Oh deep Joy, New DB and a tripping problem. I can't find anything specific on Google to help me and it's the worst kind of tripping problem; It's a poo pump made by a company called ABS. it is in an annexe attached to a bigger house, separate DB feeds from a Henley block with the house on a Zs installed hager 100A fused switch.

It's been a real head-scratching day with other issues and the final circuit into a new DB was the pump. I was getting 11.3 volts down the pump cables even with the board switched off and eventually found an unexplained neutral connected through the pump SFCU on the feed side, and onward to the outside lights, which are powered from the main house. I couldn't see its purpose so I chopped it off and cleared the circuit to all test results perfect. the outside lights are working fine so I've no idea what that was all about. Well, except that the house is fully RCD protected and the annexe wasn't???

It is 0.8KW and they have a voltage of 245 (normal round here). It was on an old Dorman Smith 5A this morning so I put it on a 6A, then 10A and it took out the MCB (not the RCD). On a 16A it holds for two or three minutes and then takes out the RCD (not the MCB).

Had the cover off the pit and it is empty. But it doesn't smell like roses.

Because this annexe was always going to be a problem I had allowed for an emergency non-RCD space so I ended up having to put it in there and it is holding ok.

But through the RCD the pump unit buzzed considerably, it does not buzz without the RCD.

The client says it is five years' old but I doubt that very much. I've been looking after this house for 10 years and it has always been there. Looks more like 15 or 20 years old. Big black box with an orange logo and a steel, embossed data label.

I've got to sort it of course. If you have any experience with these units I'd be interested in any pointers. Of course they need a new pump but the old mantra 'It was working before you came round' applies. Oh bum.

Zs

Zs,

Firstly be real careful anywhere near the "chamber". The gases that can be present could get to you well before you realise and the next thing you won't know is you'll be down there floating in the p.. and unable to do anything about it. Not a nice way to end your time on the planet.

Can't think why the RCD would make the pump buzz ??

What triggers the pump, is it on floats and a control box or is there a float on the pump.

For my sins, I've got quite a lot of experience of being in s..t, it sort of goes with the customer base I keep.

Stu

If the pump is taking out the MCB and the fixed wiring and windings are testing OK - then the pump impeller is stuck full of CR*P. Sounds like it has all dried out and gone as hard as cement.

I too have a lot (relative to all but those who work in the industry) of waste water sewage pumps as I spent a year doing some of the automation upgrading for the london ring main and Slough, Reading and Dartford treatment plants, LOVERLY STUFF!! Three stand alone sewerage flood pump plants too.

Seriously though - I really did enjoy control pannels and the automation side of electrics. You soon get aclimatised to the wiff. As long as you shower before saying hello to the wife - all is hunky dory.

ABS= Allan Bradely?

Beware too - there's a lot of disease on the pumps and impellers and getting cut is a bad plan. Leptosporosis (Weilds disease) is another common one in those areas too.

Thick/sturdy gloves are a good plan.

Would that be a smell something like ammonia that practically throws you backwards and makes your eyes water? If so, then I now qualify for ticking that box on the CV. Even listerine won't budge it. Thank you very much for the heads-up.

If it were floats I would see them in the pit wouldn't I? What I can see is right down to the ground and a Y shape of grey plastic pipe about four inches in diameter and no floats. There is evidence of what I shall politely call debris though and clear evidence of a level the pit fills to. I've a notion the pipes are just sharing the route and nothing to do with the pump. I have installed one of these so I'm familiar with what floats look like hanging on their cable and I don't see any.

I spoke to Gary the pump man who advised the switching surge might be quite high, hence gradually upgrading the MCB. He's at a a beach bar in Spain so credit to him for taking my call. However, he's not an electrician and said he couldn't help with today's issue. He just unblocks the things.

Meanwhile, I have poo to pump. Last resort is to leave it without RCD and note it but something is wrong which ideally should be sorted and I'd rather not skirt around it.

Thanks Stu,

Zs

and Thanks Tatty too.

Sounds like the winding has gone down on the pump. A jammed impeller would take out the MCB but probably not the RCD. With a larger MCB the winding is getting enough current for enough time to heat up and short to earth. Clamp the line and neutral to the pump with your earth leakage clamp meter and see what you get? Also clamp the line to see how much current the pump is pulling?

Wash hands before eating sarnies!

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/

Therin may lie the problem

(Sorry)

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S George
http://www.state-it.com

Could be a dodgy flex. When the motor starts the pump tends to kick and twist which can lead to, if it has threaded pipe fitting to the pump unscrewing it's self. Also if HO type flex the cores can twist inside and not be that obvious outside.

Generally the motor - internal error or external error:

If nothing's moving then the winding may be up the duff.

If the winding's OK then the stuff it's pumping is not moving.

If the stuff is not moving then it's a blockage down the line or the blades are jammed.

Think yourself lucky your looking at a single domestic experience as opposed to an off-grid multi-occupancy sewage experience!

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S George
http://www.state-it.com

ha stateit, and it's in Amersham Daarlings so at least it is posh poo

I've been on google. Cor what I now know about pumps and floats and approved installers. I've only found one blog complaint about tripping. I'm joining one after this and i'm going to call myself the Honey Man.

I did clamp it JP but everything was normal. It tripped at 26mA of leakage after a steady rise, on the 16A breaker so I reckon you are quite right. Am tempted to kick it.

What that last paragraph really means is theat I did spend 40 minutes extending cores all over the place so that I could get the clamp meter round them, and then spend 10 minutes explaining to the returning tenants who I am and why their lounge was trashed with tools etc. and then ran the tests. . . you know the kind of thing.

