can any sparkies advise ?

anotherbaldrick

Our neighbour who moved into her new build 6 months age has found out that the reason her immersion heater has never worked is because no fuse was fitted in the switched spur. My question is can the circuit be tested and passed sound if there is no fuse fitted ? Would it not have shown up on the equipment as "open circuit".

diable

She should contact the company she bought the house from to check it over.

macman

Possibly a fuse went somewhere else after testing and sign off and was 'borrowed' and never replaced. Stranger things have happened.
It took 6m to notice that there was no hot water?

muckybutt

anotherbaldrick wrote: »

Our neighbour who moved into her new build 6 months age has found out that the reason her immersion heater has never worked is because no fuse was fitted in the switched spur. My question is can the circuit be tested and passed sound if there is no fuse fitted ? Would it not have shown up on the equipment as "open circuit".

Testing only covers the fixed wiring ie upto the double pole switch on the fcu, the fuse is after the switch so would therefore have not been tested. If the switch with fuse in and turned on during testing, this would have shown as a fault.

Hope that clarifies that for you.

vaio

I initially was thinking the same but wouldn't a permanent connection at the spur count as fixed so the loop test should be done at the terminals of the heater?

when we do testing we go to the furthest point we can so a permanently wired submersible pump on flex (sealed so no access to pump end connections) gets an R2 reading taken or a plug in machine gets a loop reading done at the furthest motor

Either way I'm staggered the snagging man didn't pick it up or do they leave snagging to the buyer these days?

muckybutt

vaio wrote: »

I initially was thinking the same but wouldn't a permanent connection at the spur count as fixed so the loop test should be done at the terminals of the heater?

when we do testing we go to the furthest point we can so a permanently wired submersible pump on flex (sealed so no access to pump end connections) gets an R2 reading taken or a plug in machine gets a loop reading done at the furthest motor

No ! if you were to test at the heater terminals then you would be testing through the element for starters, you would also be testing the flex which is not part of the fixed wiring, bit like a cooker point and connector below, you would only test as far as the cooker connection point / outlet, any further than that and you would then be testing through the appliance.

vaio

Don't understand what you mean about the element, it wouldn't have any effect on a loop test.

Surely if you don't do the loop test at the furthest point than how can you be confident that the protective device will disconnect in the event of a fault?

Maybe the extra impedance of a couple of feet of flex between spur and heater is bug ger all, but if you have 20m of flex between connection point and a pump or motor then surely you need to test as we do because the impedance of that flex could be significant

muckybutt

vaio wrote: »

Don't understand what you mean about the element, it wouldn't have any effect on a loop test.

Surely if you don't do the loop test at the furthest point than how can you be confident that the protective device will disconnect in the event of a fault?

Maybe the extra impedance of a couple of feet of flex between spur and heater is bug ger all, but if you have 20m of flex between connection point and a pump or motor then surely you need to test as we do because the impedance of that flex could be significant

Loop tests are only done on the fixed wiring as well, the flex to the element isnt part of the fixed wiring, same would go for all the fixed wiring tests required. Testing the flex from point of connection on fixed wiring is not part of testing.
If its got a flex on it then its a pat test that would be required if its portable.
So immersion flexes - towel rads - cooker ingnitions - fans - pond pumps etc are not fixed wiring therefore should not be tested as you are doing. If you are testing the flex then you are testing wrong which alters all your readings.
Yes you test at the furthest point, the point being the last fixed connection point on the wiring, not at the appliance nor the flex.

southcoastrgi

another question for you two, i have always been led to believe that a 3kw immersion heater shouldn't be connected to a switched fused spur as if the supply was 230v this would take it over the max 13a fuse rating ?

vaio

southcoastrgi wrote: »

another question for you two, i have always been led to believe that a 3kw immersion heater shouldn't be connected to a switched fused spur as if the supply was 230v this would take it over the max 13a fuse rating ?

amps = power/volts = 3000/230 = 13A

so just on the limit but if you look at the fuse curve you'll see that a 13A fuse will carry 20A pretty much indefinitely so not likely to be a problem in reality.

in fact if you look at the curves for mcb's & fuses you'll often find that under fault conditions the upstream B16 or even B32 mcb will open before the 13A fuse melts, all depends on the fault current

vaio

muckybutt wrote: »

Loop tests are only done on the fixed wiring as well, the flex to the element isnt part of the fixed wiring, same would go for all the fixed wiring tests required. Testing the flex from point of connection on fixed wiring is not part of testing.
If its got a flex on it then its a pat test that would be required if its portable.
So immersion flexes - towel rads - cooker ingnitions - fans - pond pumps etc are not fixed wiring therefore should not be tested as you are doing. If you are testing the flex then you are testing wrong which alters all your readings.
Yes you test at the furthest point, the point being the last fixed connection point on the wiring, not at the appliance nor the flex.

Flex can be part of fixed wiring but in any event if you understand why loop tests are done then I'm sure if you think about it you will realise why the test needs to be done at the furthest point to ensure the safety of your customers whether that is spur/flex or appliance.

On immersion heaters, apart from anything else you need to pop the top off the element connection point anyway and it's much easier to to clip test leads onto the posts in there than it is faffing about in the back of a spur