Isolator for motorised valves???

bobby brown

Hi all,I am new on here and have enjoyed reading through some of the posts in this section over the past couple of months.I am a self employed conscientious sparks and have been with reci since 93/94,but at the game since 1980.I dont usually have any problem with new regs etc,but this one has me stumped.I have spoken to a few guys in the trade and they have said "I dont wire them like that,so a fused spur will do....".The problem is how do you isolate a motorised valve if it is wired for an proper "S" plan control system with potentially 4 current carrying conductors at the valve.Most of the time these are a lot more than 2M from boiler,i.e in the hot press,Are you supposed to use a big 3P+N isolator,possibly 3/4 times the size of the motorised valve and totally over rated for purpose?See below 4th from the end.Had thought about an extractor fan isolator,but only 3 poles and cannot find anything with 4 poles anywhere.Suggestions please.
Cheers,bobby.
Top 10 breaches of the ET101 National Rules for Electrical Installations

22.11.2011



Listed below are the 10 most common breaches found as a result of audit & inspections carried out by our inspectors under the Common Performance Evaluation Scheme (CPES) since the start of the year.

Please ensure you are aware of and comply with these rules as the inspectors will be keeping a watchfull eye for these breaches.
Rule No 701.416
Description: 1 Dedicated RCD required for bathroom circuits
Rule No 530.5.3
Description: Distribution board at incorrect height
Rule No 531.2.2.2
Desciption: RCD test notice required at distribution board
Rule No 533.3.5
Description: Main protective device required at meter cabinet
Rule No 544.2.8
Description: Metal sink(s) not bonded
Rule No 530.5.12
Description: Distribution board not labelled
Rule No 555.1.2
Description: Local isolation required for motorised valves, oil burner, heating system, circulation pump, etc
Rule No 554.3.5
Description: Isolation required for all inaccessible sockets
Rule No 555.3.2
Description: No RCD on heating system
Rule No 514.3.1
Description: Incorrect colour code for cable wires

M cebee

i usually bring the heating supply into a DP switched spur adjacent to valves or wiring centre and fit an additional isolator for boiler

2011

M cebee wrote: »

i usually bring the heating supply into a DP switched spur adjacent to valves or wiring centre and fit an additional isolator for boiler

Exactly what I was going to say. That will isolate all 4 cores going to each zone valve.

2011

Listed below are the 10 most common breaches found as a result of audit & inspections carried out by our inspectors under the Common Performance Evaluation Scheme (CPES) since the start of the year.

Please ensure you are aware of and comply with these rules as the inspectors will be keeping a watchfull eye for these breaches.
Rule No 701.416
Description: 1 Dedicated RCD required for bathroom circuits
Rule No 530.5.3
Description: Distribution board at incorrect height
Rule No 531.2.2.2
Desciption: RCD test notice required at distribution board
Rule No 533.3.5
Description: Main protective device required at meter cabinet
Rule No 544.2.8
Description: Metal sink(s) not bonded
Rule No 530.5.12
Description: Distribution board not labelled
Rule No 555.1.2
Description: Local isolation required for motorised valves, oil burner, heating system, circulation pump, etc
Rule No 554.3.5
Description: Isolation required for all inaccessible sockets
Rule No 555.3.2
Description: No RCD on heating system
Rule No 514.3.1
Description: Incorrect colour code for cable wires

Very interesting, thanks

meercat

interesting question bobby brown
i see your dilemma here
if you have 2 motorized valves in the hot press ,how do you isolate them
assuming both have live, neutral and earth plus auxiliary contacts(meaning 3 pole isolation for each)

M cebee wrote: »

i usually bring the heating supply into a DP switched spur adjacent to valves or wiring centre and fit an additional isolator for boiler

will the isolator for the boiler then have to be 3 pole(permanent live, neutral ,earth and switched live)?
how is this achieved?

im not doubting you or questioning your ability here,i just cant see a simple solution off hand and would like to be prepared in case i come across this arrangement
thanks

mattjack

meercat wrote: »

interesting question bobby brown
i see your dilemma here
if you have 2 motorized valves in the hot press ,how do you isolate them
assuming both have live, neutral and earth plus auxiliary contacts(meaning 3 pole isolation for each)




will the isolator for the boiler then have to be 3 pole(permanent live, neutral ,earth and switched live)?
how is this achieved?

im not doubting you or questioning your ability here,i just cant see a simple solution off hand and would like to be prepared in case i come across this arrangement
thanks

S plan has two motorised valves , does that mean you need two 3p N isolators ? I,m away from domestic awhile now..are isolators outside hot press ?

M cebee

meercat wrote: »

interesting question bobby brown
i see your dilemma here
if you have 2 motorized valves in the hot press ,how do you isolate them
assuming both have live, neutral and earth plus auxiliary contacts(meaning 3 pole isolation for each)

M cebee wrote: »

i usually bring the heating supply into a DP switched spur adjacent to valves or wiring centre and fit an additional isolator for boiler

will the isolator for the boiler then have to be 3 pole(permanent live, neutral ,earth and switched live)?
how is this achieved?

im not doubting you or questioning your ability here,i just cant see a simple solution off hand and would like to be prepared in case i come across this arrangement
thanks

It is simple
I normally use a 3 pole isolator for boilers
Each mv wont need to be individually isolated if they're in same location

meercat

thanks m cebee

mind if i pick your brains

in an installation with hotpress and 3 zones(hot water,upstairs central heating,downstairs central heating)
2 mini valves in hotpress ,1 minivalve beside boiler downstairs

would you wire power to switched fuse in hotpress
then feed time clock downstairs and then send power back upstairs to feed mini valves and then send auxiliary contacts back downstairs to switch boiler on

this is without thermostats or isolators for the minute

M cebee

an additional isolator for mv beside boiler id say
3 in total
1 switched spur,2 isolators
for a boiler that takes perm feed and switched live

meercat

thanks m cebee
what type of isolator would you recommend for the mv beside the boiler
(assuming i would need to isolate the auxiliary contacts also)

M cebee

4Pole

Bruthal

I would of thought that if you have the boiler, timeclock, and MV`s all in the one location, a 2 pole isolator will do for the lot.

bobby brown

M cebee wrote: »

i usually bring the heating supply into a DP switched spur adjacent to valves or wiring centre and fit an additional isolator for boiler

Thanks mate,excellent idea, and probably the answer to most of these kind of situations.The problem I have is that the U/F heating manifold (wiring centre) and about 20 mini motorised valves controlled by stats (large 3 storey house) is 8m from the boiler,and there are a couple of motorised valves to deal with in the hotpress upstairs for hot water and rads on top floor.Thanks for all replys lads.Cheers,bobby

2011

robbie7730 wrote: »

I would of thought that if you have the boiler, timeclock, and MV`s all in the one location, a 2 pole isolator will do for the lot.

Would agree, one it is clearly labelled.