I'm all over it, but only back there on Friday afternoon. I will keep you in the loop. In the meantime I have had a bath and everything and it is not even my birthday. Huge thanks pals.

Zs

Amersham I know well, s**t is the great leveller. What was the IR reading on the pump installation and the motor in particular?. I suspect that the problem is due to a faulty seal.

Regards

Zs

is there a pump control panel?
does the pump have a float switch?
How many cores come from the pump flex.

if the chamber is empty where is the pump in relation to this? please dont run the pump with no 'liquid matter'

Ive not worked on small pumps like these, but you get thermistor protection, seal leak devices etc assuming that it has a control panel.

ABS pumps are good but easier to find would be flygt pumps, if you need to swap it over.also have a better serice dept.

get the details from the pump data plate
tong test the supply to see what its pulling.
to be honest we never used rcds on ours due to other protection devices, hard wire it in and engineer the rcd out.
make sure you dont run it dry, ie if you pull it out, pop it in a bucket of bleachy water to run., cleans it at the same time, could be a blockage! of course the impellar could be ragged up.

remember rubber gloves at all times, sometimes its easier to put on 2 pairs!
good luck

And remember not to lower a live pump with a float switch into a pit whilst holding onto the nice 6" discharge hose ready to connect. I learnt the hard way after a face-full!

-------------------------
Regard
Richard (Dick)

www.rllewellyn.co.uk

Very nearly done that with pig slurry recently, not a pleasant experience !


Stu

What size is the discharge line Zs - from your description, I suspect this is a 2" discharge and you have a standard submersible pump probably with cutter tips on the impeller - so mind fingers.

At that sort of leakage you either have a winding going down or the seals have failed (although ABS are essentially a brand of Sulzer pumps - and they are pretty bomb proof)

I can't quite work out how you've been able to run the pump if the chamber is empty - lifting the float switch perhaps - and i think those pumps have integral thermal overload protection, so if running dry it's going to get hot, quickly - which may or may not account for "buzzing"

If you can get it out easily, shove it in a dustbin full of water with plenty jeyes fluid - that will usualy give you enough run time to see sensibly what's happening with current demand and leakage.

Personally, I'd go back to your client and tell him to get the pump checked over/serviced - both your experience with the MCB and RCD suggest that the pump is failing - rectifying it is not something you want to be taking on if you can avoid it

Take Dettol with you - and don't be scared of using it, not exactly Channel I accept - but the pathogens swarming around in human effluent sumps don't bear thinking about - and if you feel like your getting the 'flu anytime soon, get to the MedicO soonest - and tell them you've been close to sewage

Regards

OMS

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Failure is always an option

This sounds single-phase, so over the noise of the pump i'm going to shout "capacitor".

If it's a small chamber it could be that the few minutes it's run are enough to present Zs with an empty chamber, some of them shift it pretty quick.

I'd agree with OMS regarding getting someone else to do the pump, depending how big it is doing something with it once it's on the surface can be a challenge. We've had a few taken into our local motor/pump specialists but generally in the side locker of a sludge tanker or in a trailer. It's certainly not something you want in the back of the van or worse still on the passenger seat

If i'm in the sh!t I tend to wear a pair of nitrile gloves under a pair of decent long pvc/rubber gloves, at least that way you can take the outer ones off whilst still having some protection and then in best medic style take the inner pair off turning them inside out as they come off. funny thing is I only worry about gloves if it's human. Pigs & Chickens seems to wash off easier and tastes better

Stu

Yuk.

I did not see the pump running, I could just hear it while the unit was between trips. It is on an auto setting and you are probably right that it had emptied before I took the cover off the pit.

I am back there tomorrow afternoon and will look into the chamber as soon as I get there. then I'll flush the toilets and run some taps and see what happens.

When I left it was on, not running though, and holding out on the 16A type B MCB without an RCD. I asked the tenant to call me if the neon on the SFCU went off and all has been quiet.

I'll take some more measurements, I'm thinking type C not protected by RCD. But for all these years it has been on a standard 5A dorman Smith breaker and there was no sign of any overheating on the 1.5mm cable, nor any on the breaker. Mind you, I did just say Dorman Smith..do they ever blow??

Yes, I plan on leaving the maintenance of the actual unit to Gary when he gets back. I'm hoping it is working and I won't have to do anything in the meantime. Gloves at the ready.

It is just so unfortunate because I'm taking the rap for it of course.

I'll let you know, it might be a long day though cos I also have a neutral to earth fault on the lighting to find and I'm going to have to break it into chunks failing finding it visually and some finishing off to do on the DB change, which is currently, er, somewhat adapted.

Thank you again,
Zs

I would expect to use a type D or at least a C on a pump to handle the start up current which is about 7 times full load current for a DOL started motor. That said it does sound more like a ceased impeller or
as else someone mentioned the capacitor starter which has the potential to cause the noise. The capacitor provides the phase shift to allow the motor to start and run so if this was faulty the motor would not start and would be drawing way above full load current which would trip the MCB after time and also account for the noise.

Also ABS are a German pump control company and not to be confused with AB Allen Bradley. I would also be wary of connecting the control unit via a standard RCD.

Good luck, it sounds like a nasty job.

Edited: 31 August 2012 at 04:54 AM by alamatec

Alamatec,

It doesnt sound like a nasty job, its only a small pump in a small chamber with a little bit of sewerage
However doesnt mean you shouldnt be careful, dont go climbing in the empty pit, confined spaces and all that.
Watch when you first lift lids,for collected gases etc, leave it to vent for 10 minutes prior to sticking your head down the hole!

Let's start at the very beginning, a very good place to start.

What is the I.R. of the installation and the pump motor? It's not in the qualifications, it's in the application of them.

Regards