Newly Floored Attic, What to do with Cables?

Howyas,

I finished flooring the attic and ran all the cables that were supported over the rafters above the floor because I didn't want to derate them or lose access. I'm just wondering what the best thing to do with them now is?
My preferred method would be to pin them to the flooring under earthed galvanised steel inverted C-channel rather than elevating them creating a trip hazard or encouraging them being pulled outtov circuit by shifting gubbins.

Also I want to put a socket up there from an existing socket circuit. Do I have to use NYMJ or is flex suitable?

Of course I'll be getting a REC to do all this work...the question is entirely academic...

Stravos Murphy

How often do you need access to them in reality? IMO take up the flooring again, cross batten to accommodate the wiring and put down the flooring. Problem solved.

Risteard81

Sir Liamalot wrote: »

Howyas,

Of course I'll be getting a REC to do all this work...the question is entirely academic...

Then just leave it to the REC and don't overly concern yourself with what his methods will be.

Stravos Murphy

Stravos Murphy wrote: »

How often do you need access to them in reality?

Eh, you never know.
Often enough to appreciate serviceability. Is conduit verboten?

Stravos Murphy

I can only imagine flooring an attic to leave the wiring exposed must have been a nightmare. Notching flooring, sliding flooring along joices under wires, possible damaging wiring etc. Again does one need to access to a switch wire for eaxample?

the_pen_turner

i think i would just tape them down. any conduit will be in the way and a trip hasard

Not at all and all the cables are in fine fettle.

I want access in case I want to have them rearranged and I'm not in the habit of installing useful things in inaccessible places.

Stravos Murphy

I'm missing the point of this thread I think, rearranging cables?

Water John

Each to their own but I never heard or saw of any one doing it.

the_pen_turner

the_pen_turner wrote: »

i think i would just tape them down. any conduit will be in the way and a trip hasard

I'm hoping for a more durable solution.



Would something like that comply with regs. or is there any?
All I've been able to find on the issue that cables must be secured.

Stravos Murphy

Stravos Murphy wrote: »

I'm missing the point of this thread I think, rearranging cables?

Indeed I think you are.
Sometimes I find better circuit layouts than what is installed as standard and I implement them if improvements in automation, efficiency or power source are more suitable.

I have 3 phases in my house, one from the grid two homebrew off batteries, a 12VDC workshop radial and a 48VDC house supply. Mostly they're a work in progress.

the_pen_turner

dont know about the regs but i dont like the sharp edges

ted1

Sir Liamalot wrote: »

Indeed I think you are.
Sometimes I find better circuit layouts than what is installed as standard and I implement them if improvements in automation, efficiency or power source are more suitable.

I have 3 phases in my house, one from the grid two homebrew off batteries, a 12VDC workshop radial and a 48VDC house supply. Mostly they're a work in progress.

I wouldn't call that 3 phases.

Stravos Murphy

Sir Liamalot wrote: »

Indeed I think you are.
Sometimes I find better circuit layouts than what is installed as standard and I implement them if improvements in automation, efficiency or power source are more suitable.

I have 3 phases in my house, one from the grid two homebrew off batteries, a 12VDC workshop radial and a 48VDC house supply. Mostly they're a work in progress.

Can you post a pic of your floored attic?

the_pen_turner

the_pen_turner wrote: »

dont know about the regs but i dont like the sharp edges

Well they'll be pinned with the cable inside it, screws holding the corners down and the whole lot bonded...theoretically, unless anyone can enlighten me why it's a bad idea other than for artistic reasons.

Stravos Murphy wrote: »

Can you post a pic of your floored attic?

Yurp, can do, tomorrow though.

ted1 wrote: »

I wouldn't call that 3 phases.

Why not?
3 x single phases all completely isolated.
They can be synced as one but it's very complicated...and a grid tie inverter that's hibernating.

the_pen_turner

sharp edgrs on the outside to get caught on. cable would be safe thow

aido79

To be honest I think you are making this harder than it needs to be and you are going to end up with an unsightly finish with trip hazards all over the place.

You probably would have been better off putting more time into planning the flooring so that if you really wanted access to the cables all you would have to do is lift a narrow strip of wood covering the cable.

ted1

Sir Liamalot wrote: »

Why not?
3 x single phases all completely isolated.
They can be synced as one but it's very complicated...and a grid tie inverter that's hibernating.

i have a loads of batteries in my drawer I must have a couple of dozen phases.

You have 230VAC batteries? That's impressive.

eeguy

Sir Liamalot wrote: »

I have 3 phases in my house, one from the grid two homebrew off batteries, a 12VDC workshop radial and a 48VDC house supply. Mostly they're a work in progress.

You have 3 different voltages maybe?

ted1

Sir Liamalot wrote: »

You have 230VAC batteries? That's impressive.

I just need to add an invertor.

Sir Liamalot

Sir Liamalot wrote: »

I have 3 phases in my house, one from the grid two homebrew off batteries...

via a 2.5kVA battery inverter and a 6kVA battery inverter
making 3 phases at 230VAC


Also....

Sir Liamalot wrote: »

a 12VDC workshop radial and a 48VDC house supply. Mostly they're a work in progress.

Stravos Murphy

I'm still struggling with these three phases.

aido79

Sir Liamalot wrote: »

via a 2.5kVA battery inverter and a 6kVA battery inverter
making 3 phases at 230VAC


Also....

