Rcd or not?

grousedogtom

Hi,just a quick question , i fit a good few submersible pumps in bored wells where i connect the control box from a local socket that would be fed through an rcd,over time an odd motor in the well will cause the rcd to trip and by taking the pump off the rcd and just leaving it on an mcb it will work away fine for years to follow with no problems,strictly speaking should such pumps be protected by rcds?

M cebee

prob yes
it's in et101 2008 domestic pumps must have rcd
think that prob applies here

stating the obvious but-the rcd won't trip unless theres a fault

grousedogtom

OK I seem to agree but it's hard to justify pulling up a pump from maybe 400 foot to find such a fault, could it be possible a 30ma rcds could be too sensitive protecting a motor at such depths in water?

2011

grousedogtom wrote: »

strictly speaking should such pumps be protected by rcds?

If the pump is 400 feet down a well I do not see how an RCD would make make any contribution to the safety of the installation.

As M cebee says it should not cause an RCD to trip unless it is faulty. I would imagine that over time moisture works its way into the pump and will start to cause an RCD. The pump would normally operate with a small amount of leakage current.

I have heard that domestic pumps now require RCD protection in ET101:2008, but I have not seen it (yet). However I would be surprised if it applies in this case, especially when there is no risk of direct contact with the pump itself and it is quite separate to the house. I am open to correction on this.

If it is determined that the unit must have RCD protection then I would suggest that it is put on a dedicated RCD. This will reduce the likelihood of it tripping and prevent the loss of the pump effecting other circuits.

leeomurchu

2011 wrote: »

If the pump is 400 feet down a well I do not see how an RCD would make make any contribution to the safety of the installation.

As M cebee says it should not cause an RCD to trip unless it is faulty. I would imagine that over time moisture works its way into the pump and will start to cause an RCD. The pump would normally operate with a small amount of leakage current.

I have heard that domestic pumps now require RCD protection in ET101:2008, but I have not seen it (yet). However I would be surprised if it applies in this case, especially when there is no risk of direct contact with the pump itself and it is quite separate to the house. I am open to correction on this.

If it is determined that the unit must have RCD protection then I would suggest that it is put on a dedicated RCD. This will reduce the likelihood of it tripping and prevent the loss of the pump effecting other circuits.

+1 on this sound advice. Connect the pump into it's own RCBO at least you won't lose other services when it trips. 400 feet down? what cable have you got the pump wired in?

M cebee

ya bit late for me-cough
i think the issue with domestic pumps is leakage current rather than direct contact

grousedogtom

I've fitted submersible pumps anywhere between 10 foot up to 500 foot always using 4 core ho7 type cable, the size of the cable can vary from 1.5 up as far as 10 sq depending on depth of well and distance from the well to the power source, given the full length the cable size is then determined by the motor manufacturers chart.

2011

Can anyone show me where in the ETCI regulations it states that pumps must me on an RCD?
I am not suggesting it is not there, I just want to see if it applies in this case. I suspect it won't apply.

M cebee

2011 wrote: »

Can anyone show me where in the ETCI regulations it states that pumps must me on an RCD?
I am not suggesting it is not there, I just want to see if it applies in this case. I suspect it won't apply.

the rule i was thinking of is in the water heating appliance section so that doesn't apply
there may be no need
wonder if the manuf. instructions says anything on it?

2011

M cebee wrote: »

the rule i was thinking of is in the water heating appliance section so that doesn't apply
there may be no need
wonder if the manuf. instructions says anything on it?

So it would appear that an RCD would not be a requirement in this case (so long as the pump is not supplied from a standard type of socket outlet).

I would very much doubt that the manafacture would require an RCD, but it would be worth checking.

M cebee

wonder are some of these issues related to cabling and joints
-the water travels right up that flex if it gets in and causes leakage-capillary action i think

anyhow if it's not required by manuf. or rules it ain't needed

leeomurchu

I think an rcbo is more of a manufacturers recommendation to reduce possible damage to the pump.

What load is on the pump is it wired/controlled through a contactor or directly to an mcb?

grousedogtom

leeomurchu wrote: »

I think an rcbo is more of a manufacturers recommendation to reduce possible damage to the pump.

What load is on the pump is it wired/controlled through a contactor or directly to an mcb?

its not wired through a contactor ,its wired through a control box which consists of a double pole switch, capacitor and overload determined by the size of the motor being used,the pump and motor in well is switched on and off by a pressure switch.

M cebee

leeomurchu wrote: »

I think an rcbo is more of a manufacturers recommendation to reduce possible damage to the pump.

What load is on the pump is it wired/controlled through a contactor or directly to an mcb?

they're wired back to a starter box with capacitor,overload and switch

i was thinking of installation instructions really as with wastewater treatment which specify fitting/or not of rcd prior to commissioning

leeomurchu

grousedogtom wrote: »

its not wired through a contactor ,its wired through a control box which consists of a double pole switch, capacitor and overload determined by the size of the motor being used,the pump and motor in well is switched on and off by a pressure switch.

Ah right I don't have a lot of experience with single phase pumps I usually work with 3 phase pumps they aren't on a rcd if that's of any use

I'm not sure of the specifics when it comes to well pumps though but I'd have thought it being fed trough a control box there'd be multiple fail safes glass fuses etc that there'd be no need for it to be protected via and rcd.

M cebee

have you checked whether the issue is caused by wiring/joints
or pump motor?
when you've been called back?

M cebee

2011 seems to have it right anyhow

there doesn't seem to be any rule requiring rcd?

imo it's preferable to have rcbo unless the equipment will nuisance trip

grousedogtom

M cebee wrote: »

have you checked whether the issue is caused by wiring/joints
or pump motor?
when you've been called back?

