Thoughts please, SWA vs T&E

[GBDamo]

I have a TPN board that will feed 8-10 sub boards. The loads on each board are negligible 5-10 amps peak but mostly 1-2 amps.

The distribution circuits will be fed in 6mm mostly for VD reasons but also to allow some selectivity on the OCPD(MCB) my dilemma is SWA or T&E.

The route is 98% tray before entering a room and feeding a surface mounted consumer unit.

For aesthetic reasons they want the cables in the wall, fair enough, but I'm in a catch 22.

If SWA I'd never be able to gland into the back of the CUs and the SWA would end up surface, if T&E the cable would be in a timber partition but less that 50mm deep thus requiring RCD which completely negates the principle of sub devision of circuits.

1, Am I going OTT worrying about this c0.5m drop from the ceiling to the back of the CU?

2, My "Solution" is to mount a galvanised box above the ceiling, gland the T&E through into some earthed steel flexicon, down inside the wall and into the back of the CU.

3, Am I missing a more obvious simpler solution?

Thanks.

 

[davesparks]

Gland the SWA into a flush metal box behind the CU, can be a normal back box, terminal box or adaptable box.

In a stud wall I've even glanded SWA into a galv inspection elbow and bushed that onto the back of the CU.

 

[westward10]

As above use a steel adaptable box fixed to the back using its four cover fixing points.

 

[Dustydazzler]

I have seen people gland into a through box during 1st fix ( which is often left floating and just pull the single cores through the plaster board wall

 

[GBDamo]

I jave thought about glanding off behind the CUs but aren't these supposed to be accessible for inspection?

 

[westward10]

If the armour is not acting as the cpc then it is not important as the other end will be accessible.

 

[Dustydazzler]

I jave thought about glanding off behind the CUs but aren't these supposed to be accessible for inspection?

a club hammer to the plaster board would soon make an inspection hole

 

[timhoward]

The "last few cm" of a distribution circuit supply requiring RCD protection is one of the irritations of the regs.
I've long thought that anyone who decides to go drilling in the 20cm above a CU deserves to become an integral part of a new circuit.
Bring back the 16th edition!

 

[davesparks]

The "last few cm" of a distribution circuit supply requiring RCD protection is one of the irritations of the regs.
I've long thought that anyone who decides to go drilling in the 20cm above a CU deserves to become an integral part of a new circuit.
Bring back the 16th edition!

If its just the last drop down/up to the CU then it's easy enough to give it mechanical protection. A bit of galv conduit or even a metal plate is all you need.

 

[James]

I go out flying kites with the grandkids far more often than I drill holes in the walls of my house.
their is some loose advice out there if you search for it that recommends not to fly kites near overhead power lines. (The sparks amongst us will already know it’s a bad idea)

there are regulations that prohibit running cables an inch below the surface from a consumer unit to the ceiling (230v) where no sane person would drill a hole but a bit of advice not to mess with the 11,000v overhead lines.
over the top maybe?

 

[davesparks]

I go out flying kites with the grandkids far more often than I drill holes in the walls of my house.
their is some loose advice out there if you search for it that recommends not to fly kites near overhead power lines. (The sparks amongst us will already know it’s a bad idea)

there are regulations that prohibit running cables an inch below the surface from a consumer unit to the ceiling (230v) where no sane person would drill a hole but a bit of advice not to mess with the 11,000v overhead lines.
over the top maybe?

I'd rather over the top regulations than one single person's death, one single child growing up without a parent, one family left destitute as the bread-winner is dead.

 

[bigspark17]

Swa far better choice, gland with bango/earth supply side and dont gland it cu side as-long as you have a separate earth conductor of course.

 

[timhoward]

If its just the last drop down/up to the CU then it's easy enough to give it mechanical protection. A bit of galv conduit or even a metal plate is all you need.

I was thinking of situations where there’s enough room to fish down without disturbing decoration but not enough room to mechanically protect it. E.g in a commercial from above suspended ceiling down behind the plasterboard. I’m happy to learn any tricks if there are any.
But I agree that if redecoration is going to happen it’s simple enough.
(Btw I don’t really want anyone to die of course, I was just venting that there is a trend of over regulating and common sense eroding away. We stop short of the requirements of USA wiring regs at least)

 

[UNG]

Can you recess the CU into the wall and gland the armoured straight into the top as you fit it

 

[GBDamo]

I'd rather over the top regulations than one single person's death, one single child growing up without a parent, one family left destitute as the bread-winner is dead.