Try connecting a 3 phase appliance to that and see what happens. My guess is it will quickly go on fire.

Unless you can come up with a way of ensuring that the 3 "phases" are offset by 120 degrees from each other then you don't have 3 phase...you have 3 supplies. There's a big difference.

I never said I had a 3 phase supply. I said I had 3 phases in the house.

Stravos Murphy

Is a dc supply called a phase now?

eeguy

Sir Liamalot wrote: »

I never said I had a 3 phase supply. I said I had 3 phases in the house.

You're right, kind of. It's just a very confusing terminology.

You have 3 separate mains supplies.

Stravos Murphy

Stravos Murphy wrote: »

Is a dc supply called a phase now?

No it's only high or low. It was never my intention to suggest it was.

I have three out of sync phases or supplies that all come from different sources. One is the national grid, one is a base load changeover, the last is a heavy consumer changeover. Yes if I cross them things go bang. Two of these supplies are derived from from a 12.5kWh 48VDC battery via inverters

I've tapped the same battery for a 48VDC bus and I have a 12V true DC radial.

...gorsh and all I wanted to know was if floor mounted conduit is kosher in an unoccupied space...

Stravos Murphy

I will have 3 phases tomorrow when I have three cars in the yard.

aido79

Sir Liamalot wrote: »

I never said I had a 3 phase supply. I said I had 3 phases in the house.

You are getting the terminology mixed up. You have 3 supplies...not 3 phases.


How many phases do you see here?:

Stravos Murphy

We are poking the bear now.

I see many standing gensets.

aido79

Sir Liamalot wrote: »

I see many standing gensets.

But you can agree they are supplies and not phases?

To answer your other question..floor mounted conduit is ok but not the easiest way to do it. It would be much easier to rethink your flooring and will be a better job in the end.

A phase is subjective to a supply?

kramer1

Floor trunking

air

While SL explained it poorly at first, he clearly has 3 phases, just not a normal synchronised 3 phase supply.
If he only ever runs single phase loads from it - as would be common in many buildings with 3 phase incomers, then there isn't going to be any major differences in the wiring.

The bigger issue is that when feeding normal AC distribution kit with an inverter, the inverter is unlikely to be able to supply the fault current necessary to trip overcurrent devices within the specified time period.

air

If you count batteries as supplies (which I do) then I have 6

12VDC Battery: 1.5kWh
48VDC Battery: 12.5kWh
2.5kVA Inverter 48VDC -> 230VAC
6kVA Inverter 48VDC -> 230VAC
600W Grid Tie Inverter 45VDC > 125VDC -> 230VAC
National Grid: 63A @ 240V

if I need more I have 2.75kWh @ 12VDC in my camper I can take another 600W mollified square waiver phase from on a fly lead.

They run isolated (except for grid tie) and simultaneously.
Theoretically I can sync the inverters as one 9.1kVA inverter with about 23.5kVA surge but that would be cruel to such a small battery.

air wrote: »

The bigger issue is that when feeding normal AC distribution kit with an inverter, the inverter is unlikely to be able to supply the fault current necessary to trip overcurrent devices within the specified time period.

Would be an issue if you fed an inverter to a mains distribution board, not so much when you feed mains to an inverter distribution board.

Thanks for the advice Aido.
I'm building a trench but my cheapo router expired after a hot supper.

2011

Sir Liamalot wrote: »

Also I want to put a socket up there from an existing socket circuit. Do I have to use NYMJ or is flex suitable?

3 x 2.5 mm flex or NYMJ would be suitable.

Not at all and all the cables are in fine fettle.

What is the issue with them? I would carry out an insulation resistance test on these cables at a minimum. Even if they are ELV they may be a fire hazard (depending on what is wrong with them of course).

Would something like that comply with regs. or is there any?
All I've been able to find on the issue that cables must be secured.

Strictly speaking cabling in the attic should be run around the edges. To comply with regulations proper mechanical protection should be provided to all acting that is at risk to getting a knock or squashed. I think that an attic that is used for storage presents a risk to cabling. What is shown in the above photo could provide the necessary protection, but I think it is not a great solution as it could crush cabling, could result in tight bending radius of some cables, would be impractical, would need to be bonded, is not designed for this application and would be a bit of a gunter.

Sometimes I find better circuit layouts than what is installed as standard and I implement them if improvements in automation, efficiency or power source are more suitable.

This sounds like an evolving hobby. All the more reason not to go with your restrictive suggestion.

I have 3 phases in my house, one from the grid two homebrew off batteries, a 12VDC workshop radial and a 48VDC house supply. Mostly they're a work in progress.

So now I would be thinking about voltage segregation i.e. ELV cabling not sharing the same containment as LV cabling. This would align with best practice.

aido79 wrote: »

You probably would have been better off putting more time into planning the flooring so that if you really wanted access to the cables all you would have to do is lift a narrow strip of wood covering the cable.

This would not comply with the regulations. There is a risk of a cable being driven through the cabling at a later date. Cabling without mechanical protection should not be close to the surface of wooden flooring.

My solution: Use large plastic trunking such as 2 x 4" Marshall Tufflex.
Advantages:
- Easy access to all cabling making it possible to add / remove cabling
- Cheap
- No bonding / earthing required
- Robust, you could even walk on it.
- Multi compartment is possible
- Simple to install without disconnecting anything.
- Possible to mount sockets on it.
- Conduit can be connected to it.

Keep it simple!