Discuss Water Pump requires Type A differential switch (RCD?)! in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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I am installing a DAB Divertron 1000 water pump in a rainwater harvesting tank and was surprised to discover that the enclosed "Safety Instructions" booklet states "The differential switch protecting the system must be correctly sized and must be of the "Class A" type. It must guarantee disconnection on the event of a category III over-voltage." The booklet has "EN 60335-1" on the cover (EN 60335-1 relates to the European Low Voltage directive).

A Schneider A9R21225 looks like it may be a suitable item, although my pump supplier, thinks they normally connect to an ordinary fused spur, rather than using any special breaker.

Can anybody cast any light on this requirement. I have so far been unable to find the text of EN 60335 - 1.
 
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plugsandsparks

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Think its a bit OTT for a sub pump. 5 amp FSU off a 30mA RCD is more than enough. If you want to add a SPD to protect the sensitive electronics, by all means.
 

Lucien Nunes

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Yes it looks like poor translation but surely just means a type A RCD. DAB pumps being Italian, it would have have started out as 'interruttore differenziale'. They spec type A because the pump contains integral electronic controls, so could produce a pulsating DC fault. Normal RCDs in distribution boards are designed to meet category III requirements, whereas plug-in ones might not.
 
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Thanks Lucien. Looks like I am going to have to buy a new consumer unit. BG don't appear to do type A RCDs, but hang on a minute don't many household items include "integral electronic controls", why are they OK on a type B RCD and not the pump?
 

Lucien Nunes

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I think you mean type AC (Type B are the all-singing, all dancing ones that can detect everything). Theoretically, any appliance with electronic speed control, lighting dimmer or other electronic device that can chop the current waveform assymetrically, can create fault conditions that won't trip a type AC. In practice, most dangerous leakage faults are from damaged flexes, plugs, wet appliances etc so will tend to be true AC leakage at 50Hz and will correctly trip a type AC. In the case of the pump, as a likely fault mode would be water ingress into the motor, which is downstream of an electronic speed control, it makes sense for them to spec an RCD that will respond to that situation as well as the more common chafed cables and wet terminal boxes.
 

davesparks

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Thanks Lucien. Looks like I am going to have to buy a new consumer unit. BG don't appear to do type A RCDs, but hang on a minute don't many household items include "integral electronic controls", why are they OK on a type B RCD and not the pump?
I think you may be getting RCDs confused with MCB's which are commonly found in B type in domestic installations.
Type B RCDs are pretty rare and a bit of a specialised item, type AC is the most commonly available type. Many things include electronics as you say, and many of them would probably be better off on type A RCDs, this is why the regulations have changed to reflect this.
 
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Thanks both. You were spot on re type B vs AC, thanks for pulling me up on that. Appreciate the expanded explanation too Lucien
 
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