What a shower

[Duncan Bennett]

Just been along to see a potential client. They want an estimate to upgrade the fuse in their 1 way splittersplitter. It is currently a 30amp cartridge fuse.

They just had a bathroom company redo the bathroom, and they changed the shower to a new 9.8kw unit - which their electrician installed.

I had a look at it and the supply cable which disappears under the floor at the old fuseboard only reappears in a cord pull isolator in the bathroom - maybe 5m away. the problem I have is that the load cable from the splitter is obviously 6mm T&E.

so, I = p/v 9800/230 = 42.61a

Table 4D5 allows for 47amps - clipped direct - but this cable has a way to go and I'd say that at least a third of the run is sunk in plaster and a good bit of that in a new tiling job. So replacing the supply will be messy at best - as well as expensive, and the job has just been done. I can't believe the spark would have let it run through a 30amp cartridge fuse in any case.

I know there should be some allowance given for a short load duration - but what are your thoughts?

 

[telectrix]

cable sunk in plaster etc. is still method C. it's only insulated walls that require derating. personally, i'd connect up and clamp meter the cable. bet you can't get it to read more than 38A.

 

[Duncan Bennett]

Yeah. My first thoughts were to just upgrade the cartridge fuse and splitter to and RCD and CB and suggest changing the shower. I'll check again to see if there is any wall insulation, but I think it probably runs under the floor to the bathroom and then up the wall to the isolator before dropping back down at the other side of the bathroom behind the tiling.

 

[i=p/u]

If say when you clamp it, it's v hot at 31A but not your point, I'd say is fine but it's you has to live with it, can you..

 

[telectrix]

bloody 'ell, I=pu, what them scots twerps putting in your water?

 

[i=p/u]

Aye they driving me mad.

What I ment to say was if your happy I'm happy

 

[Guitarist]

Just make sure that the cable is protected by the OCPD. If it trips/blows due to them being in too long, then they will have to take shorter showers...

 

[Darkwood]

Just been along to see a potential client. They want an estimate to upgrade the fuse in their 1 way splittersplitter. It is currently a 30amp cartridge fuse.

They just had a bathroom company redo the bathroom, and they changed the shower to a new 9.8kw unit - which their electrician installed.

I had a look at it and the supply cable which disappears under the floor at the old fuseboard only reappears in a cord pull isolator in the bathroom - maybe 5m away. the problem I have is that the load cable from the splitter is obviously 6mm T&E.

so, I = p/v 9800/230 = 42.61a

Table 4D5 allows for 47amps - clipped direct - but this cable has a way to go and I'd say that at least a third of the run is sunk in plaster and a good bit of that in a new tiling job. So replacing the supply will be messy at best - as well as expensive, and the job has just been done. I can't believe the spark would have let it run through a 30amp cartridge fuse in any case.

I know there should be some allowance given for a short load duration - but what are your thoughts?

You cannot rely on the time curve of the OCPD to effectively draw more current than the rating of the device just because you don't have the load on long enough to make it trip.

Calculate the CCC of the cable with its installation method if this is still over the load demand then fit a 50amp mcb and ensure your Zs value still comply ... this would meet regulations although im only suggestion this method as your situation would need a rewire otherwise i normally wouldn't recommend Omitting O/L protection in domestic.

 

[Engineer54]

so, I = p/v 9800/230 = 42.61a

Be even less (around 40/41A) if you use the Real nominal voltage instead of the make believe one!! lol!! Also as Tel has implied above, these shower's stated ratings, are often not actually what you get!!

 

[Guitarist]

Be even less (around 40/41A) if you use the Real nominal voltage instead of the make believe one!! lol!! Also as Tel has implied above, these shower's stated ratings, are often not actually what you get!!

Agree here, although I did measure 235 at a house a few days ago....

 

[Engineer54]

Agree here, although I did measure 235 at a house a few days ago....

Probably at, or near the end of a long networks distribution cable...

 

[Hawkmoon]

Be even less (around 40/41A) if you use the Real nominal voltage instead of the make believe one!! lol!! Also as Tel has implied above, these shower's stated ratings, are often not actually what you get!!

May be having a blond moment here but doesn't this depend on how the manufacturer calculates the advertised kW? I mean from which level of voltage?

 

[Engineer54]

Manufactures like to state maximum figures, it looks better on the box as far as they are concerned!! lol!!

 

[HandySparks]

May be having a blond moment here but doesn't this depend on how the manufacturer calculates the advertised kW? I mean from which level of voltage?

Indeed. The 9.8kW will almost certainly be specified at 240V, with a rating of about 9.0kW at 230V. Currents of 40.8A and 39.1A respectively.

 

[Engineer54]

Nope, they will generally just state the highest KW rating on the box. You might see something relating to voltage related KW ratings in the spec/data but i wouldn't hold my breath.... lol!!

To be honest, i can't really see the point to showers over 8 KW /8.5 KW...

 

[Rockingit]

To be honest, i can't really see the point to showers over 8 KW /8.5 KW...

Having swapped an 8.5KW for an 11KW in my own bathroom......nor can I! No appreciable difference at all.

 

[jamie-spark]

Usually on the tank or box it will express kW for 240/230

9.8kw at 240v
9.5kw at 230v

 

[jamie-spark]

http://www.showerdoc.com/mira-heater-tank-9-8-kw-9-0-kw-230-v-ac-1563-504

 

[telectrix]

Having swapped an 8.5KW for an 11KW in my own bathroom......nor can I! No appreciable difference at all.

pointless. anyway. showers are pants. how the hell can you keep your scotch in one hand and a smoke in the other. give me a jacuzzi bath any day.

 

[Rockingit]

pointless. anyway. showers are pants. how the hell can you keep your scotch in one hand and a smoke in the other. give me a jacuzzi bath any day.

Indeed. It only happened because the old one was shagged and I spotted a good deal on the bigger one. I'm a fan of the big long soak, too.