Supply Voltage?

[markocosic]

Finished with the CU replacement (dead RCD/whole new board cost less than replacement...) and whilst checking various voltages (courtesy of a poxy dead-from-new MCB) I checked the incoming supply.

Domestic supply - 20 years old, single phase with 60A fuse, 40A rated meter and 16mm^2 meter tails.

Supply at the isloator switch to the house under no load - 218V

Supply at the farthest socket whilst hanging a 3kW kettle off it (in the deepest darkest corner under the big scary cheese plant... ) - 215V

Should it not be nearer 230V under load? (thinking that the lighting would appreciate the difference disproportionately) Will the electric board do anything about this, and would it be their tab or mine?

 

[ColJack]

theirs..

though by regs they are currently allowed to go as low as 216.2 volts.. proposed to change in january to 207v...


your lights will last longer at the reduced voltage though..

and I hope you notified the LABC... board changes are notifiably under part P...

FULL test and inspect required..

 

[djrichie_t]

You are permitted to have this changed to a 100 amp cut-out fuse, and an new meter, free of charge.

When things changed to 230 volts... all that really got changed was the paperwork (as we just couldnt be doing with going round all the substations changing the transformer tappings to satisfy the EU) - So we authorised the tolerance to be 230v +10 and -6% and the IEE had to accept it wether they liked it or not.

However, electricity companies will still stick to the old rules of 240v +/-6% so if your off load volts starts to drop below 220v they will sort it, and yes its their tab!

The reason for this is that where consumers use more and more electricity, the first little sign of a cable fault can be low volts, and normally the first thing to burn off is the neutral, meaning floating neutrals which is not good at all! TT or TNS systems will be the ones that can suffer, as newer systems are neutral/earth combined, hence PME.

Also it is recommended to have 25mm tails from the cutout to the meter and onto the CU.

 

[jossper]

You have to be careful taking measurements of AC voltages with multimeters. Most older/analogue meters (such as AVO 8s) are calibrated to read average voltage which is 0.636 of peak. Mains voltage is quoted as RMS which is 0.707 of peak. Unless your meter is labelled as something like "true RMS" or is one aimed at electricians I would suspect it is calibrated to read average and this is why you have a low reading.

Your 218V, if it is average, works out to 242Volts RMS

Paul

 

[ban-all-sheds]

When things changed to 230 volts... all that really got changed was the paperwork (as we just couldnt be doing with going round all the substations changing the transformer tappings to satisfy the EU)

It's absolutely nothing to do with the EU - voltage harmonisation is a CENELEC project, and CENELEC comprises 30 member countries, not all of which are in the EU.

So we authorised the tolerance to be 230v +10 and -6% and the IEE had to accept it wether they liked it or not.

It's absolutely nothing to do with the IEE - CENELEC members are national organisations entrusted with electrotechnical standardisation, and the UK organisation is the British Electrotechnical Committee, which is part of the BSI.

Why do you just assume that an internationally agreed change has to be something which has been forced onto us against our will by the EU?

Tolerance levels were originally supposed to go to ±10% in 2003, then 2005, and then 2008, but that was agreed in July 2001. Does anybody know if we're still on for the 2008 date?

 

[Stoday]

When things changed to 230 volts... all that really got changed was the paperwork (as we just couldnt be doing with going round all the substations changing the transformer tappings to satisfy the EU) -

Electricity distribution engineers set distribution transformer taps to achieve a no-load output of the statutory maximum voltage. 20 years or so ago when the declared voltage was 240V +or- 6%, this was 254V. Now it is 253V. As both are practically the same, the transformers were already on the correct tap.

The advantage to DNOs is the permissible volt drop over the distribution feeders is increased by 33%. I can believe that some DNOs will alter links on the LV network to maintain voltages better then the minimum permitted, but I don't believe that many would spend money overlaying cables unless thay had to.

 

[markocosic]

Good call - the meters are an Iso-Tech IDM66 (RS 216-766) and a Siemens B1022 (RS 653-086). Don't have instructions for either - anybody know if they're reading RMS for AC?

Free 100 amp might prove handy though, thanks for the tip. Will wait to see what SWMBO (she who must be obeyed...) eventually decides in the kitchen. For the minute the house is gas everything (gas hob, gas oven, gas heating, gas water/showers) so 60 amp and the 16mm tails is fine for the lights, TV and PC etc - but I know that she wants at least an electric oven (ok with supply as is) but if she finds a nice induction hob as well then that'll want the 100 amp supply and 25mm tails.

Part P? Much as I'd love to tell an unqualified civil servant (LABC) to naff off and get a qualified spark in instead (see previous posts) in this instance it ain't worth the risk of no payout on house insurance in the event of fire etc.

Easy enough to comply with, but totally ineffectual.

 

[ban-all-sheds]

Part P? Much as I'd love to tell an unqualified civil servant (LABC) to naff off and get a qualified spark in instead (see previous posts) in this instance it ain't worth the risk of no payout on house insurance in the event of fire etc.

¿Que?

If you use a registered electrician, in what way would your LABC be involved?

 

[ColJack]

where does he say he's registered?

 

[markocosic]

If you use a registered electrician, in what way would your LABC be involved?

DIY job.

Back in the day I'd do the work myself and have an experienced spark do a quick sanity check.

These days I can do the work myself, but rather than having an experienced spark look at it you have to get the LABC in instead.

It'd be great - if the LABC actually had a clue...

 

[tim west]

though by regs they are currently allowed to go as low as 216.2 volts.. proposed to change in january to 207v...


your lights will last longer at the reduced voltage though..

Not if they are Halogens

 

[ban-all-sheds]

Back in the day I'd do the work myself and have an experienced spark do a quick sanity check.

These days I can do the work myself, but rather than having an experienced spark look at it you have to get the LABC in instead.

I see what you mean.

It'd be great - if the LABC actually had a clue...

If you've paid them for a service, don't let them get away without providing it...

 

[markocosic]

They provide the service all right - they hire the same bloke to come and sanity check that I would... (but charge more for the pleasure of keeping an otherwise unemployable middleman in business)

 

[Jim2287]

40 Amp rated Meter and higher rated fuse is apparently a permitted thing by electricity board ... we rang up several times in the past and they said its fine ...guess its really rated higher