214V domestic supply

[a-z electrics]

Hi All,
Got called out to assess burst water pipe flood damage to ceiling lights but in the course of conversation the client (renting a cottage annexe) mentioned that the hot water supplied from immersion heater for a long time hasn't been very hot. Oh I thought probably the thermostat, so I checked the immersion wiring and found supply to be 208volts. After more chat discovered electric shower only produced warm water too, and freezer not very cold!
Checked incoming at fusebox .. the same 208v.
Checked incoming at local meter, the same. Checked source fuse box in main house, this was 214 volts. Checked first meter supplied direct from meter head, this also 214V.
Conclusion.. undervoltage supply.
Western power had put in an additional supply cable last summer, might be a coincidence?
I checked tester when I got home and my supply a healthy 240v. I have to produce a report for the landlord..

Anyone else had a similar problem?
The landlord, who lives in the main house commented his leccy bills have drastically increased the last few months.. could this be attributed to the low voltage?

 

[Lucien Nunes]

The landlord, who lives in the main house commented his leccy bills have drastically increased the last few months.. could this be attributed to the low voltage?

Unlikely. Some loads consume constant power as the voltage falls, by taking higher current to compensate. Others the power falls with the voltage, if they are resistive then it falls with the square of the voltage. A 2kW 230V electric heater will consume only 1730W at 214V. However, if it is thermostatically controlled, it will run for a greater duty cycle and consume as much as it would have done at 230V over a period of time.

Therefore, some loads will be reduced and others equal, only a few minor losses will increase. However, if someone was running a horticultural operation off the supply, their heavy load might increase both the bills and the voltage drop...

 

[Risteard]

It could be a loose connection causing excessive voltage drop rather than a low supply voltage. If you are certain that the problem is external then you should contact the DNO. This is all assuming that your voltage measurements are accurate.

 

[marconi]

I wonder if there is an L-E fault in the cable supplying the annexe. It would be a good idea to do some residual current checks on the LN feeds at the main house to see if current is flowing to terra firma. This could possibly explain the higher electricity bills. You can also look at the main house meter and see how quickly it is clocking up the units when all final circuits in the main house and annexe are turned off; and perhaps then turned on individually to see if there is a problem on one of the final circuits (assuming they have no RCD protection of course).

Then if you can do some IR on the cable between the main house and annexe.

You get the gist....

What is the earthing system in each dwelling?

 

[a-z electrics]

There are 6 DBs in main house and 1 in annex, which is about 15 metres away. All apart from 2 I think in the main house are RCD protected. The annex is fed via a fuse box which is Tee,d off the house supply. Tncs earthing on main house.
I have to confess I didn't have my main MF tester with me and I took volts reading with probes but I checked them at home ok when I got back.. I have also installed various DBs at this property in the past including the annexe and done Periodicals without any untoward results but I take your point about loose connection and volts drop. It isn't a straightforward property and also has solar PV panels just to complicate matters.. I shall need to return next week.

 

[a-z electrics]

Actually the problem wouldn't be loose connection or volts drop downstream if the supply virtually at the source is at the reduced voltage would it? Earth leakage a possibility though as there is no overall rcd on the Installation..

 

[Deleted member 105166]

Suggest to your client to report the under-voltage to the DNO. When it is outside the permitted voltage of 216V-253V - Appendix 2 (14) , in my experience they react and rectify quickly.
I monitored a recurring over-voltage up to 257V on a supply recently, told SSE about it and within 24hrs they visited and installed a recorder for 3 days, subsequently agreeing with the data I'd given them and tapped down the supply at the transformer.

 

[marconi]

This is an interesting problem so we'd like to keep up to date on it please. Must go now and attend to my hasselback potatoes - after electricity I love cooking.

 

[Risteard]

Actually the problem wouldn't be loose connection or volts drop downstream if the supply virtually at the source is at the reduced voltage would it?

There could be a loose connection in the meter, however, for example, or minipillar or whatever.

 

[static zap]

Was there a meter at annex end BD/CU .
(no obvious signs of stress that end?)

 

[a-z electrics]

Was there a meter at annex end BD/CU .
(no obvious signs of stress that end?)

There was..and I checked each side plus screen tightness..

 

[a-z electrics]

Sorry .SCREWS tightness...

 

[a-z electrics]

There was a meter but I tested both sides of it and checked tightness of the screws..

Thanks for all your replies.. i shall return next week with an earth leakage clamp.
I suspect either Western power did something when they put the new line in or there is an earth leakage which may explain the high bills..

 

[static zap]

Bill could be a red herring - cold season/different tennant? ,
(keep an eye for melted snow if underground cable ! )

 

[Dave OCD]

Possibly there was an exceptional demand in the local area due to the freezing weather at the time of the voltage being measured or it could be a connection failing externally, particularly if the supply is overhead.