Low voltage - less than 190v some days.

[mattysupra]

Hi, Just after some advice.

I have a boat that i retire to at the weekends. Its kept at a boat club rather than a Marina. (Same sort of set up)

The problem im having and the rest of the boat owners is we are getting less than 190volts out the sockets on the boats.

Summer time we still have low voltage but normally its over 200volts. I guess the extra drain of heaters over winter are the reason why it gets lower.

The Question, does the electric board HAVE to supply a certain voltage? Do they legally have to supply a certain amount of power?

Thanks

 

[westie101]

The requirement is to maintain 230V +10% or - 6% at the meter position, if this is being met, the rest is the responsibility of the boat club if that is where you are moored.

 

[JohnW2]

I have a boat that i retire to at the weekends. Its kept at a boat club rather than a Marina. (Same sort of set up) ... The problem im having and the rest of the boat owners is we are getting less than 190volts out the sockets on the boats. ... Summer time we still have low voltage but normally its over 200 volts. I guess the extra drain of heaters over winter are the reason why it gets lower. ... The Question, does the electric board HAVE to supply a certain voltage? Do they legally have to supply a certain amount of power?

Yes - they are not allowed to let the supply go more than 6% below the nominal 230V (which works out as 216.2V) for significant proportion of the time (IIRC, they are allowed 5% of the time).

However, that's in terms of what they supply to the origin of the consumer's installation. It therefore could be that the boat club is getting a satisfactory/'legal' voltage, but their own distribution circuits (to the sockets) are inadequate, leading to voltage drops before it gets to the boats. Are their long distances involved?

Someone needs to measure the voltage near to the 'origin' of the boat club's installation (i.e. where they 'receive' their electricity) at a time when the sockets are getting only a low voltage.

Kind Regards, John

 

[OwainDIYer]

The electricity supplier (DNO) has to supply between 230V +10%/ -6%, or 216.2V to 253v as stated in the Electricity Safety, Quality & Continuity Regs (ESQCR) (unless it's changed again).

However you are probably not buying electricity from a DNO but from the boatyard operator. I don't know if they're subject to the same requirements.

Poor voltage regulation may be a sign of a poor quality connection in the service intake or submains and this could overheat and cause a fire.

 

[mattysupra]

Ok, thankyou

So we need to monitor what the supply is at the main meter ( leaving the main meter) then?

If that is ABOVE 216.2v just after the meter and the volts are low at boats then thats the marinas problem to sort ?

If BELOW 216.2v then the electric board have to sort out ?

If it is not enough power coming in to the first meter and it turns out to be the cable size coming in is to small, who has to pay for that? I presume if its the transformer (50 meters away) then they pay for cost to upgrade it ? but what able cables?

 

[westie101]

If BELOW 216.2v then the electric board have to sort out ?

If it is not enough power coming in to the first meter and it turns out to be the cable size coming in is to small, who has to pay for that? I presume if its the transformer (50 meters away) then they pay for cost to upgrade it ? but what able cables?

However if the boat club has increased the demand over and above what is authorised it will fall to them to cover the costs of upgrading it.

Certainly in a case such as this as well as checking the voltage over 7 days I would be checking the load as well to see if it is within authorised limits or DNO equipment is being overloaded.

 

[mattysupra]

If BELOW 216.2v then the electric board have to sort out ?

If it is not enough power coming in to the first meter and it turns out to be the cable size coming in is to small, who has to pay for that? I presume if its the transformer (50 meters away) then they pay for cost to upgrade it ? but what able cables?

However if the boat club has increased the demand over and above what is authorised it will fall to them to cover the costs of upgrading it.

Certainly in a case such as this as well as checking the voltage over 7 days I would be checking the load as well to see if it is within authorised limits or DNO equipment is being overloaded.

This is what i was thinking. The demand has defo gone up over the years as the boats have become more modern with more electrical gadgets attached to them.

For example, when i first arrived i plugged in and the breaker kept tripping. It was upgraded from a 6amp to a 10 amp. Obviously the boat in my place before i arrived was fine on a 6 amp breaker. My boat requires more power.

How do you find out the above with what your allowed etc?

 

[westie101]

Interesting, so the moorings were probably designed for 6A supplies and over the years some/all/most have been uprated to 10A
That in itself will hugely increase the load and thus the volt drop on the wiring system
If you are not suffering sudden power cuts by blowing fuses & MCBs at the meter position (or even the DNO main fuse) it sounds as though it could be more on the wiring and excessive volt drop

 

[westie101]

As for what load is allowed that will be possibly in the paperwork from when the supply was first installed.
If not as a rough rule of thumb if the meters are wired directly to the cut-out for single phase around 20kW and for 3 phase around 60kW
Without looking it is hard to tell.

In the first instance as suggested get the voltage checked next to the meter position when the boats have low voltage, If it is OK get an electrician involved to check the wiring design.
If it is out of limits or well below 230V report it to the DNO

 

[mattysupra]

Interesting, so the moorings were probably designed for 6A supplies and over the years some/all/most have been uprated to 10A
That in itself will hugely increase the load and thus the volt drop on the wiring system
If you are not suffering sudden power cuts by blowing fuses & MCBs at the meter position (or even the DNO main fuse) it sounds as though it could be more on the wiring and excessive volt drop

I know that the DNO ?? have been contacted a few times but they never come out to check or phone back like they say.

