Ohms are a problem!

Morganic · Jan 30, 2014

Not sure this is correct forum for caravans.
Just had my caravan serviced. MCEA engineer raised problem with 240v system in that ohm reading on earth at sockets was 10 when it should be 0.5. He maintains this is unsafe.
Not been able to say why there is this discrepancy.
Has anyone any ideas. I think it could be due to corroded terminals on hook up socket or on earth connection to chassis.
No other tester has raised this problem and caravan hasn't been used since testing last year
hope someone can point me in right direction please.

itselectric · Jan 30, 2014

Was this done with a meter with caravan plugged into mains

itselectric · Jan 30, 2014

My reason for asking in post 2, is the lead you normally would have to connect your caravan to the mains is 2.5 3 core and is 25 metres long and if he was doing what is called a Zs then he could get a reading like that, That's why caravans are fitted with RCD's (Safety earth trips)

UNG · Jan 31, 2014

itselectric said:
My reason for asking in post 2, is the lead you normally would have to connect your caravan to the mains is 2.5 3 core and is 25 metres long and if he was doing what is called a Zs then he could get a reading like that, That's why caravans are fitted with RCD's (Safety earth trips)

Has he tested the hook up lead on it's own or is he testing from a socket in the caravan, did he check the socket the hook up lead was plugged into to rule out a fault on the installation it was connected to. Having advised you of this problem did he take any steps to locate the problem

I think you need to check the hook up lead for end to end continuity and if possible do an IR check between cores if the lead has had a lot of use and started to break at the cord grips or the colour has faded due to a lot UV exposure it may need replacing, a mate of mine who is a caravan engineer finds a lot of hook up leads fail when tested

telectrix · Jan 31, 2014

surprised no-one has mentioned...... and what if the supply is TT?

Guest111 · Jan 31, 2014

Especially if you are one of the people who sleep in doorways because they are ohmless.sorry I couldn't resist.

sparky6078 · Jan 31, 2014

Does he mean the to a ring continuity? I so sounds like a loose connection

UNG · Jan 31, 2014

sparky6078 said:
Does he mean the to a ring continuity? I so sounds like a loose connection

Caravans are all radial circuits can't remember seeing one with a ring

sparky6078 · Jan 31, 2014

still could be an r2 reading

HandySparks · Jan 31, 2014

sparky6078 said:
still could be an r2 reading

Eh? Can't have an r2 reading if the circuit's not a ring. You will, of course, have an R2 reading.

sparky6078 · Jan 31, 2014

Earth continuity then!!!!!

Morganic · Feb 4, 2014

UNG said:
Has he tested the hook up lead on it's own or is he testing from a socket in the caravan, did he check the socket the hook up lead was plugged into to rule out a fault on the installation it was connected to. Having advised you of this problem did he take any steps to locate the problem

I think you need to check the hook up lead for end to end continuity and if possible do an IR check between cores if the lead has had a lot of use and started to break at the cord grips or the colour has faded due to a lot UV exposure it may need replacing, a mate of mine who is a caravan engineer finds a lot of hook up leads fail when tested

Thanks. I have raised the points you have highlighted with him. He has said that he tested the continuity using a hook up lead. So I have asked him as per your suggestion to check that out. Then he is going to check the continuity in the van system from inlet socket to three pin sockets. Two of the sockets are new.
I suspect the problem lies as you say in hook up lead or at the inlet socket which can be exposed to dirt and moisture and may have corroded pins.
thanks again

UNG · Feb 4, 2014

Morganic said:
Thanks. I have raised the points you have highlighted with him. He has said that he tested the continuity using a hook up lead.

Is he mixing up continuity with earth impedance. He is using a hook up lead but is it your hook up lead or one he has on his van

Morganic said:
So I have asked him as per your suggestion to check that out. Then he is going to check the continuity in the van system from inlet socket to three pin sockets. Two of the sockets are new.
I suspect the problem lies as you say in hook up lead or at the inlet socket which can be exposed to dirt and moisture and may have corroded pins.
thanks again

Could be a loose connection on the mains inlet or a poor connection on the mains distribution unit in the caravan there are a lot of connections / connectors in a caravan electrical system that can give problems. The electrical courses that the caravan industry run are somewhat lacking in content and you may be better speaking to a local electrician who is able to interpret the meter readings and locate the fault if there is one or put your mind at rest