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BANGKOK 17 June 2019 14:19
cheeryble

Replace water heater

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Handyman has said the dial is not working and either v hot or cold.

IT's 4.5kw.

Probably time for a replacement.

Do you guys think the incoming cable looks like larger than 2.5mm2? Maybe 4? 

 

If wife orders a new heater from say Powerbuy or the like I'm guessing they won't fit for free as it's quite a cheap device. Any ideas of fitting price?

 

Should a new heater have any sort of extra protection like RCD or are they self protected and it will run happily like the old one has for a decade or two?

Fuse box is just a basic one with trip switches.

 

Thanks....

IMG_7332.thumb.jpg.e6738adaf463d3551fb3d61b2ce1d84b.jpg

 

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The cable should be marked, it's very difficult to tell from photos.

 

Up to 4.5kW (20.5A) should be fine on 2.5mm2 and a 20A breaker.

 

All modern heaters have a built in RCD/RCBO for added safety, but they all require a ground too.

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1 minute ago, Crossy said:

The cable should be marked, it's very difficult to tell from photos.

 

Up to 4.5kW (20.5A) should be fine on 2.5mm2 and a 20A breaker.

I knew you'd be there Crossy!

SO basically just check the breaker and swap the heater eh?

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A like-for-like swap should just work. But please do verify there's a ground at the heater.

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Yeah, unless that is 3-core cable (unlikely) or ground is going out through the back wall, it appears you do not have ground.

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It’s not so far to the fuse box are they normally earthed here so the cable could be changed for TW&E?

Just across boarded ceiling and thru wall

 

Sent from my iPad using Thaivisa Connect

 

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Posted (edited)
38 minutes ago, cheeryble said:

It’s not so far to the fuse box are they normally earthed here so the cable could be changed for TW&E?

Just across boarded ceiling and thru wall

 

Sent from my iPad using Thaivisa Connect

 

First take off the cover to see what's there now - don't go poking around unless you have power off.  Assuming you don't have ground you could replace with 3-core (if you can find it sold by the meter) or just run another wire from your box.  Ty-wrap it under the current one and should look OK.  Your "fuse box" does have proper ground, yah?

Edited by bankruatsteve
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Good morning to my marvellous experts.

 

Looks like it needs changing.

I didn't have time to work everything out but have a couple of useful pics inside heater and consumer unit.

First, the supply cable to the heater definitely looks above 2.5mm2 (although I understand 2.5 is adequate for 4.5kw anyway)

Second, there's no earth in the cable to heater and although I see a green wire coming out of the connector block top left inside the heater I don't see an earth coming into it from the top, so the can't be a separate earth coming from the wall.

A couple of possibilities crossed my mind.

1. THere's a pipe column just a metre or so from the heater, though whether there's anythng metal to connect an earth to .....I think the pipes are plastic.

2. The heater supply cable comes across above the ceiling a few metres from the pictured consumer unit which is on the other side of the wall. But all the wires are black or grey, so I'm thinking no earth? (Cant see the heater cable exiting the CU it must be tucked away.

What I'm wondering is whether instead of an earth using an RCBO device.

I first thought of a new RCBO consumer unit.

I then wondered if a RCBO switch unit could make all the circuits from the existing CU safe.

Either of the last two would be a bonus and a bit of an electrical upgrade.

 

Thoughts welcome.

 

IMG_7348.thumb.JPG.863f51b288bf435cb5b27ead3fcbeaa0.JPG

IMG_7349.thumb.JPG.a10ab692c84748fccb646b3c7d8387fa.JPG

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Posted (edited)

Oh dear.  Well, you don't have earth/ground.  I don't even see an earth bar in the box.  A main RCBO would be "good" but if safety is a concern, you really need proper earth to your shower unit and the receptacles.  Again, the shower units will come with RCD protection but if something goes wrong, you really do not want to be zapped with 30ma.  Maybe that won't kill you, but likely to cause injury.  Earth/ground connection to device would prevent that.  One thing you could do with the shower is connect the ground wire from the unit to a wire that is connected to the steel in your structure - should make a good ground.

