Help with wiring a MAIN unvented 170 direct cylinder

[JACKC]

"You will need two B16 circuits off the consumer unit, wired in minimum of 2.5.sq.mm cable, to a pair of 13amp DP switched fuse-connection units in the cylinder cupboard, and then 1.5.sq.mm immersion flex from each FCU to each element. "
Sorry but water heaing elements over a certain litreage (can't remember figure of the top of my head but 15 ltrs sounds familiar) must be supplied by a 20 apm double pole switch and not a SFCU.

 

[RF Lighting]

I'm not aware of any regulation which calls for this.

Can you tell us which regulation states this?

 

[scottyboyiow]

Not heard of that before either JackC, could you lead me to that reg? Thankyou Kai for your input, this was the road that I was looking at going. For anyone else that comes to read this post, after again speaking to the MAIN technical helpline, I was informed that the two seperate feeds too two seperate FCU's was the best way. I asked if there was any other controllers needed, with regards to the ELECTRICAL side and was informed the only other controller would have been if it was being used for the ECO 7 tariff. So I am still intrigued as to what other control was needed as stated by Taylortwocities and Bernard Green?

Flameport - The heating is done via these http://www.economy-radiators.com/index.html?gclid=CPDGk5WzkK4CFQlpfAodlRmJhw

Thats one of the reasons there is no longer an ECO tariff. Still waiting to see whether they are as good as stated, but only time will tell! Anybody had any dealing with these that could tell whether they really are as good as stated? Abit dubious that they are as cheap to run as CH, as electricity is more expensive thn gas per kWh.

 

[scottyboyiow]

I should proberly add that each element has a built in thermal cut out aswel as a thermostat.

 

[scottyboyiow]

Nothing from taylortwocities and Bernard green? I guess I didn't really expect an actual answer!

 

[bernardgreen]

I gave you my advice. Have it installed by a qualified person who knows the regulations that are applicable and the dangers and how to ensure as far as is possible the system is safe. The danger of explosion and the necesary safety systems are not part of Building Regs Part P or the electrical wiring regulation but are controlled by ( I think ) Part L of the building regs.

It isn't only boiling water that can blow an un-vented cylinder. Although unlikely if RCD protection has been fitted a leaky element causing a live to earth current through the water will electrolise the water into hydrogen and oxygen in exactly the right mixture for an explosive burn inside the tank.

One ignition source is when the hot tap is turned on by someone smoking, after the water in the pipe comes the highly explosive mixture that will burn back along the pipe and into the tank.

 

[scottyboyiow]

Just for anyone who comes across this post for info. The two elements were fed from two seperate B16 MCBS, which were also protected by 30mA Rcds. Feeds into two FCU's and each element fed from these. Dont know about other tanks, but the tank in question, all protective devices with regards to over pressure are mechanical and part of the plumbers installation. After more research I could still find no other information about 'electrical interlocks' and see that taylortwocities has gone quiet on this matter. The plumber commissioned the tank and sent away for the certificate for the tank.

 

[matt1e]

Just for anyone who comes across this post for info. The two elements were fed from two seperate B16 MCBS, which were also protected by 30mA Rcds. Feeds into two FCU's and each element fed from these. Dont know about other tanks, but the tank in question, all protective devices with regards to over pressure are mechanical and part of the plumbers installation. After more research I could still find no other information about 'electrical interlocks' and see that taylortwocities has gone quiet on this matter. The plumber commissioned the tank and sent away for the certificate for the tank.

The only other electrical safety interlocks required apply to indirect cylinders (overheat stat req to close off the source of heat to the coils) as yours is a direct one then they don't apply
your G3 installer will hopefully have installed the machanical ones

Matt