110 volt 16 amp sockets on a 32 amp ring

[Flanders]

When caring out an EICR on a site I found that the 110 volt socket outlets were connected as three 2.5mm ring final circuits each protected by a 32 amp MCB (single Pole) in a DB fed from 110 volt transformer ,These sockets are used to supply halogen Flood lights that area plugged in when required ,there is about 10 on each circuits

Now I know this is not the correct way of doing it ,as I would of installed radial circuits protected via 16 amp double pole MCBs

There for due to the possible over load of the 16 amp sockets and the fact that there is no over current protection on the return leg I gave this observation a code 2

Am I being over the top as this installation has been in use for a least 10 years and is showing no signs of thermal effects

As thinking about it ,the lights that are being used will not overload the sockets and the 2.5mm ring can not be overloaded as the 32amp mcb would trip out ,

Only problem is any other appliance could be plugged into the 110 volts sockets so this was also my thinking for the code 2 observation

 

[Pete999]

Think about it, you say you have 110v sockets connected to a 230v supply, what would be the implications of someone plugged a 110v appliance into the socket? BOOM comes to mind

 

[Octopus]

C2 imho

 

[kyle12111994]

Think about it, you say you have 110v sockets connected to a 230v supply, what would be the implications of someone plugged a 110v appliance into the socket? BOOM comes to mind

He never said the 110V sockets were on a 230V supply, they are fed from a 230V - 110V transformer via 32A MCB's. What he is saying is, anybody can come along and unplug the lights to plug in other pieces of equipment, which could draw more current than the lights.

 

[Pete999]

He never said the 110V sockets were on a 230V supply, they are fed from a 230V - 110V transformer via 32A MCB's. What he is saying is, anybody can come along and unplug the lights to plug in other pieces of equipment, which could draw more current than the lights.

So he did must read the posts properly, my mistake

 

[Darkwood]

The same regs that define standard ring and radials at 230v also apply to 110v systems and quite rightly where you point out the lack of O/L protection due to the nature of 110v plugs not having integral fusing then you need to code accordingly as you would any other circuit with no sufficient O/L protection.

If the install is indeed 10yrs old then its more luck than judgment that has seen no issues, it was required back then and is required now to have O/L protection to ensure the outlets cannot be overloaded with loop-in lighting or multiway outlets.

 

[Flanders]

C2 imho

thanks i thought so it was another electrian who mentioned that you could use a ring but i would never do it this way .its the single pole mcbs that made me go for a code 2 if they were double pole i may have given a code 3 due to the way the installationis used

 

[Flanders]

The same regs that define standard ring and radials at 230v also apply to 110v systems and quite rightly where you point out the lack of O/L protection due to the nature of 110v plugs not having integral fusing then you need to code accordingly as you would any other circuit with no sufficient O/L protection.

If the install is indeed 10yrs old then its more luck than judgment that has seen no issues, it was required back then and is required now to have O/L protection to ensure the outlets cannot be overloaded with loop-in lighting or multiway outlets.

yes i agree i will recomend to change the db and fit 16 amp double pole mcbs tne current db is site made ,to be fair i dont know why a 240 volt circuit wasnt installed as these are just fixed halogen lamp that shine into the back of lorrys on loading bays .

 

[Darkwood]

yes i agree i will recomend to change the db and fit 16 amp double pole mcbs tne current db is site made ,to be fair i dont know why a 240 volt circuit wasnt installed as these are just fixed halogen lamp that shine into the back of lorrys on loading bays .

Some sites require 110v when leads are trailing across floors and won't allow 230v.

 

[Flanders]

Yes but this set up just has an 110 volt socket at the loading bay door with a 110 volt halogen lamp fiited to the wall on a braket so ths light can swing into tne back of the trailer the flex from the light is the correct length to fit into the socket and so not trailing any ware , all oyhet sites i have been on have a 240volt set up

 

[Flanders]

Yes but this set up just has an 110 volt socket at the loading bay door with a 110 volt halogen lamp fiited to the wall on a braket so ths light can swing into tne back of the trailer the flex from the light is the correct length to fit into the socket and so not trailing any ware , all oyhet sites i have been on have a 240volt set up

 

[benji]

The 110v transformer is it 110v-0v or 55v-55v ct

 

[Flanders]

Its 55v -55v

 

[Deleted member 9648]

Its 55v -55v

If it's a centre tapped transformer 55-55v then the mcb's must be double pole,that is a separate coding issue from the lack of O/L protection. Code 2 for the O/L issue and code 2 for S/P mcb's.

 

[Flanders]

Yes sorry to clarify I have coded them separately as code 2 observations , all i was saying was that if they had been double pole 32 amp mcbs and the installation was to a good standard which it wasn't I would off been edging to a code 3 observations due to the use of the installation and no signs of thermal damage , its just the part were there is no OL protection for the individual lights but is this required ?

Can an 500 watt halogen light course an over load for example when the lamp blows and pull more than 16 amps and so possibly coursing damage to the 16 amp socket or to the 1.5mm flex supplying the light . I don't think it would and not sure of the maths if any to work this out

 

[Lucien Nunes]

A lamp is unlikely to cause an overload as it will tend to blow very quickly if much of the filament is shorted out, so in one sense it's a fixed load. But certain types of lamp, especially small powerful halogens, can flash over inside the bulb as the filament breaks and draws an arc. To control the damage the lamp maker will specify a maximum fuse or MCB rating and curve, to limit the let-through in the event of violent lamp failure.

I have been standing next to a Par 64 that had a lamp flashover when protected only by a B32 and it was like a cannon being fired - A singing arc for about 1/2 second followed by a huge flash and bang and broken glass and quartz shot out of the front all over the room. A linear is unlikely to do this because the terminals are so far apart but still I would respect the manufacturers' fuse specs.

 

[UKMeterman]

Hi,
I have seen linears explode as well, very nasty as they were being used for indoor down lighters in a church. There was no intervening glass shield. When they fail the arc causes the pressure pulse causes the quartz tube to burst.

In this particular case it may be the impedance of the 230-110 transformer that has limited the fault current of any arcs that they have had. I would also suggest getting the MFT out and check the prospective fault current is acceptable for a 32A circuit breaker.

 

[Flanders]

The only test of done so far is ring continuify on the live 1.74 , neutral return 1.77 and earth 1.70 , IR of 128 live to live and 127 live to earth , i have not done any live test yet not sure if my mft will test at 110 volts i will have to check , i am going back to the site in a couple of weeks so will do some more investigation then. As these reading are high i think this is another reason to down rate the mcb to 16 amp