Truma heater flue pipe

[johnandrew70]

Can any tell me how hot the flu pipe gets on the space heater in the van, I was hoping to run a 240v cable up the panelling where the flu pipe is so that I can put a socket in one of the lockers, there are already 12v and television aerial flex in there but wondered if it would get too hot for 240v cables? Any ideas anyone?

 

[ProfJohnL]

Hello John,

Do not run the cable inside the same space as the flue pipe, it does get too hot. You can get some quite small and neat surved top trunking that does not look too ugly or take up to much space that could be used see:-

http://www.diy.com/nav/fix/electrical/cable-accessories-management/cable-management/trunking/D-line-Self-Adhesive-Micro-Trunking-White-Pack-Of-4-9726456

 

[Trevormc]

If you do go down that route use a high grade Silicone Rubber covered with a temperature rating up to 180ºC.

Trevor

 

[johnandrew70]

Hello John
Thanks for the reply, i did wonder if it would get too hot for 240v cables, but what about the 12v and aeriel cables? surely if it was going to be a problem for these Abbey would not have routed them up there?if they are not such a problem would i be ok in running an HDMI cable down the flu cabinet? if not i guess i will have to go the external route and cover them which is a shame as i didnt want to drill holes in anything, its a shame they dont put a conduit type of trunking in when building the vans for retrofitting

 

[johnandrew70]

Hi trevor any chance you could send me a link for this type of cable?

 

[Trevormc]

Hi John

Sorry I do not have a link to high temperature cables, but they are used in electric heaters that I have built in the past and with a surface temperauture of 70ºC.The main people at the company are away for the next 3 weeks and I will be away for 2 weeks when they are back, sorry I cannot be more helpfull at the moment.

Trevor

 

[johnandrew70]

Hi Trevor i will do a bit of searching on the net and see what i can find, Failing that i'll have to run the cable a different way

do you think the HDMI cable will be ok in the flu cabinet? as i said the aeriel cable and 12v cables run that way, its a nightmare really all i want to do is put the Freesat box and DVD player in the locker out of the way and thought the ideal place would be the same place as the CD player and aeriel booster box

all electrical stuff in one locker and installed so that its not cluttering the place up,

 

[DeliDave_]

Hi,I have put a socket on the outside of the flue cover and used 1.5mm sq heat resistant flex run up inside from local electrical wholesaler with no problems.As far as I know you shouldnt use cable with solid cores.

 

[Beehpee]

I would have thought if there are cables in the flue ducting area already and these have not been affected by the heat from the flue such as any melting or even scorching of the insulation around the existing wires then the answer to your question is obvious, why just because it's carrying 240 volts as opposed to 12 v or a tv signal would it be any more likely to come to any harm, all I would say is when you run the cable through make sure you fix it in the furthest corner of the ducting away from the flue itself, it needs to be fixed so as it cannot move about and actually come into contact with the metal of the flue, other than that I really can't see any problem at all. Re delindaves point about solid core wiring he may well be correct there but to run a tv and DVD I think you mentioned you certainly won't need thick household mains cable which is the type with solid core wires.

BP

 

[johnandrew70]

Hi Dave
i will pop into wicks or somewhere sometime and see what i can find, its not as though we use the heater on gas, just want it to be safe.

 

[johnandrew70]

Hi BP
i know what you are saying but if a 12v cable melts or aeriel cable so what the worst it would do is blow a fuse but with 240v cable it could turn the van into a giant BBQ, the thing is i would not be able to fix the cable in the flu ducting as there is no access to it only at the top and bottom so the cable would be loose inbetween, i think its and external job with a peice of conduit and just run the HDMI cable through the flu space.

 

[DeliDave_]

I think my cable was only about £1 a meter from Insite,BehPee probably knows there in Daventry,and connected to a junction box underneath so a couple of meters was plenty.Also with the circuit breaker and RCD you are probably safer than with 12 volt wires which can cause a serious problem if things go wrong.Good luck with it anyway

 

[johnandrew70]

Hi Dave have they got a website and if so have you got a link to the cable you bought?

