regs advice on shower cct

[Robin Spark]

Hey guys, had to replace a dodgy shower switch today. Old crabtree board, 6mm twin and earth taken from supply side of main switch to shower consumer unit (30 ma rcd and 40amp breaker).

Shower consumer unit is next to main board so will comply with 434.2.1 and the shower is triton 8.5kw.

After replacing the shower pullcord switch I said to customer that it was a bit dodgy how the 6mm was linked direct from main switch.

Customer said his son installed the shower and cable is a qualified sparky and as far as he was concerned everything was ok. (son not living around here any longer).

He wants me to go back and do some other work, so just needing help on any specific regs I can show customer to prove that the shower cct needs improving.

 

[steptoe]

its fine, maybe not best practice, but no different from splitting in ISCOs really,

the only issue is if the terminals are suitable for 2 cables.

 

[pkbristol]

It ain't rocket science, ultimately that first bit of 6mm (from main switch to shower cu) is protected by the main cut out fuse, it can't be that hard to make the customer realise that. Then again.

 

[Robin Spark]

its fine, maybe not best practice, but no different from splitting in ISCOs really,the only issue is if the terminals are suitable for 2 cables.

Hi Steps,

yes there doesnt seem any problems with the two cables terminated into the main switch which are currently 16mm tails from cutout and 6mm twin and earth to shower C/U.

I didnt take a photo as customer was over my shoulder every step of the way (no pun intended mate ) but I'm sure you have seen it plenty of time.

 

[Manator]

I would agree here, 6mm fed from the supply side should be fused down accordingly, prior to entry to the shower supply. You could use an in line fuse holder, or panel fuse holders to do this.Making any client aware of the dangers, will always be hard, even electricians apparently do not see any problems, hence the question.

 

[Robin Spark]

Customer said he understood regulations changed and that If I could prove to him that it needed changing then he would consider having the work done and came up with the same old line " no problems so far with the way it was installed!".

Just need some regs really to show him if anyone can help?

 

[steptoe]

6mm will carry 40A, over that short a distance in free air anyway,(clipped direct)

I dont honestly see the problem here,

as I said, the only issue I can get would be the method of termination, and the OP says that it is fine in the terminals.

 

[Electroglow]

Huh ?? Pk main cut out fuse? How would a main cut out fuse protect a6mm tande ??

 

[moose man]

Have seen this done before by a company who install showers for disability for a friend of mine told him to call company back as supply 6mm to shower cu was rated lower then incoming fuse at 60a also left blanks out in the end they split the tails with Henley and 16mm tails I did pop round for a cup of tea when company was there but it was a different electrician all good

 

[Electroglow]

Am I missing something?

6mm cable need to be protected accordingly right?? Lol

 

[NozSpark]

The 6mm would be protected by the downstream device anyway which is allowed by regs for short lengths of cable (like you'd get in a bus bar chamber)... Would have been better if it was supplied from the load side of the main switch though

 

[steptoe]

the 6mm is protected by the 40A MCB, cant remember the reg, but for a short run like that the cable can be protected at either end.

think industrial, maybe 200A per phase, how big do you think the cables coming off the busbars are?

---------- Post Auto-Merged at 23:48 ---------- Previous post was made at 23:47 ----------

pushy

 

[NozSpark]

Shovey

I dd "like" your post, but forum won't let me,,, I can't reply with quote either for some reason:O

 

[Electroglow]

Ye but.. In my mind as I read it (drunk tho) there was a 6mm cable feeding a shower cu coming off the 100 amp main fuse?

If it come from the 40A mcb then I see. That to be acceptable

I'm confused bout the 100A main fuse bit

 

[steptoe]

it doesnt matter,

think a spur off a ring, a 2.5 protected by a 32A MCB, but, its protected the the max it can draw being 13A, you could even wire a spur in 1.5 if you wanted to.

the 6mm is protected by the max demand available which is governed by the 40A MCB.

 

[NozSpark]

If I've found the right reg it's Reg 433.2.2 page 82 of BGB

 

[Robin Spark]

the 6mm is protected by the 40A MCB, cant remember the reg, but for a short run like that the cable can be protected at either end.think industrial, maybe 200A per phase, how big do you think the cables coming off the busbars are?

---------- Post Auto-Merged at 23:48 ---------- Previous post was made at 23:47 ----------

pushy

434.2.1 Allows this where the csa of the cable reduces then just as long as the run is no longer than 3metres to the new protective device and no further branch ccts or socket outlets.

 

[NozSpark]

Steps,,, 433.1.103 says that the line and neutral conductors need to be a minimum of 2.5mm,,,,, so 1.5mm would be non-compliant

 

[Electroglow]

I'm stupid lol just remember that the rcd unit of the shower is 40a lol I was thinking of a rcd cu with a 40 a mcb told I in drunk lol with a 100 or80 amp main fuse

 

[steptoe]

Steps,,, 433.1.103 says that the line and neutral conductors need to be a minimum of 2.5mm,,,,, so 1.5mm would be non-compliant

well that was obviously a sh*7 example then? wasnt it? :Blushing

---------- Post Auto-Merged at 00:04 ---------- Previous post was made at 00:03 ----------

I'm stupid lol just remember that the rcd unit of the shower is 40a lol I was thinking of a rcd cu with a 40 a mcb told I in drunk lol

thats irrelevant, as long as the OCPD is low enough to protect the cable.