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Posted By Topic: underfloor

nick
May 21 2012 21:12

how come underfloor heating has to be on rcd but hot water cylinders dont arent the both elements. one covered in water and one insulated between tiles and waterproofing.
   

pluto
May 21 2012 21:25

The use of an RCD on underfloor heaters is to give additional protection should someone drill a hole or cut the floor by a saw and make contact with the underfloor element which is not able to be seen when drilling or cutting the floor.

In the case of a water heater the cut of wiring and element is unlikely to occur, and you can see the live parts when doing cutting operations.
   

craig
May 22 2012 19:32

wot wiring rule is this?
   

AlecK
May 22 2012 19:57

clause 4.10.

been there for a long time, maybe you need to spend this Friday night at home with the good book and do some catching up
   

craig
May 23 2012 19:52

never seen one before on an rcd but i guess theres a first time for everything.

I notice theres a rule in the book about supporting your wiring by suitable means as well like pinclipping , saddles, ties etc etc, but aalot a sparkies still wont clip.

and now we guna be hit with more amendments, i aint fully caught up as it is on thes book yet.
   

pluto
May 23 2012 21:22

craig May 23 2012 19:52
Your comment 1(part only)
never seen one before on an rcd but i guess theirs a first time for everything.

My comment 1
The prime reason for requiring RCDs on lighting final sub circuits is for the same reason.

The standard writers where concerned that many roofs had been reported as being alive when a roofing nail made contact with a lighting final sub circuit and this had caused deaths on both sides of the Tasman sea.

2 safe-guards there introduced to cover this position; 1. No wiring for 50mm below the roofing material and 2. The use of RCDs as additional protection against contact with the roofing material.

Your comment 2
I notice there is a rule in the book about supporting your wiring by suitable means as well like pin clipping , saddles, ties etc etc, but a lot a sparkies still wont clip.

My comment 2
Clipping cable above the top of the all thermal insulation is a method of getting the full rating of the cabling, the de-rating factor is around 50% of the original current when fully surrounded in thermal insulation, the cost difference and cable between a cable above the thermal installation or buried in thermal insulation can be large and could be saved by use of a few cable clips.

Do the study and think you will find it may be more economic to clip the cable above thermal insulation for the saving in the cable size increased cost alone and the small additional cost for a few cable clips.

Your comment 3
and now we guna be hit with more amendments, i aint fully caught up as it is on thes book yet.

My comments 3
The main changes in the next 12 months are
changed arrangements for recessed luminaries, having to allow for increased levels of thermal insulation to what the NZ Building Code requires.
These additional requirements came in to force 10 November 2011 and the transitional arrangements to allow for better luminaries expired on the 9th May 2012.

Amendment 2 of AS/NZS 3000 introduces increased arrangements for clearance from LPG bottles and reticulated gas (cng)regulators and the need for an isolating switch on the outdoor compressor unit.

And lastly effective 1 July 2013, changes to the CoC and certification of electrical installations. One key changes there will be no need to be CoCs from the EWRB and you use a standard form from the Energy Safe website.
However, you will need to certify all PEW you do, even the replacement of broken or damaged fittings, etc.

Also to become into force is the revised caravan requirements when Elect (safety) regulations No, 2 are issued which is expected to occur in the next 3 months.

Plenty of reading coming up.

   

craig
May 24 2012 20:23

Are those new COCs from the website carbon copyed or are we only going to need a copy for us sparkies , is this pretty much going back to the old permit system .

Pinclipping, you said about pinclipping to get around the derating of cables, doesnt the new regs cancell this out ,that we have to derate cables for fully coverd by insulation. Alot of homes now new and old have insulation in two or 3 layers up to and not limited at 150 to 300mmm thick,It is nearly impossible to get a cable run above this insulation hieght unless you straightline overtop of the insulation ,Cables where accessable should be tidy pincliped or secured in a way that is tradesmanlike. running in the insulation and unsuported is untradesmanlike although sometimes unavoidable nowadays. Are you are saying that if i was to run my cables overtop of this insulation unclipped and myself be a cowboy then it would not require the full derating factor.
   

AlecK
May 24 2012 23:42

Q
Are those new COCs from the website carbon copyed or are we only going to need a copy for us sparkies , is this pretty much going back to the old permit system .
A
Under the permit system you had to get a permit from someone else before starting.
This will still be self-certification after doing the work. Just won\'t have to buy the forms that you fill in. Probably a few other changes as well, the idea was that everythigng including swapping a fitting would need to be certified but that may change, just how that will work remains to be seen. Expect more paperwork around final connection.

Q2
Are you are saying that if i was to run my cables overtop of this insulation unclipped and myself be a cowboy then it would not require the full derating factor.
A2
Yes if run on to- of insulation only needs derating for partly-surrounded.
Same for clipped to joists, and for laid on ceiling.
When \"completely surrounded\" de-rating applies is where there is insulation on all sides of the cable, like when it\'s been run on top of old bats, then covered with new batts.
By clipping your cables you ensure they always have one side not in contact with insulation, so keep clipping. Or else get them right down onto the ceiling, as long as they are either free to move or mechanically protected as per 3.9.4.3.2.

Completely surrounded also kicks in for \"dive-through\" eg at a light fitting, if the length of cable completely surrounded is more than 150 mm, have to de-rate the entire run. With coverable downlights ru of non-coverable control gear, may have to \"dive up\" to connect to the driver / tranny, then the ELV will \"dive down\" to the light.



   

craig
May 25 2012 17:09

that all sounds abit hit and miss, i guess we ll all have to see what the fellas in the powerhouse have planned aeh.
   

Brian H
May 25 2012 20:40

Im running a Personal campaign..D/lights soo yesterday,Pretty below cieling fixtures so cool...(oh and sweety darling,so cost advantageous..)
   

Brian H
May 25 2012 21:52

I b4 E except Rfta C