Test road lights while connected to EHU

[JB1]

Hi does anyone know if it’s safe to hook the car 13pin 12v connection to the caravan to test the road lights, while the caravan is connected to the 240v EHU.
thanks Jeff

 

[otherclive]

Why would you want to do that when it takes a couple of minutes to disconnect the 240v and reconnect? Is it safe? No idea because it never even occurred to me to do as you suggest.

 

[ProfJohnL]

I must admit I've never considered this point, and I'm pretty certain at some time I have had both the EHU and the car connected at the same time, and I've never had a problem, but I'm not suggesting its the best thing to do.

But knowing the way the wiring should be installed, and provided the wiring has been installed and maintained correctly, then there should be no danger of anything untoward occuring.

Even if there is a fault, the caravans 230Vac mains input protection system should be able to keep you safe.

As I no longer have a caravan, its not an issue for me going forward, but I do think its wise not to invite problems so I suggest avoid doing it.

 

[Dustydog]

A very odd request but why not ask.
I always check my lights last of all when EHU is disconnected and immediately before departure. All part of the hitching up process.
Technically is it possible for a cross connection eg fridge or charger to cause an issue? I don’t know but why take a risk for no tangible reason or purpose. I’m in the NO camp

 

[GaryB]

It's fine, I've just done mine now at home as I have done for the last 25 years. I always hitch up and check the lights well in advance of leaving "just in case" but leave the caravan on mains until leaving to keep the fridge running.

 

[JB1]

Thanks for replies as GaryB has said it just to check the lights in advance rather than last minute and then if there is a problem you are rushing around to sort it out. I like to keep to my schedule 🤣. I do wonder about the fridge and the leisure battery having both the car and battery charger connected ? . I have my caravan on my drive, so I can hook up to the car well in advance of actually leaving. I still keep most of the caravan weight on the jockey wheel with the steadies just touching the ground to save undue stress on the car. Thanks again JeffB

 

[ProfJohnL]

...
Technically is it possible for a cross connection eg fridge or charger to cause an issue?...

I do wonder about the fridge and the leisure battery having both the car and battery charger connected ?

All appliances that are approved to use mains power, should have the necessary separation of low voltage and extra low voltage circuits to meet the required safety standards, so a serious fault would have to arise or it's been installed incorrectly for it to be a problem.

... I still keep most of the caravan weight on the jockey wheel with the steadies just touching the ground to save undue stress on the car. Thanks again JeffB

Whilst you are doing no harm in this practice, but it really isn't necessary. The cars tow hitch is given a Static Nose Load Limit (S value) which might seem quite small, but the reality is the tow bar has to be designed with a substantial excess margin of capability, becasue when in motion the actual nose load can vary very dramatically because of the complex mixture of loads and forces involved when towing. Its quite normal for the dynamic loads can reach and exceed 5 to 8 times the static value and in the most extreme circumstances values over 10 times the static value.

Because it's impractical for normal drivers to measure the dynamic loads, the regulations tell the manufacturer to quote a static value which must take into account the variances caused by actual towing.

Its therefore not a problem exceeding the S value whilst the caravan is hitched up whilst you move around inside, just ensure that when you begin towing the nose load is below the S value.

 

[Buckman]

I would be more concerned about forgetting we are still hooked up to EHU and driving off. We always check the lights after we have moved the caravan.

At the same time when the caravan is straight behind the vehicle I check the towing mirrors. OH at back of caravan indicating lights are working and if I can see her, mirrors are okay.

 

[Lutz]

The road lights are on a completely different circuit to the habitation electrics of the caravan so the one won't affect the other.