a two gang type in the middle with lighting to one side and power the other.

What confuses me is that they all worked happily at first.....

[897sma]

R1 Indy said:

By earth breaker, do you mean the MCB breaker, or the RCD?

1.3 KW is only around 10Amps, so can't see it being overloaded, depending how its wired?? Are they just into a normal 13A socket on a ring main?

5.5 Amps.

[surveyor]

897sma said:

R1 Indy said:

By earth breaker, do you mean the MCB breaker, or the RCD?

1.3 KW is only around 10Amps, so can't see it being overloaded, depending how its wired?? Are they just into a normal 13A socket on a ring main?

5.5 Amps.

Fridge is a plug. Pump is hardwired on its own breaker, but that's not what's popping

[surveyor]

897sma said:

R1 Indy said:

By earth breaker, do you mean the MCB breaker, or the RCD?

1.3 KW is only around 10Amps, so can't see it being overloaded, depending how its wired?? Are they just into a normal 13A socket on a ring main?

5.5 Amps.

Fridge is a plug. Pump is hardwired on its own breaker, but that's not what's popping

[897sma]

If it's the MCB that's tripping then it's either overloaded or there is a short, those are the only things which will trip. If your RCD is tripping then there is likely to be a fault with the appliances or the way they're wired. Are you sure they're connected up correctly? Does it matter which you switch on first?

Edit to add. The RCD won't trip for no reason, there is definitely an issue which needs to be sorted.

Edited by 897sma on Monday 21st April 09:57

[surveyor]

897sma said:

If it's the MCB that's tripping then it's either overloaded or there is a short, those are the only things which will trip. If your RCD is tripping then there is likely to be a fault with the appliances or the way they're wired. Are you sure they're connected up correctly? Does it matter which you switch on first?

Nope. On their own both are fine. However add either to the other and it will trip.

[897sma]

And it's definitely the RCD & not the MCB?

[surveyor]

Definitely



Progress in that the shower also tripped the earth breaker. But all has now decided to play happily thereafter

Very very strange. I wonder if the pump was too hot and needed to cool down.

[hairyben]

Thats a powerfull pump, what's it for?

Earth fault circuit breakers are rated at 30mA and typically trip at over 20mA leakage to earth. Earth faults can "add up", if you have 3 appliances all leaking 10mA each they'll work fine with one or even two on but 3 will trip it, so older pre-existing faults can come into play too.

A conventional insulation tester is no use for appliances, A PAT tester can be usefull in this instance as you can test things while in use for earth leakage, I instead use a low reading (1mA resolution) clamp meter. You might find that something you haven't evan considered elsewhere in the house is adding to the issue.

Personally I try to steer everyone to RCBO circuit breakers especially for bigger installations or potentially nuisance loads, here you combine the functions of the MCB (individual circuit) and RCD, rather than having several circuits controlled by one RCD, but this is rare as it costs a little bit more.

[surveyor]

It's for a swimming pool... I'll have a look for a PAT tester. Can't hurt to have one in my work bag either. (An example is a client who rang to say they had no power in one of their offices. Was about to call the electricians, when I decided to call them first. Turned out they'd just bought a kettle. Unplugged it and no problem - the link should have been obvious!).

[hairyben]

surveyor said:

It's for a swimming pool... I'll have a look for a PAT tester. Can't hurt to have one in my work bag either. (An example is a client who rang to say they had no power in one of their offices. Was about to call the electricians, when I decided to call them first. Turned out they'd just bought a kettle. Unplugged it and no problem - the link should have been obvious!).

Yeah I should probably have one myself, trouble is I get about one or two actual PAT enquiries a year so it'd be yet another box of electronics that'd barely pay for itself or it's annual calibration costs before being swiped by crackheads.

Anywhere water and electric come together tends to be your first place to look for earth leakage but old compressors are far from trouble free too. Give some thought to RCBO's if the place is a keeper, if nothing else it narrows down the nuisance of earth faults.