Water pump - RCD tripping

[z00ber1979]

Hi All

Thanks in advance for the help and advice that forums like this provide, I appreciate everyone taking the time to read and respond.

I have a water butt that I want to pump from, and I’d like to put the pump on a timer.

I have two pumps - one is a dirty water pump, and has an RCD on the plug. The other is a specific “water butt pump”, and doesn’t have an RCD. I understand that having an RCD is for the best when mixing water with electricity.

I’d prefer to use the dirty water pump (more power, newer, safer?) but every time the power is switched off, the RCD trips. Using a timer would mean then that it would trip off every time the schedule ends.

Trying to find the best solution.

-Should I replace the dirty water pump on the assumption that it’s faulty?
-Could I replace the outdoor socket with one that has an in-built RCD and change the plug to a normal one plugged into a timer?
-Do we think the water butt pump is ok without an RCD?
-Any other bright ideas?

 

[ericmark]

There are two types of RCD plugs, active and passive, the active type will always open with loss of power.

The problem is the plug RCD needs a voltage over a set limit to work, in a consumer unit we can guarantee it will have enough voltage, but at the end of a long extension lead it may not.

But swapping the plug from active type to passive type is not likely to cause a problem. The risk is low. There may be another reason. With something like a grinding wheel, if one has a power cut, one does not want it to auto start when the power is returned, so the active RCD may be to stop you leaving the pump so it will auto start if power returns.

 

[z00ber1979]

Excellent, very helpful. Know exactly how to proceed now, thanks

 

[Harry Bloomfield]

I understand that having an RCD is for the best when mixing water with electricity.

Not best, but an essential - that the circuit is protected by an RCD!

 

[z00ber1979]

Not best, but an essential - that the circuit is protected by an RCD!

Quite. Weird that the pump made specifically for water butts had nothing, but I did buy it second-hand so maybe the instructions specified otherwise.
In any case, I’m going to change the outdoor socket to one with an in-built timer, change the active RCD plug to a normal plug, and install an in-line passive RCD rated for outdoor use.
Thanks folks

 

[jj4091]

Quite. Weird that the pump made specifically for water butts had nothing, but I did buy it second-hand so maybe the instructions specified otherwise.
In any case, I’m going to change the outdoor socket to one with an in-built timer, change the active RCD plug to a normal plug, and install an in-line passive RCD rated for outdoor use.
Thanks folks

Perhaps it should be controlled by a float switch. Leaving the RCD activated

 

[z00ber1979]

Perhaps it should be controlled by a float switch. Leaving the RCD activated

Thanks for the advice. I actually forgot to mention that the dirty water pump has a float switch, which is another reason for me preferring it over the water butt pump. So the final setup will have both passive RCD and float switch.

 

[Harry Bloomfield]

Quite. Weird that the pump made specifically for water butts had nothing, but I did buy it second-hand so maybe the instructions specified otherwise.
In any case, I’m going to change the outdoor socket to one with an in-built timer, change the active RCD plug to a normal plug, and install an in-line passive RCD rated for outdoor use.

I think you are misunderstanding - the entire circuit should be protected by an RCD, rather than the appliance being fitted with an RCD. That would provide protection for anything plugged into that outlet.

It is normal now to have the entire house, protected by a single RCD. Some have two RCD's splitting the loads over each, some now use what is called an RCBO, which is a combined RCD and MCB - one per individual circuit.

As mentioned by JJ, why are you running a pump, on a timer at all? Pumps running dry, wear out quickly, it is more usual to control them with level detection.

 

[ericmark]

Quite. Weird that the pump made specifically for water butts had nothing, but I did buy it second-hand so maybe the instructions specified otherwise.

Not at all. Today most supplies are RCD protected at the consumer unit, and there is no need to double up on RCD protection, with one or two exceptions, caravans and boats, where both the supply has an RCD and the caravan or boat has an RCD. So unless 10 mA rather than 30 mA there is in the main nowhere that an RCD plug is required.

I do have two RCD sockets fed from an UPS (uninterruptible power supply) for fridges and freezers, but the rest of house protected by RCBOs at the consumer unit (CU) the British Standard and type required it seems hard to find as a plug, they tend to have been designed before 2008 when the rules required RCD protection for most fixed wiring.

 

[z00ber1979]

Thanks all for the input. I’ll try and clarify and summarise

I have a greenhouse away and uphill from the house. Having tried various options, the best scenario for me is to irrigate from the water butts (next to the house), using a pump on a timer.
The dirty water pump I’d prefer to use for the job has an RCD integrated into the plug, and trips whenever the power cuts out (rendering it useless with a timer)
From everyone’s input, I’m supposing now that I can replace the RCD plug with just a normal plug, use a timer via the waterproof outdoor socket, and rely on the the household consumer unit (which is fairly new) to provide protection in the event that the pump has an underwater electrical fault. There is no need to provide an individual RCD for the pump. The float switch will make sure it doesn’t activate when the water is low.

 

[ebee]

You can have RCDs that are either Latching or Non Latching too on portable appliances so that can make a difference if your supply is switched off.
In most circumstances you need an RCD to latch to on if it is switched by a timer, providing it is safe to restart (it would not be safe for a portable drill to switch on if you were holding it and somebody or something (Timer example) has switched it back on, would it?

 

[CountryFan]

Maybe provide the make and model of pump so we can read up on it?

 

[z00ber1979]

Instructions below. If the link doesn’t work, it’s a titan TTB844PMP 750w dirty water pump. I’m happy to replace the plug RCD with a passive (latching) in-line one instead, but won’t if people don’t think it’s needed.

https://www.free-instruction-manuals.com/pdf/pa_2655831.pdf

 

[ericmark]

Although I have used an active RCD as a no volt release unit, that is not what they are designed to do. In some cases it can cause danger, I had it where a mag mount drill fell off due to loss of power, the required chain stopped it falling to the floor, but it still dropped a foot or so.

OK, other factors as well, the generator dropped to tick over as the magnet not drawing enough current, so a work lamp bulb failing caused it to drop.

But you must do the risk assessment, I don't mean writing out a form, but look at what might happen, if the pump is auto powered up. Be it soak the cat lying on plants, or something which is not quite as funny. Cycling, I was not amused when an irrigation started up as I was passing it. Should have realised that was why the road was wet, but I didn't until too late.

 

[z00ber1979]

Risks associated with it turning on at an unexpected time are minimal, but thank you for the advice.

Soooo, do I need to replace the active RCD plug with an in-line passive RCD? Or just change the plug to a normal one and crack on? The only real concern I have is whether I’m going to get electrocuted if there’s an issue and I stick my hand in the water butt