So what would be the best way to monitor the power?

 

[ericmark]

I also had this problem with a caravan and a narrow boat. When the site owner was approached in both cases the same answer "OK I will just have to stop supplying power" and although when supplying power there are rules there is nothing to say they must supply power.

The cure was to use switch mode battery chargers and inverters on the boat. It really did not matter if the voltage dropped to 160 volt the switched mode battery charger still charged the battery at 25 amp and the inverter still gave 230 volt output from the batteries.

The oil filled heater did not care if 150 volt or 250 volt the thermostat still controlled it. So that was direct onto the supply.

Where there was a problem was with the site owner. Although the meter is suppose to meter in kWh in fact it metered amps. So when the volts dropped he got charged over the top as charged amps per hour even though the meter said watts per hour.

He contacted the DNO and they agreed on a rebate. In my case with caravan the site had a temporary licence during the building of Sizewell 'B' power station had it been a long term problem I am sure the DNO would have fitted a larger transformer.

Going to site owners or DNO guns blazing is clearly not the way around the problem. It's a case of WE have a problem how are WE going to get around it.

With the caravan site he provided each caravan with a 6A MCB supplying power but caravan owners were opening up the supply boxes and swapping the 6 amp to a 16 amp and scratching off the 1 or moving the adjustment screw (Old Loadmaster MCB's) either way they were using more than the agreed amount of power.

You may have some thing similar the site owner got a 2 kW fan heater and plugged it into each outlet if it did not trip he swapped the MCB and put it in a locked box so if it tripped the caravan user has to ask him to reset rather than being a DIY job. He would delay resetting as he knew very well the caravan guy had been cheating him of power. He also charged the caravan user the cost of MCB replacement any arguments he would offer to bring in the police.

In view of this do tread carefully you don't want to upset the apple cart. I have seen it all before.

 

[mattysupra]

Hi Eric,

I wont be upsetting the apple cart or demanding they fix the issue etc

Where i keep the boat its a 'Club' where we all knock in together to help maintain the place, any works we try and do ourselves on "working weekends" where every one turns up and helps with maintenance.

If its out of our hands we obviously call in someone qualified etc. But we would pull in new cables for example ready for the sparky to connect up.

We all want the issue of low electric fixed, more so the new boats that have a microwave for example over the old school gas cookers. The microwaves wont start up so we all end up running our generators when using the microwave.

Any upgrades wont cost anyone personally as the club will pay the bill. but the more money we can save the club the better as the money can be used else where on better facility's etc.

 

[ericmark]

So we start with 230 v +10/-6% = 253 - 216.2 volt at the DNO head for power you are allowed a further 5% and lighting a further 3% so 205.39 or 209.714 depending if power or lighting supply. I seem to remember there are some time limits as well.

So in real terms an appliance should work at 205 - 253 volt if it does not work at 205 then down to appliance not the supply.

The volt drop is simple ohms law so 6mm² cable for example will have a volt drop of 7.3 mV/A/m so a 100 meter run with 10 amp draw will give a volt drop of 7.3 volts.

However the problem is to measure volt drop as walking from one end of the marina to other to take two readings it may have changed anyway so the way to measure is with a loop impedance meter.

These meters have a built in load and by measuring the voltage with and without the load will give an impedance reading directly from the meter. So starting at as close to the DNO supply you take a reading. This tells you the value in ohms of both the cable and the transformer. Typical in a house would be 0.35Ω.

Next is a clamp-on ammeter which will show how much you are drawing so as an example lets say 100A.

Now if the DNO was to set the tapping to give 253 volt no load then simple ohms law you would get 218 volt at the head.

The same method can be used at each outlet to work out what the volt drop should be if no one is cheating.

Step one is to find if the major part of the problem is supply or internal wiring and using a loop impedance meter you can work that out. Clearly if a supply problem then down to talks to DNO. I remember at a factory having talks about increased power requirements and it was about either a second transformer or a larger transformer and we were not charged by the kWh but by maximum demand at set parts of the day. So much would depend on the agreement signed by the club.

If it is volt drop within the club then it needs some careful planning a radial supply could be made into a ring for example by simply running a new cable to the end of the radial.

It may be curable by an agreement which boat cooks at what time.

I was reading on a boating forum about inverters designed to top up top requirements so a boat could have a 4 amp supply and the inverter can supply the extra 6 amp at peak times.

Likely there will be some cost and what the members have to decide is how best to spend their money. May be solar panels are the answer with the grid tie inverter this would clearly boost voltage during the day and reduce bills.

Warning grid tie inverters have safeties to stop them boosting the voltage to over 253 volts and also to switch off when there is a power failure. There will be a lower voltage limit as well as the upper one and once the inverter trips it remains off line for a set time the idea is with a road full of inverters if the supply is removed the inverters will not just sense each other so continue running but will close down likely one at a time and I am not sure of the points where they close down.

 

[OwainDIYer]

However the problem is to measure volt drop as walking from one end of the marina to other to take two readings it may have changed anyway so the way to measure is with a loop impedance meter.

If a loop meter is not to hand, then two voltmeters (calibrated against each other) and simultaneous measurements synchronised by mobile phone may provide a useful indication.

It wouldn't surprise me if the whole installation wasn't running off a 40A DP ironclad cutout in a shed somewhere.

 

[ban-all-sheds]

Just curious - what's with all the blank posts from Mod 11?