Problem with caravan RCD unit???

[David_from_Ashby]

Hi All

On a couple of recent winter trips away we started having problems with the caravan RCD tripping. Usually this occurs with the caravan blown air heating running and a small fan heater in the awning. The fan heater is fine and does not have an electrical problem but after say an hour or two of use, the RCD in the caravan trips out on the mains socket circuit. If I then reset it, it will work for a while longer before tripping out again.

Do RCD units in carvans need replacing every few years? Does the life in a mobile van give them a hard time? I certainly don't have to change them at home. Any ideas if this is the problem?

The RCD unit is in the wardrobe in the (usually cold) end bathroom of a 2001 compass corona, so I am sure overheating of the RCD itself is not the problem.

Does any one else have a similar problem?

Cheers

David

 

[gary]

You say the 'socket circuit' trips out. this then is an MCB that's tripping and not the RCD.

So it depends on the total amperage load on that MCB and whether that's greater than the MCB can take.

If it's less then the MCB alone needs replacing, if it's greater then it's overloaded and doing it's job correctly.

One other reason is a poor connection to the individual MCB, this will cause it to overheat which will also trip it out.

 

[Parksy]

Hi David

When you mention that you run a small fan heater in the awning where is it connected? Have you got an outside socket on the n/s of the caravan and could you be overloading the socket circuit with your fan heater, tv and possibly kettle? Do the 240v lights and the fridge stay on?

 

[J.Lo]

I was just wondering, will you be still trying to warm the night air with a small fan heater when your power is metered, or will you get a bigger heater.

 

[David_from_Ashby]

Hi All

Thanks Gary, it is an MCB that is tripping, which knocks out all the 240v sockets. We are talking about a 1.5kw heater running on only half power to around 750w. Well wiothing the MCB capability. Incidentally, the MCB is fine for relatively short periods of the heater running on Max as well as a microwave running.

I will look at replacing the MCB unit and see if that helps.

Cheers

David

 

[JTQ]

I am intrigued by you statement

"We are talking about a 1.5kw heater running on only half power to around 750w."

Obviously you know what your unit is and I don't, but what fan heaters actually reduce the instantaneous power consumption?

All those I know of switch the "full" power of one or more elements on and off.

So I suspect it is pulling either 1.5 kW or zero even if turned down, unless its a multi element unit.

 

[David_from_Ashby]

I am intrigued by you statement

"We are talking about a 1.5kw heater running on only half power to around 750w."

Obviously you know what your unit is and I don't, but what fan heaters actually reduce the instantaneous power consumption?

All those I know of switch the "full" power of one or more elements on and off.

So I suspect it is pulling either 1.5 kW or zero even if turned down, unless its a multi element unit.

Hi JTQ

A simple answer really, the fan heater has three heat settings, cold air only, 1 bar (750W) and 2 bar (1.5kW). If i runit on 1 bar it uses approximately half the power that 2 bars pull (neglecting the difference due to the fan running in all three modes).

CHeers

David

 

[gary]

An MCB is designed to cope with overloads before tripping, the amount of overload is defined by the letter before the amperage.

'B' is the common 'domestic' grade and takes 1.45 the stated amperage for as much as 20 minutes, 'C' & 'D' grade, designed more for industrial motor start up currents, take much more overload but for far shorter periods.

As a crude example, switching on a Hoover running at 6A but with a 12A start current, a B6amp will trip while a C6amp will probably cope.

So it depends in this case what the MCB's rating is and what the total load is, 750w is 3.3A but don't forget Microwave input currents are far higher than stated outputs?