 

Is that round thing a light?  If nothing else get someone to put a crimp terminal on the wires.  The way those strands are frayed out is a good recipe for arcing (fire).

Edited by bankruatsteve
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4 minutes ago, bankruatsteve said:

Is that round thing a light?  If nothing else get someone to put a crimp terminal on the wires.  The way those strands are frayed out is a good recipe for arcing (fire).

Its a bottle fuse.

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Posted (edited)
45 minutes ago, cheeryble said:

IMG_7348.thumb.JPG.863f51b288bf435cb5b27ead3fcbeaa0.JPG

 

Looks like the cable termination has been cooking.

 

cooking.jpg.bc3e33c2e862e116da186f33c37417a2.jpg

Edited by Fruit Trader
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Thanks to all!

 

I did notice the wire connection to the bottle fuse (I figured it was some kinda palaeolithic fuse!) ain't great, and also the charring of the white wire at the terminal block in the heater........the handyman had said it's the dial/rheostat thingy so maybe I was fixated on that but who knows?

 

I also notice some filled screw holes next to the heater so it's been replaced at some point.

 

The heater has been there quite a few years so I'd be kinda surprised that the white wire to the block should get looser so maybe tightening it may not be a cure.

 

Bankruatsteve i do notice from the photo in the OP the left button says RESET so presume it's protected?

In fact I just learned the right button says TEST. The two little lights to the left the bottom one says ELCB and comes on green with the power from a switch near the door. The top light POWER could come on red when the heater was initiated by water flow I believe.

The fact there;s a heater switch near the door means if it was all changed to an earth system rather than just RCBO or whatever there'd have to be some reconnecting above the ceiling or wherever that headed off to the switch. Presumably the switch doesn't need an earth its;f it would be like a light switch power in and out.

 

One thing i don't really get is why an earth is needed if one uses RCBO at the fuse box. Isn't the RCBO fully protective?

Thing is it would be great if an RCBO/s could also protect all the sockets and lights ......and presumably aircon......it would be great. But i'm guessing the cables to sockets etc are just two core like in most of Thailand so to earth them properly would essentially mean rewiring the whole place which has been running happily for a decades.

 

I guess a useful step would be for wife to ask handyman if there's a good earth within reach from the fusebox also.

 

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OK.  Sounds like your heater does have RCD protection then.  (Did you press the TEST and then did it RESET?)  The unit's power light comes on when you on the switch?  If so, that white neutral is probably still making contact but I would check it anyway.

 

An RCD (RCBO, etc) will trip on a fault current of 30ma.  A ground wire will carry fault of any size to the ground.  In absence of a ground wire, the fault goes through YOU.  Believe me, you do not want a 30ma fault to go through you.  it will knock you on your ass and, in a slippery shower, that would also result in injury.

 

Again, a decent ground can be the steel in your structure - make sure good contact like with a screw.

 

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Posted (edited)
1 hour ago, bankruatsteve said:

OK.  Sounds like your heater does have RCD protection then.  (Did you press the TEST and then did it RESET?)  The unit's power light comes on when you on the switch?  If so, that white neutral is probably still making contact but I would check it anyway.

 

An RCD (RCBO, etc) will trip on a fault current of 30ma.  A ground wire will carry fault of any size to the ground.  In absence of a ground wire, the fault goes through YOU.  Believe me, you do not want a 30ma fault to go through you.  it will knock you on your ass and, in a slippery shower, that would also result in injury.

 

Again, a decent ground can be the steel in your structure - make sure good contact like with a screw.

 

Been doing a bit of research and yes it seems to me an RCBO or RCD is specifically designed to trip before a leak is life threatening.......but certainly earth would be good in the shower heater.

I'm thinking Maybe a combo job could be done where.......if a ground can be identified close to CU or WH......the shower heater could be earthed, and the rest of the residence could be protected by RCBO at the CU alone. 

 

I also wonder if someone knows an electrician in CM fully competent at this sort of stuff......possibly a rare bird but sure there will be some. I wonder if the installation guys from Siam TV, Powerbuy etc are up to snuff and, bearing in mind they may be using subbies,would do the CU RCBOs too

 

Edited by cheeryble

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