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

 

[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!!

 

[ETradesmen]

I am totally capable of terminating MICC. I know what's involved and how little it takes to mess it up.

i won't attempt to change the board as that wasn't what I was asked to do..

just a quick question, do you think it would be beneficial to rewire the place rather than trying to work with the existing MICC's if the Landlord wanted a mass of alterations?

this hasn't been discussed with him I'm just curious

 

[Engineer54]

I am totally capable of terminating MICC. I know what's involved and how little it takes to mess it up.

i won't attempt to change the board as that wasn't what I was asked to do..

just a quick question, do you think it would be beneficial to rewire the place rather than trying to work with the existing MICC's if the Landlord wanted a mass of alterations?

this hasn't been discussed with him I'm just curious

I'm the wrong person to ask about ripping out a MICC installation, in favour or an inferior wiring system. ... i'll leave that question to others!! lol!!!

 

[UNG]

I am totally capable of terminating MICC. I know what's involved and how little it takes to mess it up.

i won't attempt to change the board as that wasn't what I was asked to do..

just a quick question, do you think it would be beneficial to rewire the place rather than trying to work with the existing MICC's if the Landlord wanted a mass of alterations?

this hasn't been discussed with him I'm just curious

Terminating MI is just a small part of using it and working with it your comments highlight a lack of knowledge and experience with MI

Why is it that the answer to a problem where MI is installed is rip it out. This just highlights a hole in knowledge base of many sparks that have entered the industry in recent times

 

[DPG]

Pyro > mineral insulated copper conductor.
PVC > twin and earth

are you a plumber?

I think he meant which parts of the run are in pvc and which are in pyro. He wasn't asking what pvc and pyro means! Daz

 

[Fin170]

I've not had the pleasure of getting to work with pyro but I know it will happily run at max current whilst hitting it with a hammer and still outlive me after


And just to derail the thread further, stick the bloody shower on a 32a MCB/RCBO :shades_smile:

 

[Brendan976]

Pyro and armoured is all that I did for 18 months on a power station , I got to love pyro which is more than I can say for armoured given the size of some of the armoured cables, I used to struggle to terminate those suckers with hydraulic crimpers.

Ben

 

[Stroppy]

I'd just like to say that those who think us lot of domestic installers who have no experience of MI cable are somehow stupid need to wind their necks in - its not our fault we haven't had exposure to this type of cable, as these days it is relatively rare, unless you routinely wire churches or factories. I know its a wonderful cable which will still be around and fit for service floating in space when the world has blown up, but if I came across some and needed to do something with it I would sooner replace it with some T&E which I am familiar with rather than try and fiddle with it and drip snot in it and ruin it, or try to find someone who knows what they are doing with it.

 

[Fin170]

snip

I only got to use it in college and a few rare terminations but even then I found it to be fantastic stuff

Problem is it's too damn expensive for anything other than anything specifying it. After how paranoid this forum has made me over RCD failures and the consequences of no lights etc I wondered how much it would cost just to run 1 or 2 switch drops in it so RCD protection could be omitted....nearly fainted just at the cost of the tools

Also couldn't work out why some of the council flats I've been in had been rewired with T&E in surface trucking when it was all done in MICC probably in the 70s or 80s

Work experience wanted :lol:

 

[UNG]

I'd just like to say that those who think us lot of domestic installers who have no experience of MI cable are somehow stupid need to wind their necks in - its not our fault we haven't had exposure to this type of cable, as these days it is relatively rare, unless you routinely wire churches or factories. I know its a wonderful cable which will still be around and fit for service floating in space when the world has blown up, but if I came across some and needed to do something with it I would sooner replace it with some T&E which I am familiar with rather than try and fiddle with it and drip snot in it and ruin it, or try to find someone who knows what they are doing with it.

