L

LlandrilloSpark

I went to a customer today who told me she had a pre electrical survey done by BG before they would agree to connect a new boiler, the "survey" was done by the sales guy.

Basically she told me that he said BG would not connect the boiler because he did a "socket and see test and he got more than 100 ohms???",he didnt remove any loads or isolate anything whilst doing this test, after getting this reading he promptly went outside looking for an earth rod.

If the guy had the common sense to actually look in the right meter box(he looked in the gas meter box), he would of noticed the supply is a TNCS which was installed in 2001, 35mm tails from the road, 25mm going through the outer walls and into the basement.

I carried out a Zs test on each floor of the house, the results were 2.16ohm, 2.01ohm,1.95ohm and 1.98 ohm all on 32A mcb's, all 3 circuits exceed the OSG max permitted figures,

I then took 5 Ze readings, they varied from 1.05ohm - 1.15ohm so its fair to say its the high Ze which is the problem.

The installation is protected by a 30ma RCD Main Switch, so perhaps this problem was spotted earlier.

I tested the RCD fully and the times come back 17.8ms(x1) and 7.8(x5)

My query is should or can British Gas refuse to connect the boiler to a circuit which is protected by a fully working RCD, when the Zs is averaging 2ohms when the advice the IEE gives to us is that we can safely use circuits on RCD's when the loop well exceeds 21ohms or more.

I have to write a report for the customer and also advice on contacting the DNO so i'd appreciate your valued feedback!!

Cheers
 
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had similar. high Zs was due to the RCD. proved by having a Ze of 0.2, and measuring on the load side of the RCD got 349.
 
I'm planning to use the equation R1+R2=Zs-Ze to prove that the inernal loop on the consumers side is healthy, can anybody see any issues with this?!!
 
sounds fine, but the Ze needs to be addressed by DNO as the max. is 0.35 and they have an obligation to maintain this.
 
There is obviously a problem for the DNO if the Ze on on a PME supply is over 1 Ohm but as there is a 30mA 'front end' RCD in place, the disconnection times are met by that.

Now try explaining that to the BG chap who will have a sheet saying that if the 'Ze' is over a certain amount then there should be an earth electrode-no electrode, go back to the van and drive away.

Your report should mention that there is a supplier earth problem but that the safety issue is negated by the RCD (assuming it disconnects according to whatever BS it is).

British Gas can of course stipulate any connection criteria they like but it doesn't mean that the decision will be correct.
 
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The report will contain all of the above and in draughting a letter to the DNO for her, I hope it works as they need new boiler for The winter.Does my head in that a BG salesman can carry his "ohmmeter" as he called it in his bag and make assumptions on someones installation
 
The report will contain all of the above and in draughting a letter to the DNO for her, I hope it works as they need new boiler for The winter.Does my head in that a BG salesman can carry his "ohmmeter" as he called it in his bag and make assumptions on someones installation

You've never lived 'til you've had the 'gas engineer' telling you to 'cross bond' the boiler pipework or that the Zs of 5.3 Ohms at the boiler spur on an RCD protected TT system is dangerous!
 
as i know f*** all about gas, perhaps i can buy a manometer and start testing gas systems. it's all a plot to get people to convert back to gas lighting.
 
as i know f*** all about gas, perhaps i can buy a manometer and start testing gas systems. it's all a plot to get people to convert back to gas lighting.

Piece of pi$$ Tel ....... it's 1 minute @ 10 Mbar to check that the Emergency Control Valve isn't letting by, followed by 2 minutes @ 20 Mbar to allow for Temperature Stabilisation, then a further 2 minutes @ 20 Mbar for the actual test.

If the installation is new, then no drop is allowed. A certain drop is allowed (check the tables in the book) for older installations.

Anybody can do it !! ;)
 
I'd tell the customer to go to someone other than BG to get a new boiler. They are really expensive.
**My mate is a gas fitter, and can easily beat BG's quotes by up to £1k. I was wiring one up for him recently, a straight combi swap, he had been there for 6 hours, and charged £1500. he was a bit coy about what he was making, but I got the impression it was around £500 profit - he said BG had quoted £2300 for exactly the same as he was doing, and their service level was worse than his, if he gets a call about a fault, he goes out without fail that day, BG you go to a call centre and get a call when they can fit you in.
 
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I'd tell the customer to go to someone other than BG to get a new boiler. They are really expensive.
*My mate is a gas fitter, and can easily beat BG's quotes by up to £1k. I was wiring one up for him recently, a straight combi swap, he had been there for 6 hours, and charged £1500. he was a bit coy about what he was making, but I got the impression it was around £500 profit - he said BG had quoted £2300 for exactly the same as he was doing, and their service lever was worse than his, if he gets a call about a fault, he goes out without fail that day, BG you go to a call centre and get a call when they can fit you in.

I agree.

I used to subby for them until I got sick of their rip-off practices & told them to shove it.
 
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British Gas refusing to connect
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