Fire Hazard on narrowboats

[hawkers]

I was with a marine engineer yesterday whilst he was conducting a survey for a possible purchase of a narrowboat. During the survey he pointed out that the insulation was polystyrene which apparently causes reaction to plastic electric wiring sheathing. Over time he said the sheathing becomes brittle and thus could lead to a short and therefore the possibility of a fire.

I'd be interested in any comments please.

[RLWP]

I was with a marine engineer yesterday whilst he was conducting a survey for a possible purchase of a narrowboat. During the survey he pointed out that the insulation was polystyrene which apparently causes reaction to plastic electric wiring sheathing. Over time he said the sheathing becomes brittle and thus could lead to a short and therefore the possibility of a fire.

I'd be interested in any comments please.

 

Yes, it does apparently. That is if the wiring is in contact with the polystyrene and not in it's own trunking of course

 

Richard

[Chertsey]

It is well known in boating circles that this is the case and wiring should be run in conduit where there is a possibility of it coming into contact with polystyrene insulation. On the other hand, talking to a domestic electrician, he had never heard of this.

 

Polystyrene tends to be underrated as an insulation material. I've had two boats that used it and both were exceptionally warm and dry.

[Idunhoe]

I was speaking to a fire officer recently and he was certain that one of the main contributors to serious boat fires of recent years is the safety scheme's insistence on so much ventilation. In the event of a fire it is impossible to restrict the flow of air to the fire thus making a very bad situation even worse.

[Sunset Rising]

I was speaking to a fire officer recently and he was certain that one of the main contributors to serious boat fires of recent years is the safety scheme's insistence on so much ventilation. In the event of a fire it is impossible to restrict the flow of air to the fire thus making a very bad situation even worse.

Mmmm. Burn or suffocate, which would I prefer ?

[Robbo]

I was speaking to a fire officer recently and he was certain that one of the main contributors to serious boat fires of recent years is the safety scheme's insistence on so much ventilation. In the event of a fire it is impossible to restrict the flow of air to the fire thus making a very bad situation even worse.

 

Doesn't low ventilation increase the likelihood of carbon monoxide poisoning?

[Keeping Up]

Unfortunately not all boat builders knew about this effect - although it is probably almost universally-known now - so a great many boats were built with the wiring in contact with poly insulation. even some top-quality builders got it wrong; our own, built by Stoke on Trent Boatbuilders, is an example.

 

After many years the wiring had eaten away the poly and sunk into it, but the electrical insulation was thankfully almost unaffected. I was able to rectify the situation fairly easy by creating conduit in-situ, by sliding lengths of garden hosepipe over the wires from one end.

 

A top tip if you do this, make sure the hose isn't an old one that has been lying around in the garden and has a load of soil with baby worms in it; otherwise you get worms dropping out of the ceiling for a couple of years

[MikeV]

Polystyrene tends to be underrated as an insulation material. I've had two boats that used it and both were exceptionally warm and dry.

Agreed, although I don't think you'd find anyone using it on new builds today. As with other insulation types it is important it is well bonded to the steel.

 

We've got a 12 year old boat with polystyrene insulation and a dark blue roof which can get really hot outside, but the internal roof lining barely gets warm. Far more heat gets into the boat from the sun shining through the windows.

 

Our cabling runs inside some kind of flat polythene tubing. It's soft, not rigid, but keeps the cabling from coming into contact with the polystyrene.

Edited July 22, 2011 by MikeV

[WotEver]

... otherwise you get worms dropping out of the ceiling for a couple of years

And you know this because... ?

 

Tony

[blackrose]

Polystyrene tends to be underrated as an insulation material. I've had two boats that used it and both were exceptionally warm and dry.

 

I don't think expanded polystyrene is underrated - it's just that it's been superseded as an insulation material by expanded polyurethane.

[steve hayes]

Agreed, although I don't think you'd find anyone using it on new builds today.

 

When we pass Alverchurch I have often seen polystyrene sheets being fitted to the hire boats being fitted out.

[blackrose]

When we pass Alverchurch I have often seen polystyrene sheets being fitted to the hire boats being fitted out.

 

Are you sure they're not PU sheets? I've no doubt some people are still using PS and I suppose hire boat companies might use an inferior material due to lower cost and their boats mainly being used in the warmer months.

[Robin2]

What's the yellow spray-foam insulation made from?

[alan_fincher]

When we pass Alverchurch I have often seen polystyrene sheets being fitted to the hire boats being fitted out.

It was not that long ago we had a private boat build details on here that used polystyrene sheet insulation, either.

[Chertsey]

What's the yellow spray-foam insulation made from?

Polyurethene I think.

[BlueStringPudding]

Black Prince, I can say from experience, separated the cabling from the polystyrene using parcel tape!

[Radiomariner]

Post deleted

Edited July 22, 2011 by Radiomariner

[hawkers]

Thanks for all your input, so let me pose the question.

Would you buy a boat with polystyrene insulation where as far as you can see the electric wiring cable is not protected with some sort of sheath?

[rjasmith]

Polyurethene I think.

 

Yes definitely polyurethane and there are various grades of it having different degrees of fire retardance and rates of expansion while being sprayed. The usual stuff sprayed on in boats is fairly fast expanding but doesn't build too high whereas the stuff generally available in DIY aerosols is the other way round.

 

I've experienced cables in polystyrene at my son's house so another builder must have been unaware of the problem!

 

What a mess - we had to pull out quite a lot of horrible sticky cable where the PS insulation had depolymerised on to it. As Alan says above though the cable itself seemed to be OK . Nevertheless we replaced both the insulation (in a garage) and the cables.

 

Richard

[nb Innisfree]

IMO it's el cheapo bad practice not to run cabling in a dedicated trunking no matter what type of inslation.

[Theo]

Agreed, although I don't think you'd find anyone using it on new builds today. As with other insulation types it is important it is well bonded to the steel.

 

We've got a 12 year old boat with polystyrene insulation and a dark blue roof which can get really hot outside, but the internal roof lining barely gets warm. Far more heat gets into the boat from the sun shining through the windows.

 

Our cabling runs inside some kind of flat polythene tubing. It's soft, not rigid, but keeps the cabling from coming into contact with the polystyrene.

 

Doesn't that mean that the flat polythene tubing then rots instead of the ploythene insulation on the cables?

 

Nick

[rjasmith]

Doesn't that mean that the flat polythene tubing then rots instead of the ploythene insulation on the cables?

 

Nick

 

No - it's only PVC that reacts with Polystyrene. Polythene is about the most unreactive plastic available - I can't think of anything that will act as a solvent for it.

 

Quite a few other plastics are safe with PS eg the ABS that most trunking is made of. Also of course Polyurethane is quite safe with PVC but as others have said, I'd still use trunking or conduit for all sorts of other reasons!

 

Richard

[RLWP]

Thanks for all your input, so let me pose the question.

Would you buy a boat with polystyrene insulation where as far as you can see the electric wiring cable is not protected with some sort of sheath?

 

We did

 

Richard

[dor]

My previous boat had PS insulkation and all the 12V wiring was done in standard PVC T&E.

It was about 20 years old when I sold it and although there was no barrier between the T&E and the PS insulation I didn't come across any evidence of either the PVC or the PS suffering.

[RLWP]

My previous boat had PS insulkation and all the 12V wiring was done in standard PVC T&E.

It was about 20 years old when I sold it and although there was no barrier between the T&E and the PS insulation I didn't come across any evidence of either the PVC or the PS suffering.

 

Likewise

 

Richard