 

[DeliDave_]

http://www.insiteelectricaldistributors.co.uk/
just ask for 1.5mm square heat resistant 3 core flex,don't know your location but its easily postable

 

[JohnGriffiths]

Hi BP
i know what you are saying but if a 12v cable melts or aeriel cable so what the worst it would do is blow a fuse but with 240v cable it could turn the van into a giant BBQ, the thing is i would not be able to fix the cable in the flu ducting as there is no access to it only at the top and bottom so the cable would be loose inbetween, i think its and external job with a peice of conduit and just run the HDMI cable through the flu space.

I think 12v should be treated with as much caution as 240v. It has just as much chance of turning a van into a BBQ. I remember as a child my dad showing me what happens to a 30 amp copper wire when shorted across a car battery, i.e. molten within a couple of seconds. It has less volts but the potential (no pun intended) to deliver far more amps. Fires in cars are not always due to petrol leaks.

 

[Guest]

Just thinking out load, but, cable is rated to carry a stated current without voltage drop or overheating, to then install a cable beside and enclosed with a known high heat source, is to my mind, folly!

 

[Dustydog]

My binocular case was in the cupboard next to the flue.
The glue melted and the case fell apart!!
Only a madman would run cables in that flue channel. Sorry to sound harsh but surely our safety comes first

 

[johnandrew70]

yes and this was my question right at the start dustydog, the flu cover already has cables running up it from factory and as i said surely Abbey wouldnt have put them there if it was a fire hazard? its a shame they dont have a box section somewhere that took cables to the locker areas, it would be the same if i decided to install a microwave, i think its got to be the external route instead and drill holes.

 

[ProfJohnL]

Mains low voltage (nominally 230V ac) twin and earth (mains wiring) should not be installed where temperatures can exceed 70C. the main constituant of the cables insulation is PVC which softens significantly and looses some of its physical and dielectric strength as temperature increases.
The area imediately around parts of a Truma or Carver flue pipe can easily reach and exceed that temperature.
I know from past experience that manufacture are warned about running electrical cables close to the flue systems, yet some still do even though it is contrary to the wiring regulations and good sense.

I totally agree with John Griffiths, the same advice applies to extra low voltage (48V and below) cables also.

Gary is correct - except its major folly!

 

[johnandrew70]

Hi John
thank you for your input, now you have me wondering wether i should re-route the factory wiring now haha. we have never used the heater on gas but now if we do i am going to be sniffing for burning smells. i will be going for the external idea with trunking. and might even move the factory cables as for the HDMI cables well i beleive i need to go back to the drawing board and rethink what to do. i am glad i asked the question though and thank you all for all your input.

 

[Damian]

Just a few observations on this subject.
1. Just because the caravan builder put cables in a flue duct does NOT mean that it is safe.
2. Following a caravan builder and doing the same is sheer folly.
3. Solid core cables are NOT allowed to be used anywhere in a caravan, they MUST be multicore flex.
4. ALL electrical items fitted now MUST conform to the latest regulations,ie 17th Edition, however the regulations do not apply retrospectively.
5. If you cannot secure the cable along its route up the flue duct DO NOT fit it in there.
6. How do the manufacturers get away with issuing Certificates Of Conformity ,,,,,,I have no idea, but I do know that not a single caravan built to date conforms to 16th or 17th Edition regulations on many aspects.

 

[GStockton]

Just remembered when I had a 2002 Abbey 417 Vouge. The Ariel stopped working! I traced the cause to the Coax running from the ariel amp in the cupboard down with the flue pipe to the tv outlet point. this cable had melted. Think i had to replace it more than once.

 

[woodsieboy]

I seem to remember that on one of our previous vans,it may have been an Abbey,the heater flue was protected by a heat shield, if as you say Abbey have fitted cables in the void with the flue,I wonder if the flue has a heat shield designed to prevent damage to the cables.
I suspect the only way you will find out is to check inside the void.

 

[johnandrew70]

Hi Woodsieboy
i can see the flu pipe from a small removable panel at the top and i can tell you that there is no heat sheild there at all it makes me smile to think that this flu pipe is literally resting against plywood and can get as hot as it does, dont think i will ever be brave enough to put the heater on on gas

i remember an old lunar we had didnt even have a flu for the heater in the roof, it was in the floor what happened to that idea? saying that it was 25 years old so maybe legislation put pay to that idea.

 

[Damian]

The flue should be supported along its length with flue brackets which keep it a minimum of 55mm from any flammable material.