Your comment works both ways it's surprising how the DI card gets played when you find a wiring system you are not conversant with and how quickly you will replace it with T&E rather than pass on the job to someone with the experience to work on these wiring systems

I only got to use it in college and a few rare terminations but even then I found it to be fantastic stuff

Problem is it's too damn expensive for anything other than anything specifying it. After how paranoid this forum has made me over RCD failures and the consequences of no lights etc I wondered how much it would cost just to run 1 or 2 switch drops in it so RCD protection could be omitted....nearly fainted just at the cost of the tools

Also couldn't work out why some of the council flats I've been in had been rewired with T&E in surface trucking when it was all done in MICC probably in the 70s or 80s

Work experience wanted :lol:

There are ways to work on MI without all of the expensive branded tools it just needs a bit of imagination and improvisation

 

[Brendan976]

There are ways to work on MI without all of the expensive branded tools it just needs a bit of imagination and improvisation

Very true, but you cant beat the good old joi stripper.

 

[UNG]

Very true, but you cant beat the good old joi stripper.

If your using the Pyrotenax pyro the joistripper works well but the other manufacturers pyro sometimes has a poorly annealed seam weld and it's easier to use a T bar.

The other problem with the joistripper it only works on the small sizes and I've just looked at the price £76 =vat think mine cost £19 when I got it

 

[Des 56]

Watching someone trying to Strip Pyro with side cutters would reveal many things to me

You’ve got to ask yourself one question: "Do I feel lucky?" Well do ya, punk?

 

[Brendan976]

I got my supplied to me in 1976 no idea how much it cost, I made some t bars back then for the bigger pyro. I still have my ringing tool somewhere and the pyro straightners for what they were worth.

Ben

 

[Engineer54]

Watching someone trying to Strip Pyro with side cutters would reveal many things to me

You’ve got to ask yourself one question: "Do I feel lucky?" Well do ya, punk?

I'm afraid i've had to use side cutters and long nose pliers on more than a few occasions in the past, it's no big deal really!! ....Unless you try to strip it like you would a PVC cable!! lol!!

 

[electric will]

I've never had to use pyro but I might buy a few meters to have a play with,
regarding E54s post I'm guessing your using the long nose pliers to open it, like youd open a tin of corned beef?

 

[Des 56]

I'm afraid i've had to use side cutters and long nose pliers on more than a few occasions in the past, it's no big deal really!! ....Unless you try to strip it like you would a PVC cable!! lol!!

That was the point I was making I could happily strip away with a pair of cutters and make an end off before others have set up their stripping tool and blunt blades. poaaibly mangling the sheath in the process

Using side cutters as you know has a knack to it
It can be a laugh a minute, watching someone try it who is not used to doing so
Those who have worked with pyro can also use the tools or improvise with whatever is at hand,the skill of the person can sometmes be judged when the cutters come out

 

[Engineer54]

haha!!! OK i'm with you now Des!! ...Just wiping the sleep out of my eyes, ...i should be ok after my second coffee!! lol!!

 

[wade88]

Well different cable types aside, wont be long before this takes off.

Wireless Power May Cut the Cord for Plug-In Devices, Including Cars

 

[Engineer54]

I've never had to use pyro but I might buy a few meters to have a play with,
regarding E54s post I'm guessing your using the long nose pliers to open it, like youd open a tin of corned beef?

That's about the size of it Yes!! just don't use the short flimsy long nose pliers, mine are like a Mechanic's, with a nose about 6 to 7'' long. Always better to make your own emergency stripping bar whenever possible, it's a much easier and faster task then, especially if your terminating into a panel or CU etc... lol!!

Like many of the others here, that have extensive experience of working with MICC, i can terminate and make off the pot end without any of the specialised tools normally required/associated with terminating MICC... lol!!

 

[Engineer54]

Well different cable types aside, wont be long before this takes off.

Wireless Power May Cut the Cord for Plug-In Devices, Including Cars

Tesla had a viable system for drawing power wireless!! That idea was soon purposely lost in the file 13 achieves by the power industry of the time!! lol!!