Shower Bonding

[KhaoYai]

Question for someone either qualified or with serious electrical knowledge.

 

I recently installed a full hot water system in my home - the heater is an air source heat pump. I presume that there is a heating element somewhere that heats the 200l storage tank. The heater is earthed and I intend wiring an additional earth rod to it. However, I stupidly ommitted to bond the metal parts of the showers and kitchen sink to the house's earth circuit.

 

I'm faced with removing tiles in order to correct this but is their an alternative? The heater unit is currently plugged in to a normal socket but it would not be difficult to wire it in to a dedicated circuit which, if my thinking is correct, would allow the fitment of an RCBO.  Would that be adequate?  I suspect that the only safe way is to both sort the earth bonding and power the unit via an RCBO.

 

Although it means removing tiles which I really don't want to do, its not that bad because the bathrooms/showers are back to back and the tiles are very large. The last 150mm of the supply is in copper and I should be able to get to that on both showers by removing the tiles on just one side.

[CharlieH]

Moving to Electrical forum for focused responses.

[Moonlover]

20 minutes ago, KhaoYai said:

I presume that there is a heating element somewhere that heats the 200l storage tank.

Are you serious? You mean you have just installed an air source heat pump and you don't know how they work?

 

'Air source heat pumps absorb heat from the outside air. This heat can then be used to heat radiators, underfloor heating systems, or warm air convectors and hot water in your home. An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside'.

 

There no heating element involved. Think air conditioning in reverse. That might just change your view regarding earth bonding.

 

I do, however commend you on your choice of this eco-friendly water heating system.

[dimitriv]

1 hour ago, KhaoYai said:

However, I stupidly ommitted to bond the metal parts of the showers and kitchen sink to the house's earth circuit.

 

In my condo these things are also not earthed. At east not visible. Is this really needed ?  The metal parts of the shower feels like plastic. You only need to earth them if they are metal and connected with steel pipes. And if you want to do that I am sure you can do that by attaching earth to the pipes somewhere else. 

 

 

[KhaoYai]

1 hour ago, Moonlover said:

Are you serious? You mean you have just installed an air source heat pump and you don't know how they work?

Is there any need for you to be so pompous? It would be a fair guess that you drive an automatic car - do you know how an autobox works? I'm a mechanic, I do - because its my business to know. I also watch TV but I have no idea how a TV works.

 

I chose this form of water heater on recommendation from the seller who is a friend and visited 2 users - one who runs a restaurant running the same type for 4 years and reckons it cut his electric bills by 2/3. Some people don't see the point in having hot water in Thailand some do. Some are happy with electric showers - some are not. I wanted constant hot water at high pressure, available at all points with low electricity consumption. So far, for my needs, this unit is certainly giving me what I want.

 

Although I undertstand the heat source principle, I don't know exactly how they work, I don't need to, I just know that in comparison to other forms of water heater, they provide reliable hot water at a reasonable price. However, I'm guessing there must be some form of supplementary heating as the unit will heat water up to 60 degrees (and it does). The outside temperature is around 30 - 35 daytime. In any case, if there is any risk of electricity coming into contact with water, I want to be as safe as possible.

 

It may well be that this unit doesn't need earth bonding but I'd like to have that confirmed by an electrician.  To that end, the unit is very similar, if not identical to this:

 

https://cripton.com.sg/products/air-source-heat-pump/domestic/#.XcmU9dXgrIU

[KhaoYai]

1 hour ago, dimitriv said:

In my condo these things are also not earthed. At east not visible. Is this really needed ?  The metal parts of the shower feels like plastic. You only need to earth them if they are metal and connected with steel pipes. And if you want to do that I am sure you can do that by attaching earth to the pipes somewhere else. 

