# EHU cable giving reverse polarity warning



## 4maddogs (May 4, 2010)

I tried to use my old cable (from my 1994 A/S Harmony) to hook up at home (so I can leave the new one in the van) but it put the RP warning light on. When I used the new cable that came with the new van all works fine. 

I presume the old van had a different system? Any (not too complicated) info welcome!

I was going to cut down the old cable to make a shorter length for home use,. Will I need to buy new plugs? The new ones are all blue, but the old ones are blue and white (if that is relevant).
Is it cheaper to buy a new shorter EHU?

Thanks


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## DTPCHEMICALS (Jul 24, 2006)

Change the live and neutral wires at one end of your EHU.


Dave p


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## peribro (Sep 6, 2009)

DTPCHEMICALS said:


> Change the live and neutral wires at one end of your EHU.


.....after checking that they were the "wrong" way round in the first place and that there isn't a wiring fault at either end or within the cable itself that could be causing it. If the cable and plugs are 16 years old and you can't see what the cause of the problem is, then I would be inclined to ditch the cable and find another use for it.


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## DTPCHEMICALS (Jul 24, 2006)

Just slapped my wrists.
Forgot to mention the obvious.

Dave p


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## 4maddogs (May 4, 2010)

The cable worked OK with the old van and seems in good condition. 
Anyone know if the old van (Talbot Express Autosleeper Harmony) used a reverse polarity?
If so I can swap the live and neutral wires.
If not, then the cable must have developed a fault and I will chuck it for safety's sake


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## Zebedee (Oct 3, 2007)

Just do a continuity check on each wire in turn and you will soon see if the cable has been wired up wrongly. (You can use a bulb and battery for this if you don't have a meter.)

If the wires are reversed, just swap the live and neutral at the "wrong" end.

You will also then have checked the earth, which is far more important than reversed polarity.

Finally, if it has been wired the wrong way round for 16 years - why start worrying now?

Dave


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## sideways (Jun 2, 2008)

Its possible the Talbot didnt warn you of reversed polarity and its been reversed all along.


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## 4maddogs (May 4, 2010)

The Talbot was quite basic!

Think that could have been the answer, but it worked OK on the Talbot.....just won't work on the Swift.
Think I will chuck it anyway to be safe.


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## Zebedee (Oct 3, 2007)

4maddogs said:


> Think I will chuck it anyway to be safe.


I wouldn't! 8O

A new one is 30 quid or more. :roll:

Wait until you are on a campsite (or one of our rallies :wink: ) and ask someone to check it for you if you are not confident to do it yourself. A lot of M/Hers carry a meter.

Or take it to your local electrical shop and ask them.

Dave


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## sideways (Jun 2, 2008)

It will be wired incorrectly take the plugs apart at each end and compare them, people have different ideas about reversed polarity if it is wired wrongly it has worked ok all that time. It will be simple just to swop 2 wires at one end. I personally use a polarity checker my mate who travels with me just laughs at me.


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