9.5 kw shower

[balrog]

Hi folks!

I have just joined the forum mid - project, and wondered if anyone might be able to comment on a couple questions I have regarding the 9.5 Kw shower I am fitting.

I notice that the bathroom is earth bonded with 2.5 mm earth wire. Is this cable heavy enough or should I replace it with 4mm?

I have run 10mm cable to the shower and want to join it mid run. I am being told that I can use a 30 amp junction box to connect this cable, is this junction box big enough?

If the 30 amp junction box is sufficient to join the 10mm cable, can I also connect the earth bonding to the earth terminal in the junction box to provided a route back to earth, and should I include the gas pipe to the central heating boiler in this earth bond,

Thank you all kindly for reading.

Best Wishes

Bob

 

[breezer]

its always best to have no joints, i would change the whole cable.

if you really must join it, then the 30A Junction box is too small

and no you cant

and 6mm -10mm better, not 2.5

 

[dingbat]

Supplementary bonding is fine in 2.5 sq mm as long as mechanical protection is provided. If not, then 4 sq mm is what the regs call for.

Make sure you know the difference between 'earthing' and 'bonding'.

 

[ban-all-sheds]

I am being told that I can use a 30 amp junction box to connect this cable, is this junction box big enough?

Dunno who told you that, but next time you see him, ask if he can do simple arithmetic, like 9500/230, hopefully getting the answer 41.3. If he can, ask him why he told you that a 30A JB would be OK for a 41.3A load.

and no you cant

Breezer - which bit of the question was this an answer to?

 

[securespark]

If the 30 amp junction box is sufficient to join the 10mm cable, can I also connect the earth bonding to the earth terminal in the junction box to provided a route back to earth, and should I include the gas pipe to the central heating boiler in this earth bond

Maybe it was this bit Ban, but not sure. I think he's been on his namesakes again!!

 

[balrog]

Hi folks!

Thank you all for your advice on this one. It was a qualified electrician who told me to use a 30 amp junction box, I did not think it was right!

I have got to join the cable but now have a 100 amp connector block, and thank you for the word on earthing as opposed to bonding, I did know the difference!

again,

Thank you very much


Bob

 

[AdamW]

What do you mean by "100A connector block"? Chock-block? The plastic bar with screw-down terminals in it?

Cable joins MUST be accessible. So you CAN'T join the two cables and then bury the join in plaster (with the exception of crimped joins). You must be able to easily get to this block and check the screws are tight, for instance. So you could join them in a wall box covered with a blanking plate, for instance (provided you can physically get the cables and connector block in there).

Personally, I would ditch the joining effort and buy a new piece of 10mm.

 

[ban-all-sheds]

If the 30 amp junction box is sufficient to join the 10mm cable, can I also connect the earth bonding to the earth terminal in the junction box to provided a route back to earth, and should I include the gas pipe to the central heating boiler in this earth bond,

Whilst we wait for Breezer to sober up....

Not only can you connect your supplementary bonding to the cpc of the shower circuit, you must do so.

As for the boiler - if it's in the bathroom, and the gas pipe by which it is fed is metal, then this pipe should be supplementary bonded just like the water pipes. If it's not in the bathroom then there won't be any supplementary bonding to connect it to.....

 

[balrog]

My 'connector block' is a 100 amp, 5 way, 2 pole service connector. It will be readily accesible when in place.

The boiler is not in the bathroom but is passed by the main earth bond cable on it's way back to the consumer unit. I wanted to join the gas pipe into the main earth bond one piece cable.

I understand that the water pipe to the shower should be connected to the main earth point within the shower unit via an earth clamp and the suplementary earth bonding.

Thank you all again for reading,

Bob

 

[AdamW]

I believe that is what is often referred to as a "Henley Block". As it is usually used for joining meter tails (hence the 100A rating) and you are having it accessible, then I would think it is perfectly fine for this. Some might even call it overkill!

(I am not a spark, but the connector block sounds OK to me)

 

[ban-all-sheds]

The boiler is not in the bathroom but is passed by the main earth bond cable on it's way back to the consumer unit. I wanted to join the gas pipe into the main earth bond one piece cable.

On its way back from where? Main equipotential bonding conductors run from where the gas & water service pipes enter the property to the main earthing terminal. Not to the CU:

And how far is it from where the service pipes enter to the MET?

 

[balrog]

Hi folks,

I have now linked all the metal appliances in the bathroom together on an unbroken 4mm earth wire, directly linked back to the main earth block where the electricity supply enters the house. I propose to do the same with the cold water supply pipe to the shower, which cannot be accessed from within the bathroom. There is a 2.5 mm supplemental earth bond between the pipes on the bathroom and the water pipe to the shower.

Any problems here?

The shower is 9.5 kw, I have been told that 40 amp RCCB is adequate. Should this not be 42 amp? If I use the 40 amp RCCB, will it be adequate?

Many Thanks

Bob

 

[securespark]

Ban

MK put earth terms in their CU's labelled "BOND" so people must use them for bonding.

 

[ban-all-sheds]

I have now linked all the metal appliances in the bathroom together on an unbroken 4mm earth wire, directly linked back to the main earth block where the electricity supply enters the house. I propose to do the same with the cold water supply pipe to the shower, which cannot be accessed from within the bathroom. There is a 2.5 mm supplemental earth bond between the pipes on the bathroom and the water pipe to the shower.

Any problems here?

I hope the "metal appliances" don't include anything fed by plastic pipes...

The shower is 9.5 kw, I have been told that 40 amp RCCB is adequate. Should this not be 42 amp? If I use the 40 amp RCCB, will it be adequate?

If it's rated at 9.5kW at 240V, then 40A would be OK. If that rating is at 230V, or if you can't find out for sure that it isn't, then you should use a breaker of at least 45A.

BTW - RCCB stands for Residual Current Circuit Breaker. I take it that you meant to write MCB - Miniature Circuit Breaker???

MK put earth terms in their CU's labelled "BOND" so people must use them for bonding.

I assume that that's so you can run your supplementary bonding back to the CU of you want, even though you don't have to. But AIUI, main bonding is supposed to go directly to the MET.

 

[balrog]

Hi folks,

There are no plastic pipes in the bathroom. everything is copper. I knew I did not have to earth back to the main point nut I felt it was a good thin to do.

The circuit breaker I have is marked 'Sentry' RCD - 2 Module 40 amp. This was supplied as suitable by my local B+Q. I wanted to have the earth protection as well which is not offered by an MCB. I intend to mount it in an MK Sentry insulated enclosure.

I notice that there is no provision for an earth connection on either the RCD or back box, only live and neutral. The RCD will be mounted right at the start of the cable run. Can the earth from the 10mm supply cable to the shower then connect into the main earth block at the point where the electricity enters the house?

Whilst I am installing the shower myself, it will be checked over and connected by a qualified sparks!

Thank you for your help!

Bob