It's that thinking that has stiffed the west, the "one death is too many".

Progress requires risk, if you take zero risk you get zero progress. But, and its a huge but, there is a ballance.

I'd further berate the zero risk advocates on account of their hypocrisy, it's not zero risk they want it's zero visible risk, they're happy to profit from heavy industry in India and China, they can't see those deaths.

No one is advocating sending kids down a mine, we'll unless they're brown kids in an African mine, but that's acceptable because, well, I'd have to change my iPhone less frequently.

I've always found it odd the places we don't apply the "One death is too many" rule. Why do we allow leisure use of the roads? How many cyclists die every year whilst playing on the roads?

Swimming in the sea, lakes and rivers; ban them.

Motorcycles; ban them.

Smoking, drinking, sex; ban them all.

You'd be bored to tears but you'd be safe.

 

[DPG]

It's that thinking that has stiffed the west, the "one death is too many".

Progress requires risk, if you take zero risk you get zero progress. But, and its a huge but, there is a ballance.

I'd further berate the zero risk advocates on account of their hypocrisy, it's not zero risk they want it's zero visible risk, they're happy to profit from heavy industry in India and China, they can't see those deaths.

No one is advocating sending kids down a mine, we'll unless they're brown kids in an African mine, but that's acceptable because, well, I'd have to change my iPhone less frequently.

I've always found it odd the places we don't apply the "One death is too many" rule. Why do we allow leisure use of the roads? How many cyclists die every year whilst playing on the roads?

Swimming in the sea, lakes and rivers; ban them.

Motorcycles; ban them.

Smoking, drinking, sex; ban them all.

You'd be bored to tears but you'd be safe.

Look at the 'Vision zero' scheme.

 

[Dustydazzler]

Watch Demolition Man

Ban anything and everything that may cause an injury or that is bad for your own health

 

[sparkymark77]

I’ve had this dilemma before and done various things included those mentioned before. For a t&e I ran it in 25mm steel conduit with a terminal box on the end, then earthed the terminal box to the cu earth bar. Made sure the screw in the terminal box was accessible through the knockout at the back of the cu. For swa just take it in to the back of the cu and put the armouring in to the earth bar if it needs to be accessible. If not I agree that terminating the swa into a box behind is nearer and looks more professional!

 

[UNG]

It's that thinking that has stiffed the west, the "one death is too many".

Progress requires risk, if you take zero risk you get zero progress. But, and its a huge but, there is a ballance.

I'd further berate the zero risk advocates on account of their hypocrisy, it's not zero risk they want it's zero visible risk, they're happy to profit from heavy industry in India and China, they can't see those deaths.

No one is advocate sending kids down a mine, we'll unless they're brown kids in an African mine, but that's acceptable because, we'll, I'd have to change my iPhone less frequently.

I've always found it odd the places we don't apply the "One death is too many" rule. Why do we allow leisure use of the roads? How many cyclists die every year whilst playing on the roads?

Swimming in the see, lakes and rivers; ban them.

Motorcycles; ban them.

Smoking, drinking, sex; ban them all.

You'd be bored to tears but you'd be safe.

We have to accept that living is dangerous some of the fittest and heathiest people I have known have died way before they should, life is a lottery and when your number is up that is it IMO
We work with electricity and it can be dangerous so why do we do it, more to the point why does anyone meddle with electricity should we ban it, not sure that would go down too well although it would reduce bills

The trouble these days some people have found the risk before even identifying the hazard

 

[davesparks]

I've always found it odd the places we don't apply the "One death is too many" rule. Why do we allow leisure use of the roads? How many cyclists die every year whilst playing on the roads?

Swimming in the sea, lakes and rivers; ban them.

Motorcycles; ban them.

Smoking, drinking, sex; ban them all.

You'd be bored to tears but you'd be safe.

How many deaths aren't too many then?

Why shouldn't we strive to prevent deaths on the roads?