I fitted the heater, the pipework and the showers, I can assure you that the showers are metal, mainly chromed brass in fact - I imported them from the UK as I couldn't find decent quality thermostatic units at the right price in Thailand. Only the last 150mm of pipe is metal - copper in fact. The rest of the pipework is standard PVC for the cold and PPR for the hot.  It wouldn't matter if all the pipework was plastic - a leak of electricity in the 'wet' side of the unit could be transfered through the water to anyone touching the metal parts of the shower and thereby acting as an earth.  I don't particularly want to be an earth ????. There is absolutely no way of getting to the metal parts without removing at least one tile, probably 2 - unless I want hideous earth cable or trunking running down the walls of my newly built bathrooms - no way.

 

Incidentally, for the benefit of anyone thinking of using the PPR plastic hot water pipe system: If you are using it on a new build or the system you are planning is in the open, that should be fine. However, if you are retro-fitting or installing pipes in hard to get to places - import a push fit system or use copper. 

 

Much of my pipework is in a suspended ceiling. The PPR system uses an electrically heated arm with varying sizes of interchangeable spigots fitted to it. Basically, you push the pipe over one side of the spigot, and the joint over the other. Hold them there for a few seconds then pull them off and push them together - its almost like plastic welding. You could do with 3 hands, one to hold the arm, one for the pipe and one for the joint.  On the floor, you can just about manage it or get someone else to hold the arm for you.  Working in a suspended ceiling from a ladder is a completely different thing - I had burns all over my arms, I wouldn't recommend it.

[Crossy]

 

5 hours ago, KhaoYai said:

a leak of electricity in the 'wet' side of the unit could be transfered through the water to anyone touching the metal parts of the shower and thereby acting as an earth.

 

Unless there's a metallic (copper) path from anything electrical to the shower unit / sink etc. don't worry. Water, even relatively impure (tap) water is not a good enough conductor to cause you any issues.

 

I assume your heat pump is protected by an RCD, if so you have absolutely zero risk (if not you should install one).

 

EDIT On re-reading the OP I see the heat pump is plugged into a regular outlet. Nothing to stop you adding an RCBO to that circuit or adding a whole-house RCBO. You certainly should have some form of earth leakage protection on anything in damp areas or outside.

 

If you're worried check for a resistance between the metallic part of your shower and the casework of the heat pump. If you read less than a few 10s of k then you should think about bonding.

 

[sometimewoodworker]

4 hours ago, KhaoYai said:

its almost like plastic welding.

It’s not almost like plastic welding, it is plastic welding. Just cut open a joint. Unlike PVC joints which are reversible 

[Moonlover]

6 hours ago, KhaoYai said:

Is there any need for you to be so pompous? It would be a fair guess that you drive an automatic car - do you know how an autobox works? I'm a mechanic, I do - because its my business to know. I also watch TV but I have no idea how a TV works.

 

I chose this form of water heater on recommendation from the seller who is a friend and visited 2 users - one who runs a restaurant running the same type for 4 years and reckons it cut his electric bills by 2/3. Some people don't see the point in having hot water in Thailand some do. Some are happy with electric showers - some are not. I wanted constant hot water at high pressure, available at all points with low electricity consumption. So far, for my needs, this unit is certainly giving me what I want.

 

Although I undertstand the heat source principle, I don't know exactly how they work, I don't need to, I just know that in comparison to other forms of water heater, they provide reliable hot water at a reasonable price. However, I'm guessing there must be some form of supplementary heating as the unit will heat water up to 60 degrees (and it does). The outside temperature is around 30 - 35 daytime. In any case, if there is any risk of electricity coming into contact with water, I want to be as safe as possible.

 

It may well be that this unit doesn't need earth bonding but I'd like to have that confirmed by an electrician.  To that end, the unit is very similar, if not identical to this:

 

https://cripton.com.sg/products/air-source-heat-pump/domestic/#.XcmU9dXgrIU

Oh dear I did touch a nerve. My apologies. But for the record I have always driven and much prefer a manual shift over the lazy drivers auto system. ????

As for your actual inquiry, I wouldn't think that earth bonding will be a big issue for you. I think @Crossy has more experience than me as I was electronics rather than the 'heavy stuff' but his looks sound to me. 

 

Once again I I congratulate you on you wise choice of water heating.

 

Have a nice day.

[steven100]

and I thought the topic was about sex in the bathroom ...

