House seems low on electrical power

Kieran007

I have a new house and it seems to me that it may be down on power. Lights flicker when I am vacuming, recently a contractor complained his saw (110v via a transformer) was low on power in my house.

I have also noticed the motor in my HRV system powering up and down a little as I switch appliances on and off. None of this seems normal to me.

The unique thing is when building it we put the ESB meter is at the gate, 135meters from the main fuse board in the house. We used SWA 24mm cable. I measured the voltage at a socket using a multimeter and it is 232v.

Is there something else I should measure? Should I be able to test amps? As far as I know the ESB fuse at the meter is a 63Amp supply.

Suggestions and help welcome

sparcocars

Kieran007 wrote: »

I have a new house and it seems to me that it may be down on power. Lights flicker when I am vacuming, recently a contractor complained his saw (110v via a transformer) was low on power in my house.

I have also noticed the motor in my HRV system powering up and down a little as I switch appliances on and off. None of this seems normal to me.

The unique thing is when building it we put the ESB meter is at the gate, 135meters from the main fuse board in the house. We used SWA 24mm cable. I measured the voltage at a socket using a multimeter and it is 232v.

Is there something else I should measure? Should I be able to test amps? As far as I know the ESB fuse at the meter is a 63Amp supply.

Suggestions and help welcome

The cable you used is too small and the voltage is dropping under load. Replacing the cable would be the only thing to do there. A minimum of 50mm square should of been used but even that would be on the volt drop limits outlined in the etci rules. 70mm square or over would of been the best option. You should of still put the meter box at your house and let the esb worry about running the bigger cable to your house but your best option now is probably to replace the cable with a bigger cross sectional area cable.

evosteo

Kieran007 wrote: »

the ESB meter is at the gate, 135meters from the main fuse board

We used SWA 24mm cable.

:eek:

who decided to use that size cable??????

evosteo

more than likely will also need a distribution board upgrade also due to the larger sized cables been terminated

Bruthal

evosteo wrote: »

more than likely will also need a distribution board upgrade also due to the larger sized cables been terminated

I wouldnt think the 70 square would have to be terminated into the DB. It could be terminated into some sort of minipillar and then 16 square brought in the last few meters.

Realistically the meter should be moved to the house, as the meter is probably only supplied with 25 square as well.

M cebee

never came across this setup before

Bruthal

No it seems a bit mad. Hard to believe the ESB connected that setup.

M cebee

if the voltage drop is serious enough

i'd look at bringing a esb service to house first alright

voltage drop is pretty good in rural dom installations these days- with trafos close to houses usuallly

2011

A very rough calculation:

Maximum current: 63A (this is the size of the switch foes for a domestic installation)

Length of run: 135m

Cable type: 3 x 70 sq. mm XPLE/SWA copper conductors

mV/A/m: 0.69 (for 3 x 70 sq. mm XPLE/SWA copper conductors)

Volt drop = (0.69/1000) volts x 63 amps x 135 metres

Volt drop = 5.87 volts which is a 2.55% volt drop = Good



mV/A/m: 1 (for 3 x 50 sq. mm XPLE/SWA copper conductors)

Volt drop = (1/1000) volts x 63 amps x 135 metres

Volt drop = 8.51 volts which is a 3.7% volt drop = Not great




mV/A/m: 1.9 (for 3 x 25 sq. mm XPLE/SWA copper conductors)

Volt drop = (1.9/1000) volts x 63 amps x 135 metres

Volt drop = 16.16 volts which is a 7.03% volt drop = FAIL :eek:

Bruthal

What voltage will a digital mulitmeter show on the cable with no load on it if its 100 miles long?

2011

robbie7730 wrote: »

What voltage will a digital mulitmeter show on the cable with no load on it if its 100 miles long?

No load? In theory, full voltage. The voltage drop is directly proportional to the current drawn.

Bruthal

I know, im just having a laugh, although a volt meter does have a load, just extremely small, especially a digital one.

2011

robbie7730 wrote: »

I know, im just having a laugh, although a volt meter does have a load, just extremely small, especially a digital one.

:D:D

RoundyMooney

robbie7730 wrote: »

No it seems a bit mad. Hard to believe the ESB connected that setup.

Why? The customer's installation is the responsibility of the customer. The installation was certified, and any follow up should be with the contractor who thought a 135 meter run from the interface was a good idea. I'd bet the distance from meter to transformer is probably half that or less.

Bruthal

RoundyMooney wrote: »

Why? The customer's installation is the responsibility of the customer. The installation was certified, and any follow up should be with the contractor who thought a 135 meter run from the interface was a good idea. I'd bet the distance from meter to transformer is probably half that or less.

Obviously its the contracor who should of looked after a proper installation alright. I thought there would be some limit to the length of tails myself though. Limitless so is it, once there is a cert?

2011

robbie7730 wrote: »

Limitless so is it, once there is a cert?

Pretty much, yes. The ESB are not really interested in anything beyond the meter. This was not the case in the past (pre ECSSA and RECI days). It is no longer their responsibility.

In fact I even know of a case (large commercial installation) where a RECI inspector informed the ESB that a new installation did not comply with the regs and the ESB refused to disconnect or get involved.

Bruthal

2011 wrote: »

Pretty much, yes. The ESB are not really interested in anything beyond the meter. .

No, but they have stated texting beyond the meter when the bill is overdue:eek:.

evosteo

robbie7730 wrote: »

I wouldnt think the 70 square would have to be terminated into the DB. It could be terminated into some sort of minipillar and then 16 square brought in the last few meters.