Generally when i am called back i take the control box off the rcd or rcbo and leave it on usually a 10 amp mcb which in turn results in all working fine for years,there is a lead that comes with the motor which is screwed into 3 pins on the motor by a rubber covered connection with a brass thread which ive seen before over time to allow the smallest bit of dampness in( see pic),possibly this is the fault of the rcd to trip.

M cebee

grousedogtom wrote: »

M cebee wrote: »

have you checked whether the issue is caused by wiring/joints
or pump motor?
when you've been called back?

Generally when i am called back i take the control box off the rcd or rcbo and leave it on usually a 10 amp mcb which in turn results in all working fine for years,there is a lead that comes with the motor which is screwed into 3 pins on the motor by a rubber covered connection with a brass thread which ive seen before over time to allow the smallest bit of dampness in( see pic),possibly this is the fault of the rcd to trip.

ya i was looking at the franikon motors on the eps website to see if they have any mention on installation
tbh i wouldn't remove protection if a fault developed without being certain of what's going on

2011

I have installed a few of these over the years and I never used an RCD. I have not had any problems.

I went back to one recently where the pump is used to fill a very large tank. The tank supplies a farm yard, sheds and the farmers home. The idea was to install a level control system on the tank so that the pump duty cycle could be reduced. Apparently turning the pump on & off frequently reduces the pump life. Anyway the level control system is working perfectly with the pump only switching on a few times a day.

The pump is installed without any joins on the cable between the control box and the pump (as the OP described).

M cebee

grousedogtom wrote: »

Generally when i am called back i take the control box off the rcd or rcbo and leave it on usually a 10 amp mcb which in turn results in all working fine for years,there is a lead that comes with the motor which is screwed into 3 pins on the motor by a rubber covered connection with a brass thread which ive seen before over time to allow the smallest bit of dampness in( see pic),possibly this is the fault of the rcd to trip.

http://www.franklin-electric.de/Products/pdfs/manuals/4inch_English.pdf

it mentions in the guide about grease on the motor plug

also gives the minimum IR readings for pump and pump and cable when commisioning

what sort of joint do you use on motor cable and HO7? resin joint?

2011

M cebee wrote: »

what sort of joint do you use on motor cable and HO7? resin joint?

Mine came with the cable connected, no joins.

M cebee

i haven't fitted any but the franklin seems to come with a short motor lead and plug

this will then have to be connected to the HO7 as far as i can tell

serves me right for posting on rules after a few pints-i had already looked at that section a good few times


i can 't see any good reason not to rcbo this equipment.the quoted ir readings for cable and pump motor are high and it seems to me that faults develop over time causing possible undesired leakage current

my general take on domestic equipment and rcd's is that best practice is anything outside generally gets 30ma protection imo-and reci inspectors over the years have said the same thing to me

2011

M cebee wrote: »

i haven't fitted any but the franklin seems to come with a short motor lead and plug

this will then have to be connected to the HO7 as far as i can tell

The last one I installed had a 70m lead made onto it.

i can 't see any good reason not to rcbo this equipment.

Nuisance tripping ?

As the OP Said:

over time an odd motor in the well will cause the rcd to trip and by taking the pump off the rcd and just leaving it on an mcb it will work away fine for years to follow with no problems

the quoted ir readings for cable and pump motor are high and it seems to me that faults develop over time causing possible undesired leakage current

I do not see the issue once the manafactuers instructions are followed.
There is no risk of direct contact.

We have many 3 pahse pumps at work in hazzordous areas and none are protected by RCDs.

M cebee

the plug on the short motor lead connects to the motor-this is where the
manual mentions the grease
the other end is connected to drop flex with joint i guess

M cebee

2011 wrote: »

M cebee wrote: »

i haven't fitted any but the franklin seems to come with a short motor lead and plug

this will then have to be connected to the HO7 as far as i can tell

The last one I installed had a 70m lead made onto it.

i can 't see any good reason not to rcbo this equipment.

Nuisance tripping ?

As the OP Said:

over time an odd motor in the well will cause the rcd to trip and by taking the pump off the rcd and just leaving it on an mcb it will work away fine for years to follow with no problems

the quoted ir readings for cable and pump motor are high and it seems to me that faults develop over time causing possible undesired leakage current

I do not see the issue once the manafactuers instructions are followed.
There is no risk of direct contact.

We have many 3 pahse pumps at work in hazzordous areas and none are protected by RCDs.

there are specific rules re:earthing of fixed equipment with leakage current over 10ma to ensure the integrity of the protective conducter

not saying anything bad will happen worst case here
no rcd
high leakage
loss of protective conducter

maybe nothing i don't know

grousedogtom

what sort of joint do you use on motor cable and HO7? resin joint?[/QUOTE]

Yes the franklin motor comes with a blue flat 4 core type lead which i join to the ho7 using a cellpack resin type joint.

m.j.w

Anytime we are fitting a three phase sump pump in work we are always told to put them on rcds. They never seem to give any bother, dont know why we are told to do it tho when its not in the regs.

M cebee

grousedogtom wrote: »

what sort of joint do you use on motor cable and HO7? resin joint?

Yes the franklin motor comes with a blue flat 4 core type lead which i join to the ho7 using a cellpack resin type joint.[/QUOTE]



do you put the grease on plug?

gilbarry1

ET101 Rule 555.3.2 states:
“A circuit supplying auxiliary equipment associated with water services and water systems (e.g. pumps) shall be protected by an RCD having a rated residual operating current not exceeding 30mA”

Risteard81

gilbarry1 wrote: »

ET101 Rule 555.3.2 states:
“A circuit supplying auxiliary equipment associated with water services and water systems (e.g. pumps) shall be protected by an RCD having a rated residual operating current not exceeding 30mA”

Absolutely. The pump unquestionably requires 30mA RCD protection to comply with the Wiring Rules.