Measuring my diversion

Hi hope someone can help

I have a 'Robins MkII' diverter that has been running brilliantly for about two years now with no problems . . . . until now.

I have been measuring my diversion via a plug-in monitor that I purchased from Maplin, that measures all the things you would want to - I find it useful to use the 'amps' setting as it gives me a great way of checking that all is right with the system.

Until November 2014, I was running a 1kW immersion heater that I had installed before purchasing the Robin, with a view to some other form of Diverter - then I was persuaded to go the Robin route.

In November I had a change of cylinder which came with a 3kW immersion.  All was well until the other day the neutral in the plug top burnt out!!  I have rewired it, but I feel the system is unsafe.  Research points to the fact that 13A plugs do not like being run at 12.5 amps for any length of time, and on a sunny day, that is what is happening. Of course with the 1kW immersion the max current was way less, about 4A.

My question is:- how can I measure what I want to do safely ? I cannot find a hard-wired meter that will give me what the plug-in one does, accumulated kWh and amps on the same unit. I have looked at a digital meter for the kWh, but would have to use a ammeter (somehow) for the system check.

Any ideas would be gratefully received.

Thanks in anticipation.


Robert Wall's picture

Re: Measuring my diversion

Without knowing exactly how or why the plug burned out - was it a loose screw, or lack of contact pressure in the socket - I'd suggest that you replace both plug and socket with ones from a reputable maker, Crabtree for preference (and no, I don't get commission!). A BS 1363 plug should be good to 13 A indefinitely, if it's in good condition.

It shouldn't be running 13 A continuously - unless you're using the hot water as fast as it's being generated, because the tank thermostat should operate and prevent boiling.

Alternatively, you could hard-wire the immersion heater into a fused spur outlet, but you'd lose the ability to have a plug-in monitor.

If you need a visual check, why not try to pick up a second-hand mechanical (Ferraris) kWh meter, preferably without a ratchet, so that you can see the disc see-sawing? (The pre-payment type could have the coin mechanism disabled, and could be got quite cheaply when I last looked.)

[N.B. NEVER 'tin' the wires that are going into a screw terminal (and if they are tinned, cut the tinned part off), because that is a sure way to lose contact pressure over time as the solder flows and arcing and burning is sure to follow.]

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