Cable Type RCD compliance

[nickfryer]

Hi All

I know when wiring a narrowboat that cables must be stranded and not single solid cores.

 

Does it have to be Tri rated cable or can stranded 6491X type cable be used.

 

This is a single insulated type that is used in conduit installations by electricians?

 

It is still stranded but is not as flexible as Tri rated which has more finer strands.?

[nicknorman]

Hi All

I know when wiring a narrowboat that cables must be stranded and not single solid cores.

 

Does it have to be Tri rated cable or can stranded 6491X type cable be used.

 

This is a single insulated type that is used in conduit installations by electricians?

 

It is still stranded but is not as flexible as Tri rated which has more finer strands.?

Pretty sure multistrand cable is not required, but certainly a very good idea. I would not use 6491X because it has few strands of rather thick cable and the strands may be prone to breaking - it is a halfway house to the correct sort of finer multistrand, but why not just use the right stuff! Assuming you are talking about the 12v (or 24v) system then the best sources of cable are automotive electrical. Not sure whether these are Trirated but I don't think that is a requirement for automotive nor boats. For 240v wiring, people usually use 3 conductor flex for the limited mains wiring on boats, and the current limit of 16A that applies to most shore power supplies. Unless of course are going for a large inverter or generator with more than 3.5KW available.

[John V]

Hi All

I know when wiring a narrowboat that cables must be stranded and not single solid cores.

 

Does it have to be Tri rated cable or can stranded 6491X type cable be used.

 

This is a single insulated type that is used in conduit installations by electricians?

 

It is still stranded but is not as flexible as Tri rated which has more finer strands.?

Automotive cables are generally not tri-rate as a lot of them are not rated for 240 volts , if you are using the cable for 12/24 volt on a narrowboat with long cable runs recommend stay away from 6491x as in bigger sizes its difficult to loom due to stiffness.

[by'eck]

Pretty sure multistrand cable is not required, but certainly a very good idea. I would not use 6491X because it has few strands of rather thick cable and the strands may be prone to breaking - it is a halfway house to the correct sort of finer multistrand, but why not just use the right stuff! Assuming you are talking about the 12v (or 24v) system then the best sources of cable are automotive electrical. Not sure whether these are Trirated but I don't think that is a requirement for automotive nor boats. For 240v wiring, people usually use 3 conductor flex for the limited mains wiring on boats, and the current limit of 16A that applies to most shore power supplies. Unless of course are going for a large inverter or generator with more than 3.5KW available.

 

To add to Nick's comments Arctic three core 2.5 mm² multistrand cable is a popular choice and available in blue 50m reels from Screwfix.

 

You can use any left over to make a shore power hook-up cable.

[jonathanA]

The problem with conduit wiring 6941x is it tends to be made up of 7 cores so for larger sizes (4/6/10MM) used on boats each core is fairly chunky. The risk is that this cable will be more prone to breaking with vibration which is why flexible cables are recommended. Tri-rated are fine in my opinion as they are made up typically of a greater number of smaller cores and may be superior to some automaotive cables. I use it becuase it can be more cost effective than automotive cable from fleabay or Vehicle wiring products for instance.

 

I don't know whether the BSS mandate flexible cable for the low voltage systems or not, but for mains it is a recommendation not a mandatory requirement, although most use Artic flex for mains not house T&E.

[rjasmith]

nickfryer, you specifically mention RCD compliance in your thread title. The relevant RCD standard is ISO 13297 and there is a table in the back of it giving the minimum stranding arrangements for different cable core sizes. The table covers all core CSAs from 0.75 to 150mm²! Also there are two cols, Type A General use cables, Type B Cables where frequent flexing is involved. It would take me a while to reproduce the lot on here for you!

 

I could tell you one or two specific sizes if it helps or you may be able to read the ISO for yourself at your library (or even via your home PC if this service is available from the library where you are a member). Actually I've just remembered there is (or was) a norty Polish website that has ISO 13297 (in English) on it as an open .pdf. try Googling for ISO 13297 - you might be lucky!

 

Richard

Edited September 18, 2012 by rjasmith

[OldGoat]

I think BSS gave up the unequal struggle and said that single core conductor would be acceptible. That said I'd not use it for all the other reasons stated. I didn't know that thick strand stuff was still available - I go back to the days of 7/029 and 3/029....

