Pond pump installation

[jack2017]

Hi

I'm planning on installing a small pond pump and local electricians seem reluctant to get involved

so I've decided to do the work myself.

My electrical experience is C&G from 35 years ago and my only outdoor experience is 440V 3 phase

The last 30 years have been electronics oriented so while I'm familiar with the issues I'm not

familiar with practice.

Reading the regs I found on .gov it seems I'm allowed to do this work and I've looked around and this

is what I have planned - perhaps someone could throw up red flags if there are any please?

I'm using a small oase under water pump for the pond and will power this by:

Taking a spur from a socket in the back room through the wall and onto a Diall switched fused RCD

connection unit mounted on the outside wall. The house is RCD protected but I felt this may prove

more secure?

From the connection unit run armoured 1.5mm 3 core 10cm underground with a layer of rocks on top and

run a strip of marking tape over that (under the lawn).  The run is about 12 meters long.

The cable to be surfaced alongside the pool and a standard outdoor switched socket mounted on a wooden

block.

I do have questions though as I'm unfamiliar with armoured cable:

1. Is there any requirement to use ducting along the run?

2. Must the armour be flanged and grounded or can I just use it for physical protection as is.

If anyone can see any other issues I would welcome the feedback.

Thanks

jack

 

[Richard-the-Ninth]

What pump you going to use (I know you said Oase, but which one) and what about a UV? or is it just for a fountain?

 

[Lurch]

Reading the regs I found on .gov it seems I'm allowed to do this work

Anyone can do the work, technically it needs notifying though.

Not sure why no-one wants the job though, does seem odd. Maybe they don't want to do any digging, perhaps you could get the cable in (to their spec) and then have someone come and connect and test?

 

[jack2017]

Thanks for the replies

The pump is a submersible aquamax 3000 - it has a UV light and fountain attachment

standard 240v/50   7 watts for the UV and 13w for the pump 20W total.

One electrician I spoke to said he only does indoor work. The others just seemed reluctant.

(That made me a bit nervous - maybe as you say they might not want to dig - but I'd do that anyway)

I'll probably find one just to check over my installation when its done anyway.

My understanding of the regs is that this is not notifiable in England (but would be in Wales)

I'm still wondering about having to ground the armour in the (plastic) box. Does anyone having 

to say about that or anything else. B&Q and wicks don't seem to sell the flanges/parts anyway. 

Also do I have to put an IP66 rated plug on the pump (if such exists) if it is going into a sealed

IP66 rated socket box or can I use any 13A plug?

thanks

jack

 

[Richard-the-Ninth]

The only Oase aqaumax I can find is just a pump, you will also need somewhere to connect a UV to. Please don't get one of those "all in one filter pump UV things" they often fail, and you end up getting separates.

If you have an ip66 rated box why would you need a water-resistant plug? Why not get a water resistant socket? MK make one that you can put in a plug and close the lid*.

You will not get a specific answer to your questions from the regulars as it is a "bone of contention" Or the other way of looking at it is you do what you are told (On this forum) / think is right, and the electrician you get to look says its not right. I for one would bury the cable deeper and earth both ends of the armour.

*I would have a couple, as when you have a pond, you later decide.........oh wouldn't some lights be nice and a.........

 

[apprentice87]

Hi There,

Assuming you want to comply with the regs, the cable wants to be at a depth where it is not "reasonably foreseeable" that it could be damaged. This is generally taken to mean 450mm or 600mm or 1000mm depending on circumstances.

You most DEFINITELY need to earth the armour at the supply end, hardly difficult as you will have to fit a gland anyway to assemble the cable to the box..

john..

 

[jack2017]

Thanks to both.

Yes now I've stopped saying "flange" and realised I meant "gland"  - I can find the info I needed!

Indeed I will ground at both ends.

And I do need to bury it deeper - thanks.

I'm not sure why providing answers is a problem - I thought that was the whole purpose of a forum.

 

[Murdoch]

What is the point of burying the plug and socket.... at some point the pump WILL fail.

 

[Richard-the-Ninth]

What is the point of burying the plug and socket.... at some point the pump WILL fail.

? Bury the plug and socket

 

[rapparee]

? Bury the plug and socket

@Murdoch

He said he was putting the socket on a wooden stake in the garden.

TBH I wouldn't be sure about having one rcd feeding the other.

 

[Murdoch]

oops........

 

[Sidewinder]

Only earth the armour at the supply end please.

 

[Blue Duck]

 FWIW electrical wholesalers sell SWA gland packs for any cable size.

And here's @M107 's Termination Guide .

HTH 

 

[Lurch]

Only earth the armour at the supply end please.

Why?

 

[Sidewinder]

It's safer given the information we have to work with.

What good is earthing it load end only, and how are you going to accomplish that & comply with BS7671?

 

[Lurch]

What good is earthing it load end only, and how are you going to accomplish that & comply with BS7671?

Well exactly, I never said do that though. Nothing wrong with earthing it at both ends.

 

[Sidewinder]

Well exactly, I never said do that though. Nothing wrong with earthing it at both ends.

Just interested in how you are going to accomplish that...

 

[jack2017]

Sidewinder does bring up a good point. One I should have asked myself.

Whilst I'm unfamiliar with common practice in the electricians/power  world - in

my experience in the world of electronics this is a recurrent issue.

(More so with high frequency circuit board design but others also)

To give some examples - I have personally seen a computer network

(several actually) ravaged by random corruption.

I have also personally fixed a wildly gyrating factory robot arm.

In both cases the issue was caused by the installation engineer

grounding both ends of an RS232 cable. (I am going back

a few years)

This set up a ground current loop that interfered sparodically with

the signal. As we all know - current returns via the path of

least resistance (or least impedance at high frequency)

and with cable runs this can mean an induced or other  ground circuit.

If given a choice I would only connect at the load end however

electricians have all said  both ends for the type of run I'm doing

as has been suggested here. As I am keen to comply with

regulations and safety and reliability:-

The choice is:

1. Both ends

2. Load end

3. Supply end

If someone has a specific reliable link for either regulation

or common practice in this respect that would be very helpful.

Do the 17th edition people here cover this at all in their training?

thanks

jack

 

[steptoe]

Ok, the cable can only be earthed at supply end, 

That is where you are getting the earth from,

You can, if you wish connect it at load end as well,

But, with current info, I'd tend to agree with sidewinder and say supply end only,

NEVER ever, only connect at load end, it almost doubles the path of earth under an armour fault (simplistic view)

 

[Lurch]

Just interested in how you are going to accomplish that...

I think we're at cross purposes again. I (now) assume you meant drive a rod at the load end and bond that, I was just referring to connecting/bonding the armour at both ends.