Realistically the meter should be moved to the house, as the meter is probably only supplied with 25 square as well.

i was thinking with me industrial helmet on.:D

jus sounds like a badly designed install.

longest run iv ever heard of anyway from a meter to a board

M cebee

robbie7730 wrote: »

No, but they have stated texting beyond the meter when the bill is overdue:eek:.

don't think there's any max length specified in rules

but the 4% installation voltage drop would include the tails

stick on an electric shower and you're dropping 10v on the tails alone here

i reckon the op may get by-depending on the loads

there should also be an mcb in cabinet at gate-if there isn't one

M cebee

to upgrade the tails you'd prob parallel another 3*25 with the existing tails

bringing the service to outdoor cabinet on house would be preferable though

paying the extra for 'enhanced' usually ensures good quality supply even though in theory you're entitled to it

2011

M cebee wrote: »

to upgrade the tails you'd prob parallel another 3*25 with the existing tails

I would not do this.

Power cables in parallel should be exactly the same lenght and type. It would be difficult to ensure that this is the case.

Also terminating two 3 x 25 sq. SWAs at both ends will be more hassel than it is worth!

Personally I would install the ducting and get the ESB to move the meter.

Bruthal

It sounds like it is already a 3x25 swa so it would be the same size and type.

M cebee

yes-can't see the problem at all

the exact length isn't an issue here as the tails would be protected at cabinet with '63amp main ocpd'

-they can be connected to 16's before the meter postion and DB in suitable boxes


i was only theorizing but if for arguments sake you decided to upgrade tails for VD-the cost difference between paralleling another 25 and fitting a new 50 is prob well over 1200 euro!!!

anyhow bringing the service to house is prob the way to go

Bruthal

There should be no problem with a couple of feet difference in length especially where the cables in parallel will not be loaded above what each cable on its own is rated at. Its only a volt drop problem. 25 square is not too small for the loading in the op`s case here, its only the length of run having too high a volt drop. The load wont be above the 63 amps or so, which each 25 Sq is capabable of carrying.

Paralleling 2 4x120 cables to have the current carrying capacity of a 4x240 would be the same length, mainly because they are obviously run the same way. But equal length helps ensure both share the load equally. In reality though, i doubt a couple of feet would make much difference here either, as the difference in impedence would be tiny.

M cebee

anyhow it's not the preferred option

i'd love to know why they thought this was good idea?

Bruthal

Im still surprised a meter can be put 135 meters from the dwelling. I know the supply company might say a cert was given to us etc, and they have nothing to do with anything beyond the meter, and thats fair enough, but i thought there would be some association made between a meter location and the metered dwelling in a domestic setup.

Overall it sounds like a cost cutting measure in terms of getting the supply brought to the house, but its even more surprising a contractor thought a 25Sq cable would do the job.

M cebee

in fairness to ESBN

the installation is the responsibility of the contractor

they have enough to be doing


hmm-now you got me thinking robbie

this would never be a temp supply at perimiter of site and new installation connected to it ??

nothing would surprise me

ft9

I'd love to know the reason or thinking behind why the meter was placed so far away?

2011

M cebee wrote: »

yes-can't see the problem at all

If cables are paralleled they must be exactly the same specification, insulation type, conductor type and size, length, routing, exposed to the same ambient temperature etc. Ideally even the manufacturer of the cable should be the same. That way the impedance of each cable is exactly the same, so the load is evenly split. If the load is not evenly split you could not treat two 3 x 25 sq. SWAs as though it were a 3 x 50 sq. SWA from a design point of view.

It is not good enough to say they are both 3 x 25 sq. SWAs.
For example, if one 3 x 25 SWA is XPLE and the SWA is PVC the XPLE (with all else being equal) the load will not be evenly distributed.

You can argue that it would still work (and you would probably be correct), but it would not be done correctly or in a professional manner (as far as I am concerned).
In my opinion when it comes to mains cabling it should be done 100% correctly or not at all.

I have been involved in paralleling power cables several times for transformers (6 x 630 sq. singles), generators, and more recently very large motors.
In all cases the design team went to a lot of trouble to ensure that all paralleled cabling was identical.

]the exact length isn't an issue here as the tails would be protected at cabinet with '63amp main ocpd'

I am not arguing that the cables would not be adequately protected, they would be. The reason for paralleling is the same reason for installing a larger cable i.e. to deal with the volt drop issue.

-they can be connected to 16's before the meter postion and DB in suitable boxes

They could, but it would not be something I would like to do. I never ever like to join mains cables.

i was only theorizing but if for arguments sake you decided to upgrade tails for VD-the cost difference between paralleling another 25 and fitting a new 50 is prob well over 1200 euro!!!

I know, point taken.

anyhow bringing the service to house is prob the way to go

Agreed.

Sometimes the only correct solution is a very expensive one!

Bruthal

Doughal maguire from the esb put the meter in. He thought the house was small, but it was actually far away.

Bruthal

2011 wrote: »

That way the impedance of each cable is exactly the same, so the load is evenly split. If the load is not evenly split you could not treat two 3 x 25 sq. SWAs as though it were a 3 x 50 sq. SWA from a design point of view.

This will be like the conduit arguement, but the 2 paralleled cables would not need the current carrying capacity of a 50 square, only the smaller volt drop, they are not the same thing precisely. The single cable is never going to be overloaded here, it just has too high a volt drop, so two in parallel will never have either cable carrying its rated capacity in the OP scenario here.

Also, there will be differences in impedences even of a 100 meter length of cable cut in half.

Two paralleled cables dont need to carry exactly half of the current each, but in practice they likely will be very close anyway. Also 2 smaller cables have a slightly higher capacity than a single big one anyway, so a slight variation in the split current is not a problem.