6mm pyro...

[ETradesmen]

Hello everybody, my name is Michael.

Last week a landlord called me regarding a faulty electric shower that the company tried to re fit under warranty but told him that the cable supplying it was under rated so they couldn't finish the job...

I went to take a look and the property being a hostel type flat in London did not meet 17th edition regulations. There was no RCD present and the consumer unit was older than me (27 years). I looked at the circuit supplying the shower and it was a 6mm twin and earth on a 50amp breaker. This obviously isn't correct as the run was over 15M and the shower was 9.5KW.

Obviously a shower pulling 38amps cannot be fed via a 6mm twin and earth on a 50amp breaker unless you were after an insurance job...

So after wrestling the metal cabinet off the Crabtree fuse board I noticed it was fed via a 6mm pyro. The circuits in the board were a cooker supply, upstairs lights, downstairs lights, immersion, upstairs sockets, downstairs sockets and a shower supply... Is the 6mm pyro capable of such demand?

I couldn't gain access to the meter cupboard to see what the fuse was feeding the flat, but to me it sounds a bit under rated?

The length of run is around 30M and the cable is clipped direct...

Obviously the landlord is asking me why it needs changing if 'its worked perfectly fine all this time'. But I don't really fancy putting my name on a job if I think it's going to be on the ITV headlines the next day.

Your views are welcome.

Michael > NICEIC registered > 10 years in the business

 

[Dean182]

Likewise!

 

[ETradesmen]

Why? Isn't it obvious?

If there is a potential total load of 60amps and the MICC isn't fused correctly or on a 57amp fuse (god knows what size the fuse is, it's old) its either going to blow or catch on fire????

Of course I could just 'not worry' and just install the shower on a separate board, but that isn't the way I do things... I have a company and try my up most to do things correctly. If you guys seriously don't understand what I'm saying you should give up kitchen fitting and get an office job

 

[londonlec]

Why? Isn't it obvious?

If there is a potential total load of 60amps and the MICC isn't fused correctly or on a 57amp fuse (god knows what size the fuse is, it's old) its either going to blow or catch on fire????

Of course I could just 'not worry' and just install the shower on a separate board, but that isn't the way I do things... I have a company and try my up most to do things correctly. If you guys seriously don't understand what I'm saying you should give up kitchen fitting and get an office job

Your the one who doesn't understand pyro and its ratings. But its all good, because your 'NICEIC'.

 

[Dean182]

Wind up?

 

[Guest55]

i am trying so hard not to rip the crap out of this thread ,......mm must...r..r.resist....

;-)

 

[ETradesmen]

Oh dear, here come the sarcastic replies

It was a simple question about a cable rating.

 

[Dean182]

Oh dear.... You couldn't look in the regs book to find out the current carrying capacity of a cable. Clearly you can't grasp the concept of diversity. I have my doubts about you being able to screw back a socket. let alone attempt making an alteration on a board with pyro. And you have the audacity to criticise people on here. Hero

 

[ETradesmen]

Erm I believe you were the one criticising

The reason why I haven't looked it up in my book is because I'm on a forum instead? Diversity? There is none. If you looked at my 1st post you would see the circuits. It would clearly be under rated if the supply was around 57amps.

Thanks for your help.

I'm off now to make love to my GF. Have fun surfing the web and trying to make innocent by standers look like retards.

case closed

 

[Engineer54]

Erm I believe you were the one criticising

The reason why I haven't looked it up in my book is because I'm on a forum instead? Diversity? There is none. If you looked at my 1st post you would see the circuits. It would clearly be under rated if the supply was around 57amps.

Thanks for your help.

I'm off now to make love to my GF. Have fun surfing the web and trying to make innocent by standers look like retards.

case closed

You seem not to have a clue about the workings of MICC cable, so why not give this job over to someone that does. You are correct on one statement, this job could well turn into a can of worms and cost you dearly, purely because you have no experience of MICC cable!!


Oh, and by the way, 6mm heavy duty MICC is more than capable of handling 60+A all day long!! lol!!

 

[ETradesmen]

Oh really engineer?

I won't lie, I have only ever done one job with MICC. If I'm not sure about something I won't touch it.

My initial question was what load it could hold? And it's now spiralled out of control and people are assuming I haven't got a clue...

 

[capitolltd]

Hmm, can't see a problem with any of this.
Assuming twin and earth clipped direct, ok.(47A)
6mm MI would almost certainly be HD, so again ok.
Any thermal damage present? Unlikely
Lets not forget the shower has a fixed load, so no overload protection required. So providing fault protection is adequate leave it.
I wonder of you fully understand the characteristics of the protective devices installed, for instance the fusing factor?
How long does it take for a cable to reach its operating temperature? How long is the shower on for?

Regards

Cap

 

[william1]

i had a question on this recently about what you would need to upgrade from a 7.2KW to a 9.2KW shower unit and its 10mm thermoplastic cable - 22m, 40amp MCB and a 50amp pull switch is this right?

 

[ETradesmen]

Hey cap. As mentioned above I haven't really touched MICC in all my life, so I was a bit cautious in the size if the conductors.

the question isn't about the shower, this topic was aimed at the pyro.

michael

 

[ETradesmen]

9.2KW = 37amps. Nearest MCB to 37amps is 40amps... The run is quite long 22M. Depending on the reference method used to install the cable with added correction factors then you will know if its done right.

bye the sounds of it it's done correctly.

 

[Engineer54]

Hey cap. As mentioned above I haven't really touched MICC in all my life, so I was a bit cautious in the size if the conductors.

the question isn't about the shower, this topic was aimed at the pyro.

michael

You mentioned CU changes i believe, all with MICC outgoing circuits (as i read it). You say you have experience of 1 MICC installation, ...what about refubishment of accessories on existing MICC installs??


As i say, (and i wasn't trying to be funny) if you don't possess the required experience of working with MICC cable then it is far wiser to pass this job on to someone that does know.


I've always allowed more CCC on MICC cables, (based on installation method) than those given in BS7671. In fact, most manufacturers data also give higher ratings too. But then i've been working with the stuff for the greater part of my working life, and that experience tells you things that books can't!! lol!!