Earth continuity test

Purplecoop

Just a question. I have a mynute 14e vokera boiler. I pay scottish power monthly to service it but this year they are telling me the boiler isn't earthed. Do you need to remove the fuse to do the check?


Basically it was a new guy being trained up and he was getting a reading of like 54 ohms. They called someone who said they couldn't work on it. They tried again to get a high reading so they could take a photo for proof. They then found the readings jumping all over the place and said "this meter is ****ed, at least we got a photo of a high reading incase the electrician says it's ok"


Don't think they realised I could hear them and they denied saying that when I brought it up


They then put boiler back together and I heard the guy tell the new guy what to tell me who then came through an repeated it word for word. I asked to see the reading as I didn't understand how it's been fine every year but isn't this year. And he said he couldn't tell me if others have done the checks.

He also said "do you even understand ohms?" Now it's been a while since school but I got an A in advanced higher physics so I did once upon a time. But I pointed out the reading is meant to be under 1 I'm sure it's not hard to look at the meter and read the reading.


Now a quick google brings up a page on boiler fault finder Which says you need to remove the fuse, but they didn't. I'm just wondering does this make a difference? Just before I pay some electrician a fortune to come out and check it.

mikeyjames9

You'll probably have ever to get a REC to check the wiring if they have declined to service boiler

Mod edit: The rest of this post has been deleted to prevent the thread turning into a train wreck.

2011

Purplecoop wrote: »

I pay scottish power monthly to service it but this year they are telling me the boiler isn't earthed. Do you need to remove the fuse to do the check?

No.

Basically it was a new guy being trained up and he was getting a reading of like 54 ohms.

A resistance reading has to be taken between two points.
In this case what are the two points?

I would expect the two points to be between the gas pipe and the MET (main earth terminal) which is located in the distribution board. This test should be carried out using a calibrated test meter and a generally a wander lead is used.

In addition the power supply to the boiler should have a earth (known as the circuit protective conductor). However this is installed for a different purpose.

They called someone who said they couldn't work on it. They tried again to get a high reading so they could take a photo for proof.

A photo would not be considered any kind of proof.
Normally a suitably qualified / trained person carries out this test using professional, calibrated equipment and thier word is considered sufficient.
You do not appear to have employed people that fit that description.

They then found the readings jumping all over the place and said "this meter is ****ed, at least we got a photo of a high reading incase the electrician says it's ok"

Readings such as this can "bounce around" due to "noise" on the earth system. This can be caused by many factors such as the installation being neutralised and small (but safe) levels of current flowing through the earthing system. My concern is that the people carrying out the test do not appear to be confident in the reliability of their meter. From your description the people you employed appear to be confused.

They then put boiler back together and I heard the guy tell the new guy what to tell me who then came through an repeated it word for word. I asked to see the reading as I didn't understand how it's been fine every year but isn't this year. And he said he couldn't tell me if others have done the checks.

Time to call in a qualified electrician in my opinion.

He also said "do you even understand ohms?" Now it's been a while since school but I got an A in advanced higher physics so I did once upon a time. But I pointed out the reading is meant to be under 1 I'm sure it's not hard to look at the meter and read the reading.

An "Ohm" is the SI unit of electrical resistance. A home owner employing the services of a professional to carry out this work should not have to know this.

Purplecoop

A resistance reading has to be taken between two points.
In this case what are the two points?

I would expect the two points to be between the gas pipe and the MET (main earth terminal) which is located in the distribution board. This test should be carried out using a calibrated test meter and a generally a wander lead is used.

The points where the screw on the switch on the wall and the metal casing of the boiler.


It's a big national company. One of the main gas and electricity suppliers. I pay monthly for boiler cover in case it breaks down and this includes a yearly service. This Was them coming out for my yearly service.


I've found out a friend is an electrician so he is going to come and check it out.

I ended up going and buying a multimeter and checking it myself cause I didn't trust the guys that much. But I did get a reading of around 2 to 3 so there does seem to be some issue but whether it's with the boiler or the house. As we don't seem to have a separate earth cable for the house supply. According to our friend. Will get to the bottom of it.

Sir Arthur Daley

Purplecoop wrote: »

The points where the screw on the switch on the wall and the metal casing of the boiler.

I take it you are on about the isolation switch for the boiler, alot of these would only carry the earth to one screw and if switch was mounted on plastic box you would not get an earth off that screw.

2011

Purplecoop wrote: »

The points where the screw on the switch on the wall and the metal casing of the boiler.

This is not the way this measurement should be taken.

Assuming that the test meter is good quality and functioning correctly the fact that a reading of 54Ω suggests that the box is unlikely to be plastic as plastic is nonconductive.
This would result in an infinity reading with most ohm meters.

It's a big national company.

Means nothing.

I've found out a friend is an electrician so he is going to come and check it out.

Good idea.

FYI:
The gas pipe should be bonded with a 10 sq. earth cable. The other end of this cable should be connected to the MET.
The electrical supply to the boiler itself is generally a 4 core cable containing a permanent live, switched live, neutral and an earth (CPC).