The problem with thistranded stuff is that many / most sockets don't really work with it - they are designed for the single core stuff. However, you can now terminate the cable with a ferrule (?) that sloves the problem.

 

Artic rated cable (a bit if an overkill as you don't need low temperature and highly flexible stuff for the interior of a NB) looks like a less cost solution

[jonathanA]

nickfryer, you specifically mention RCD compliance in your thread title. The relevant RCD standard is ISO 13297 and there is a table in the back of it giving the minimum stranding arrangements for different cable core sizes. The table covers all core CSAs from 0.75 to 150mm²! Also there are two cols, Type A General use cables, Type B Cables where frequent flexing is involved. It would take me a while to reproduce the lot on here for you!

 

 

I'd assumed the OP was referring to the DC wiring and ISO 13297 is the AC iso I think (at least the version I googled is). Anyway tri-rated would appear to exceed the spec for type A.

 

I wouldn't have thought a boat mains electrical system warranted conduit based wiring but I guess some boats are getting quite complex these days...

 

ETA - I'm not claiming any expertise here just my personal views for what they're worth...

Edited September 18, 2012 by jonathanA

[colin stone]

Energy Solutions website has a table of RCD cable standards - www.energy-solutions.co.uk/wiring-standards.html

and lots of other tables.

[nickfryer]

I'd assumed the OP was referring to the DC wiring and ISO 13297 is the AC iso I think (at least the version I googled is). Anyway tri-rated would appear to exceed the spec for type A.

 

I wouldn't have thought a boat mains electrical system warranted conduit based wiring but I guess some boats are getting quite complex these days...

 

ETA - I'm not claiming any expertise here just my personal views for what they're worth...

Thanks for that. Yes it was the DC side I was asking about.

 

Auto cable seems quite expensive but I can get 6491x and tri rated cable at good discounts so is more attractive to me.

 

Tri rated seems to exceed the standard so I may use this.

[rjasmith]

Thanks for that. Yes it was the DC side I was asking about.

 

Auto cable seems quite expensive but I can get 6491x and tri rated cable at good discounts so is more attractive to me.

 

Tri rated seems to exceed the standard so I may use this.

 

Ah OK, I had assumed you were talking AC! The DC system has a different RCD ISO which is ISO 10133 but it has a duplicate of the 13297 table in the back so the min stranding requirements for the two stds are identical. The Polish site also has a copy of this one on it if you managed to find it. (Of course the owner of the site is in danger of ISO coming down on him heavily for breaking their copyright but he seems to have got away with it for a few years now, bless him!).

 

Without checking, I'm pretty sure that tri rated cable does exceed the RCD specs but I'm less sure about 6491X.

 

Richard

[nickfryer]

Ah OK, I had assumed you were talking AC! The DC system has a different RCD ISO which is ISO 10133 but it has a duplicate of the 13297 table in the back so the min stranding requirements for the two stds are identical. The Polish site also has a copy of this one on it if you managed to find it. (Of course the owner of the site is in danger of ISO coming down on him heavily for breaking their copyright but he seems to have got away with it for a few years now, bless him!).

 

Without checking, I'm pretty sure that tri rated cable does exceed the RCD specs but I'm less sure about 6491X.

 

Richard

Thanks for that found them both that will help me.

Nick

[rjasmith]

Thanks for that found them both that will help me.

Nick

 

I had a new look via Google for 10133 and 13297 myself after you posted above. Interestingly the Polish website seems to have gone now but these two elec ISOs have popped up instead on a German one! There seem to be one or two other RCD ISOs out there to look at for free as well (eg ISO 12217 on Stability is on an Aussie site). I wonder why the ISO copyright police haven't found them out yet!

 

Presume you are doing your boat to the RCD then?

 

Richard

Edited September 18, 2012 by rjasmith

[nickfryer]

I had a new look via Google for 10133 and 13297 myself after you posted above. Interestingly the Polish website seems to have gone now but these two elec ISOs have popped up instead on a German one! There seem to be one or two other RCD ISOs out there to look at for free as well (eg ISO 12217 on Stability is on an Aussie site). I wonder why the ISO copyright police haven't found them out yet!

 

Presume you are doing your boat to the RCD then?

 

Richard

Yes I saw that iso 12217.

 

Yes new shell arrives next Saturday Just prepping calcs etc so I can do the build to RCD spec

 

Nick