[Crossy]

To add to my earlier post.

 

Little stand-alone RCBOs complete with small plastic boxes are readily available for 400 Baht or so. You could easily put one between the heat-pump and the outlet feeding it.

 

They look something like this, note the "Test" button.

 

  

[Tayaout]

8 hours ago, dimitriv said:

 

In my condo these things are also not earthed. At east not visible. Is this really needed ?  The metal parts of the shower feels like plastic. You only need to earth them if they are metal and connected with steel pipes. And if you want to do that I am sure you can do that by attaching earth to the pipes somewhere else. 

 

 

Oh yes they have to be earthed. If there is an issue you will be the one "earthing" the circuit. 

 

Edit: I think your are not even talking about this kind of shower.

 

[steve187]

17 minutes ago, Crossy said:

To add to my earlier post.

 

Little stand-alone RCBOs complete with small plastic boxes are readily available for 400 Baht or so. You could easily put one between the heat-pump and the outlet feeding it.

 

They look something like this, note the "Test" button.

 

  

crossy could you put one of these between the CU and a shower room heater

[Crossy]

Just now, steve187 said:

crossy could you put one of these between the CU and a shower room heater

 

Yup. I've updated the photo since your quote to include the page from the Haco catalog that includes the box too.

 

The installers often use a "Safety Breaker" which is the same form-factor but doesn't include earth-leakage protection. It's a simple swap out job. Do ensure that you have the Line and Load connections the right way round, it will work just fine until you press the Test button, then the magic smoke will come out and it stops being an RCBO. Ask me how I know  

[steve187]

6 hours ago, Crossy said:

 

Yup. I've updated the photo since your quote to include the page from the Haco catalog that includes the box too.

 

The installers often use a "Safety Breaker" which is the same form-factor but doesn't include earth-leakage protection. It's a simple swap out job. Do ensure that you have the Line and Load connections the right way round, it will work just fine until you press the Test button, then the magic smoke will come out and it stops being an RCBO. Ask me how I know  

thanks

[KhaoYai]

11 hours ago, Crossy said:

EDIT On re-reading the OP I see the heat pump is plugged into a regular outlet. Nothing to stop you adding an RCBO to that circuit or adding a whole-house RCBO. You certainly should have some form of earth leakage protection on anything in damp areas or outside.

Thanks for your input Crossy, my worries are a result of UK wiring regulations where everything has to be bonded - maybe a bit OTT but what price is safety?

 

I was hoping an RCBO would be sufficient. The house is relatively modern so the Schneider consumer unit uses breakers and an RCD. However if I'm not going to install any bonding to the showers I'd feel safer with an RCBO.  The Air Source pump was connected to a socket in the laundry room on a temporary basis - I always intended giving it a seperate supply. That is actually quite easy to do as I have a more or less spare circuit.

 

The bathrooms previously had electric showers installed which were fed from a dedicated 'heavy circuit'. When the showers were removed I pulled the wiring up into the loft.  As this circuit employs heavier (4mm from memory) wiring I used it to provide power to an electric oven point in the kitchen and currently, that's the only item using that circuit. There were 2 showers so 2 lots of wiring - both out of the same breaker. One now goes to the oven socket, the other is spare (still taped up in the loft. I presume it will be OK to use this spare wire to power the Heat Pump through an RCBO. In addition, would there be any point in giving that RCBO its own earth rod? The cost of doing that is negible.

[Crossy]

Actually the more recent editions of BS 7671 have reduced the need for bonding, the shower and sink you describe likely wouldn't need it now.

 

If you already have a ground at the heat-pump no need for another although it wouldn't hurt. If the beast is running happily from the outlet circuit (unless it's got all the kitchen on there too) I'd leave it be and slip one of those Haco RCBOs in the plug lead.

 

Whatever you do, do add an RCBO somewhere.

[KhaoYai]

17 minutes ago, Crossy said:

f you already have a ground at the heat-pump no need for another although it wouldn't hurt..................

Cheers.

[VocalNeal]

I thought shower bonding is something one does before.... Oh wait this is the electrical forum. 555