Fridge tripping.

[OhmSweetOhm]

Mates fridge in his shop keeps tripping after varying amounts of time between 10 and 30 minutes he has told me. It is running on a B32 breaker. Should it be a C type? For it to be running for at least 10 minutes before it trips does that mean i can eliminate the problem being high startup current (assumong fridges have one).

 

[chopper]

try a PAT test if its plugged in

 

[Sparky Ninja]

What's tripping, MCB or RCD?

 

[OhmSweetOhm]

Breaker

 

[Des 56]

If the 32 amp mcb is tripping, then either the mcb itself may not be functioning correctly or there is excessive load on that mcb or there is a short later in the function of the fridge

Is the circuit for the fridge shared by other loads ?
If so
How do you know that the fridge is the culprit ?
Could there be an overload of that circuit by the accessories connected

If its on its own circuit,what is the expected load of the fridge ?
Compressor faults simillar to that described ( delayed tripping) are usually neutral to earth faults that trip the Rcd
Has there been any testing carried out ?

Type c would help with start up currents of motors but no doubt it may be the wrong aproach to consider at first

 

[malcolmsanford]

If the 32 amp mcb is tripping, then either the mcb itself may not be functioning correctly or there is excessive load on that mcb or there is a short later in the function of the fridge

Is the circuit for the fridge shared by other loads ?
If so
How do you know that the fridge is the culprit ?
Could there be an overload of that circuit by the accessories connected

If its on its own circuit,what is the expected load of the fridge ?
Compressor faults simillar to that described ( delayed tripping) are usually neutral to earth faults that trip the Rcd
Has there been any testing carried out ?

Type c would help with start up currents of motors but no doubt it may be the wrong aproach to consider at first

Can't really add a lot to Des's post only to say that once you upgrade that B to a C your introducing a whole set of problems regarding disconnection times. The Zs for the circuit for a C is nearly half that required for that B, so before you think of changing it you'll have to make sure you can achieve the disconnection.

 

[Farmelectrics]

i thought the only difference with b and c type breakers was that b type are more sensitive than c type ie trip quicker wasnt aware of start up currents des please explain cheers des

 

[malcolmsanford]

If you have a copy of the OSG then have a look at pg 58 table 7.5 you will see that a B type will trip at 3-5 times it's rated current, so we normally for a modern MCB take the makers recommendation of 5 times so a 6 amp B will trip at 30amps on over current.

A C type as you can see will trip at 5 -10 and again as most makers state 10 we can see that a 6amp will take 60amps to trip.

Most motor, compressors have an inductive load and on start up will have what is termed "in Rush" currents. These can be many amps over the rated size of the MCB and so by utilsing a C type breaker it will avoid tripping.

The different ratings of MCBs were designed to avoid the use of larger than needed MCB's, larger than needed cables ETC for a start up over current that will last less than a second in most cases

 

[Chr!s]

Mates fridge in his shop keeps tripping after varying amounts of time between 10 and 30 minutes he has told me. It is running on a B32 breaker. Should it be a C type? For it to be running for at least 10 minutes before it trips does that mean i can eliminate the problem being high startup current (assumong fridges have one).

Is there an RCD protecting the circuit?

I would assume a fault on the fridge.

If the hermetics are blocked then this will place the compressor under a heavy load, a breakdown of the winding may be occurring, also check evaporator fan, circulating fan and defrost element, all these may be producing the fault.

 

[OhmSweetOhm]

Haven't been to look at the problem myself yet, just going on his explanation for the moment and trying to get a rough idea of what to look for.
Could the wiring of the circuit be the problem ie loose connections in the plug and socket(s)?
I'll get the make and model of the fridge when I go to have a look and browse the internet to check for the load it pulls.
If there's a compressor fault then that's out of my hands right?

 

[OhmSweetOhm]

UPDATE

Still haven't been to look, but he has just told me that he put the breaker back on today after leaving it off for a while I presume and it has held all day. Dodgy breaker or dodgy fridge it seems?

 

[steve k]

The problem has been the higher temp over the last couple of days. Today is cooler and the fridge works.

I bet the condenser coil is blocked and needs a good clean out. When the coils coils get blocked, the compressor will not work efficiently. The motor run times are too long and the compressor overheats, pulls too much current and...........you guys know the rest.

Tell your mate to ring a fridgeman to give it a good service.

Steve